Animal fighter tier list

[Infinity Blade]

To be fair, that Tarbosaurus should have a significantly wider snout than Hurum & Sabath depict (Greg Paul pointed this out in The Tyrant King, I’ll try to dig up the info again if anyone wants), but I believe it indeed did not have as wide of a skull in the posterior end.

Not to say I think it was significantly inferior to T. rex in fighting ability (ofc not saying anyone here suggested so either).

[lionclaws]

Sept 24, 2023 16:54:33 GMT 5 theropod said:

Sept 24, 2023 8:12:04 GMT 5 lionclaws said:

There's more to a fight than weaponry, IMO.

In Game of Thrones, Jon Stark tells Arya Stark that the way to win a sword fight is to "stick 'em with the pointy end." Anyone who knows anything about sword fighting knows that's nonsense. The key to winning a sword fight is to not get stuck.

So ability to cause debilitating injuries is only half of the battle, and arguably the smaller half. The ability to avoid being injured is by far the greater half.

There are several ways to do this. The most obvious is by being too big to be easily injured, but let's limit ourselves to methods that work at similar weights.

Aggression is arguably the best method to make up for a weaponry disadvantage. All things being equal, whoever delivers a serious injury first is liable to win. Even if that injury isn't fatal, the victim's performance for the remainder of the fight will be degraded. While my "unique" contributions to the Lion vs Tiger debate were primarily biomechanical, I have always viewed aggression as the critical difference between the two animals, and the one that gives the Lion the edge.

Grappling ability is also a viable tactic. This is what makes saber-tooth cats (and, arguably, dromaeosaurs) such dangerous animals in a fight - not only do they have formidable weaponry, they are capable of controlling their opponent's weaponry to some degree in most fights.

Agility is another good way to avoid injury. Being able to control the distance in the fight, so that you are consistently able to bring your weaponry to bear while denying your opponent the same? That's dangerous. This, combined with the strong evidence of face biting in most theropod taxa, is one of the reasons I tend to back tyrannosaurs against carnosaurs at equal masses. Yeah, the carnosaur has better weaponry. But what does that matter if the tyranosaur always in a better position due to constant maneuvering?

Durability is another extremely relevant factor, for reasons that should be obvious. The best sword in the world won't cut through plate harness, so even if the guy in armor has a rusty kitchen knife, he's liable to win against a better armed but unarmored opponent. This is what makes mustelids in general such good fighters.

In general, compactness/robusticity of build has a big impact on all of the above - putting the same amount of muscle on shorter limbs with a broader chest will consistently improve both flexibility and strength - and thus grappling ability - while simultaneously lowering rotational inertia and increasing durability. Bears take advantage of this, and are, imo, some of the best fighters in their weight class despite having lackluster weaponry.

In general, for terrestrial fighters, I see bears, mustelids, dromaeosaurs, and sabertooth cats as being S-tier fighters, with the "Cookie-Cutter-Cat" standing out as having the best balance of adaptations - compact, good grappling ability, and a theropod-like "exanguinate anywhere" bite. I'm not aware of any animal with a comparable suite of adaptations.

Lions get honorable mention just for being gangster murder hobos, but they're ultimately A-tier, same as most pantherine cats, as well the tyrannosaurs and abelisaurs (both of which I place on the lower end of A-tier).

The giant carnosaurs were at the peak of B-tier, with most other theropods (in my opinion) spread throughout the B and C tiers. Wolves are middling C-tier, while hyenas (due to sheer durability) are peak C-tier.

Spinosaurs generally, and Spinosaurus aegypticus specifically, were F-tier. They were hyperadapted for killing small prey to the exclusion of animals in their own size range.

There is one important aspect I think is missing in this list, especially since we are already speaking in terms of analogy with human combat:

One of the most crucial advantages in any fight is reach and nimbleness in the attack. This is why in unarmoured fighting, a rapier will have an advantage over most other swords, and a spear (or similar polearm) will have the advantage over almost any other melee weapon (and of course a projectile weapon will have the advantage over pretty much anything anyway). These weapons will outrange and outmaneuver shorter, beefier weapons, and will generally have a distinct advantage over those other weapons as long as they are still capable of inflicting sufficient damage (which, in unarmoured combat, they generally are), which makes this probably the best way to simultaneously not get stuck with a pointy end oneself, and stick one’s opponent, because the opponent physically cannot get in range of their own weapons without first getting in range of yours.

The only thing that can really meaningfully negate this advantage is armour, which allows an opponent to potentially tank hits from such a weapon and bring one’s own (ideally more damaging, or more geared towards armour penetration at any rate) weapon to bear, but there is no real animal equivalent of steel plate, and the things that come closest (like crocodile/armadillo/turtle/placodont/ankylosaur armour) tend to incur such severe drawbacks in terms of mobility, that truly effective armour in the animal kingdom is mostly restricted to slow-moving animals (i.e. not available to the fast-moving terrestrial macropredators you are comparing here). There are of course more durable animals and less durable animals, but assuming similar overall sizes, few have the kind of durability that could really nullify the advantage of greater reach and striking speed.
I think that people generally tend to agree with this point based on  how highly rated animals with long, forward-facing horns like Triceratops tend to be in the context of a face to face engagement.

It is true that this is strictly speaking an aspect of the weaponery, but so is grappling ability (tied to claws or jaws), and, just like grappling ability, this is not directly related to the ability and potency of the weaponery to inflict injuries, so I think it belongs on this list for completeness’ sake.

The counterargument I'd make against the idea of "dimensional advantage" is that a) it's not particularly analogous to human weaponry, as the weaponry of an animal is part of it, whereas a weapon is a semi-disposable tool that we can afford to be damaged, and b) it doesn't hold up in real life examples. In general, a lankier, less heavily built animal will lose to one with a more compact bauplan, all things being equal.

Also some other things worth considering:
1) Since you are considering them all in their respective size-class: where would you place non-giant allosauroids (or giant carnosaurs that had non-reduced forelimbs, like Allosaurus/Saurophaganax)? This aspect completely changes the game in terms of your point about grappling: you have an animal that still has all the reach and striking speed advantages outlined above (that generally incur drawbacks when it comes to grappling ability with the jaws), but supplements those with a pair of massive forelimbs bearing 30 cm long meathooks, whose sole mechanical specialization is puncturing and clutching prey.

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The reason I don't take theropod forelimbs that seriously in near-parity fights with other theropods is pretty simple: lack of anterior range of motion.

Jan 17, 2015 22:38:29 GMT 5 theropod said:

Anteroposterior ranges of motion of some theropods (interim result):
Acrocanthosaurus redrawn from figures and measurements in Currie & Carpenter 2000, movement range from Senter & Robins 2005.
Allosaurus drawn as a composite from figures and proportions in Gilmore 1920 and Madsen 1976, movement range from Carpenter 2002.
Herrerasaurus based on figures, measurements and movement ranges in Sereno 1993.

All drawn to same humeral lenght.

Note the peculiar development: from a basal theropod, over an allosaurid, to a carcharodontosaurid, we see the range of motion, especially in the elbow, but also the shoulder, first decreasing, then increasing again. On the other hand, there’s a clear (and logical) trend towards proportionately shorter and stouter forelimbs, larger scapulocoracoids and proportionately shorter (but more massive) distal elements, with reduction in the third digit and increasingly massive built in the other two.
I plan on adding some more (that’s why it’s A, D, E for now), tough unfortunately there’s no information on movement ranges in all of them. It will be interesting to see this directly compared to abelisaurs, tyrannosaur and deinonychosaurs.

References:
Carpenter, Kenneth: Forelimb Biomechanics of Nonavian Theropod Dinosaurs in Predation. Senckenbergiana lethaea, Vol. 82 (2002); 1; pp. 59-76
Currie, Philip J.; Carpenter, Kenneth: A new specimen of Acrocanthosaurus atokensis (Theropoda, Dinosauria) from the Lower Cretaceous Antlers Formation (Lower Cretaceous, Aptian) of Oklahoma, USA. Geodiversitas, Vol. 22 (2000); 2; pp. 207-246
Gilmore, Charles W.: Osteology of the carnivorous Dinosauria in the United States National Museum, with special Reference ro the genera Antrodemus (Allosaurus) and Ceratosaurus. Smithsonian Institution United States National Museum Bulletin, Vol 110 (1920); pp. 1-159
Madsen, James H.: Allosaurus fragilis: a revised Osteology. Salt Lake City (1976)
Senter, Phil; Robins, James H.: Range of motion in the forelimb of the theropod dinosaur Acrocanthosaurus atokensis, and implications for predatory behaviour. Journal of the Zoological Society of London, Vol. 266 (2005); pp. 307-318
Sereno, Paul C.: The Pectoral girdle and Forelimb of the basal Theropod Herrerasaurus ischigualastensis. Journal of Vertebrate Paleontology, Vol. 13 (1993); 4; pp. 425-450

Also, Brown et al 2021 documented face-biting in a wide range of theropods. Since most large (>1.5 tonne) theropods are only really worth comparing to either large mammals/herbivorous dinosaurs or other theropods, this has significant implications for how theropod matchups would go.

2) What about flight? There’s literally no animal on the planet that seems to have more favourable matchups against other carnivores in a similar weight class than the golden eagle (which I also don’t see in your ranking), and the key advantage here is that flight gives raptors the power to completely dictate the terms of almost any engagement. They are formidable on the ground, but with this stacking the odds in their favour, they take out and even prey on mammalian carnivores larger than themselves somewhat regularly.

I think that Haast's Eagle is probably the 15 kg equivalent to what the Cookie-Cutter Cat is for the 200+ kg weight class. Eagles are definitely terrifying, and I didn't include them in the list because (as you point out) they kinda have hacks.

3) In terms of tyrannosaurs, it’s important to differentiate which ones we are talking about. People usually generalize from T. rex (typically touted as "superior" to "normal theropods" in all ways imaginable) to other tyrannosaurids or even all tyrannosauroids. But the vast majority of all tyrannosauroids were <3m mesopredators, and even among tyrannosaurids, which do show many novel specializations (chiefly for mobility) and are generally large, apex predators, almost all of them seem to perform very similarly to same-sized carnosaurs in terms of tooth and skull strength metrics (see the Snively et al. 2006 study I cited on the other thread). So really, whether one agrees with their basic point, usually when people say "tyrannosaurs", what they really mean is Tyrannosaurus rex, which is a major overgeneralization of the many tyrannosaurids that were quite different from T. rex in terms of their feeding apparata.

I would point out that the other tyrannosaurs seem to still have fairly strong neck muscles and higher than average bite forces. Rex's overengineered skull seems to be designed to allow a level of inertial feeding that other, more slender-toothed relatives just didn't require.

We can debate as to why this level of inertial feeding was necessary for Rex specifically, but (in general) there seems to have been a tradeoff between weaponry and strength that likely didn't have too much of an effect on overall combat performance. Other tyrannosaurs were still robust and agile, they just had better weaponry as a result of their carnosaur-like skulls.

[Supercommunist]

Sept 24, 2023 15:04:45 GMT 5 Infinity Blade said:

Sept 24, 2023 8:59:06 GMT 5 Supercommunist said:

Grappling is obviously a powerful assest amongst more modest size but wrestlers are not always able to prevent non grappling animals from biting them in self defense.


Hyenas for instance, often manage to bite lions in self defense even when they are put in a headlock.

Interesting. I always thought that big headed predators (eg. many theropods, hyaenodonts, entelodonts, etc.) could prevent getting grappled in the first place with their huge jaws, but I didn’t realize even a hyena could do so against a much larger lion. Similarly, I’ve seen a video where a zebra gets its neck restrained by a lioness, but the zebra was able to nip her flank with its front teeth. It ultimately escaped.

m.youtube.com/watch?v=kXwG-ms63X8

Also, in that cougar-wolf fight that happened in B.C. several years ago, the wolf ultimately lost, but initially both animals were said to have had a grip on each other in their jaws. It was only after the wolf was startled by the observer that it let go of the cougar and tried to flee, allowing the cougar to counterattack and kill the wolf.

He says the wolf had the advantage early in the fight, when each animal had the other locked in its jaws. He admits he may have influenced the fight when he made a move that startled the wolf, causing it to flee. "Then the wolf decided to let go and the cougar made one leap and nailed the wolf," Mizak said.

www.ctvnews.ca/mobile/canada/cougar-vs-wolf-unreal-battle-caught-on-video-in-b-c-1.2411625

Obviously not saying grappling isn’t useful, it certainly is, but lots of people on CF used to act as if a non-grappling predator caught by a grappler was automatically screwed. That doesn’t appear to be completely true.

Preventing a bite during a frontal engagements seems to be difficult in general.

Coyote bites cougar.

www.youtube.com/watch?v=uKpL8213WE4&ab_channel=barryk.

Otter bites lioness.

www.youtube.com/watch?v=yFV4SbZv10s&ab_channel=EarthTouch

Dog bites leopard.

Jaguars in general seem wary when attacking peccaries from the front.

www.youtube.com/watch?v=a0KWhLUSC4Y&ab_channel=WBPSHORTS

www.youtube.com/watch?v=ZWExP3KJmRY&ab_channel=SeanKeuroghlian-Eaton

Grappling obviously is very useful against most animals but modern predators mainly prey on animals that use their horns or kicks to defend themselves. If you grab a bull by the head it can't really fight back until it shakes you of since it relies on momentum to deal damage. In constrast,an animal's jaw power isn't diminished just because someone is grabbing you. Sure, it might prevent them from shaking their head or something but the teeth are going to dig in and bites are a lot easier to land in general.

[theropod]

Are there actually published bite force estimates for non T. rex tyrannosauroids? There might be, but the last time I had a truly comprehensive overview of the theropod literature (back when I made that comparison posted above) that wasn’t the case. If they are higher than the average theropod, then at least it is doubtful if they are higher to such a high degree as to make a truly significant difference for grappling with something (esp. since the teeth and skulls aren’t actually stronger).

they kinda have hacks

Well yes, but that could basically be said for anything that gives one animal an advantage over another animal in some way.

The counterargument I'd make against the idea of "dimensional advantage" is that a) it's not particularly analogous to human weaponry, as the weaponry of an animal is part of it, whereas a weapon is a semi-disposable tool that we can afford to be damaged, and b) it doesn't hold up in real life examples. In general, a lankier, less heavily built animal will lose to one with a more compact bauplan, all things being equal.

Are there any actual real life examples where the condition "all else being equal" is met though? An example that comes up often, to the point of being quite annoying is leopard vs cheetah, but this is not a good analogy for the kind of differences I outined; a cheetah has a shorter skull than a leopard, not a longer one, and it also has semi-retractable claws and inferior limb dexterity, putting it at a grappling disadvantage due to more than simple robusticity or lack thereof, all that while not having any weaponery that would make it less reliant on grappling (quite the contrary). These are not features that can be generalized to all animals with "dimensional advantage".

It also is sometimes quite analogous to human weaponery, see my example of Triceratops. True, a horn is not disposable in the way a sword or spear is, but it is also a distinctly non-vital area, and having the tip of a horn bitten off in a fight (which we know is something that happened, and was survived, see Happ 2008) is far preferable to having a vital area bitten, and also far preferable to having said horn poke you in a vital area. This is less true for skulls, but still not totally irrelevant. If an animal has a longer skull and/or neck (think of the dromaeosaur vs carnivoran comparison already shown above), it will have an easier time dictating the range of the engagement, as well as reaching vital structures without its opponent doing the same in response.

Anyway, so far this is only addressing half of the equation, an advantage in reach, but not an advantage in nimbleness of the attack.

Also, Brown et al 2021 documented face-biting in a wide range of theropods. Since most large (>1.5 tonne) theropods are only really worth comparing to either large mammals/herbivorous dinosaurs or other theropods, this has significant implications for how theropod matchups would go.

Non-lethal face-biting in the context of intraspecific conflict. But likewise, for face-biting it does matter how long your jaws are, and how much of your opponent’s face you will reach while doing so, especially if you intend on using it not just to wrestle with your opponent, but to actually gain a favourable position to deal lethal damage.

The reason I don't take theropod forelimbs that seriously in near-parity fights with other theropods is pretty simple: lack of anterior range of motion.

That is true and relevant as far as initial attacks are concerned, but if we are talking about grappling we are talking about the animals getting close and personal with each other, past the stage of standing in front of each other and trying to get the first bite on the other.
Clearly, to those theropods that retained large, raptorial forelimbs, they must have been useful, otherwise they would not have had the morphology they did, although there are many giant theropods that did reduce the forelimbs to the point of being vestigial (perhaps supporting the previously uttered statement that grappling was a less effective strategy at large sizes).
Anterior range of motion (and how anterior relative to the rest of the animal that would put the hands) also needs to be considered in the context of how the animal held its body (the above assumes scapular orientations reflecting a neutral, horizontal body posture). Theropods didn’t necessarily fight with their bodies stretched out horizontally, especially since raising the tail and body and pulling back the neck would lower the rotational inertia significantly (based on my experiments with plausibly reposing my juvenile Plateosaurus, which is in many ways a favourable comparison to a theropod, adopting a realistic "semi-erect body, raised tail"-posture would lower rotational inertia by ~ 20%). And if their torsos were held more upright than the neutral posture, that would also greatly increase the odds of the arms being the first thing to make contact with the opponent. I think we’re sometimes overcompensating a bit in terms of how "static" we assume theropods would have fought. Of course these aren’t animals that would run circles around each other, but just standing there in a static posture biting each other’s face also probably isn’t everything they did.

For intraspecific fighting in something like Allosaurus or megalosauroids, I could even imagine them doing something like komodo-dragon-esque wrestling matches involving their forelimbs and occasional biting (depending, of course, on how lethal these conflicts were intended to be).

---
Happ, J. 2008. An analysis of predator-prey behavior in a head-to-head encounter between Tyrannosaurus rex and Triceratops. Tyrannosaurus rex the Tyrant king: 355–370.

[lionclaws]

Sept 25, 2023 3:02:51 GMT 5 Supercommunist said:

Sept 24, 2023 15:04:45 GMT 5 Infinity Blade said:

Interesting. I always thought that big headed predators (eg. many theropods, hyaenodonts, entelodonts, etc.) could prevent getting grappled in the first place with their huge jaws, but I didn’t realize even a hyena could do so against a much larger lion. Similarly, I’ve seen a video where a zebra gets its neck restrained by a lioness, but the zebra was able to nip her flank with its front teeth. It ultimately escaped.

m.youtube.com/watch?v=kXwG-ms63X8

Also, in that cougar-wolf fight that happened in B.C. several years ago, the wolf ultimately lost, but initially both animals were said to have had a grip on each other in their jaws. It was only after the wolf was startled by the observer that it let go of the cougar and tried to flee, allowing the cougar to counterattack and kill the wolf.

www.ctvnews.ca/mobile/canada/cougar-vs-wolf-unreal-battle-caught-on-video-in-b-c-1.2411625

Obviously not saying grappling isn’t useful, it certainly is, but lots of people on CF used to act as if a non-grappling predator caught by a grappler was automatically screwed. That doesn’t appear to be completely true.

Preventing a bite during a frontal engagements seems to be difficult in general.

Coyote bites cougar.

www.youtube.com/watch?v=uKpL8213WE4&ab_channel=barryk.

Otter bites lioness.

www.youtube.com/watch?v=yFV4SbZv10s&ab_channel=EarthTouch

Dog bites leopard.

Jaguars in general seem wary when attacking peccaries from the front.

www.youtube.com/watch?v=a0KWhLUSC4Y&ab_channel=WBPSHORTS

www.youtube.com/watch?v=ZWExP3KJmRY&ab_channel=SeanKeuroghlian-Eaton

Grappling obviously is very useful against most animals but modern predators mainly prey on animals that use their horns or kicks to defend themselves. If you grab a bull by the head it can't really fight back until it shakes you of since it relies on momentum to deal damage. In constrast,an animal's jaw power isn't diminished just because someone is grabbing you. Sure, it might prevent them from shaking their head or something but the teeth are going to dig in and bites are a lot easier to land in general.

Such things can happen, yes, but they won't always happen.

Let's take a more specific example. Suppose we have a series of fights between Kodiak bears and Rugops primus at weight parity. The bear leads with its paws, Rugops leads with its jaws. There will be instances where the Rugops manages to tag the bear and the bear bleeds out before it can do any serious damage to the theropod. This I freely admit.

But there will also be instances where the initial bite either fails to connect, or only snags part of a paw. What happens in the clinch? Most likely, the two wrestle, the bear takes the theropod to the ground, and crushes its skull like a watermelon under its sheer weight. At which point the end of the fight is a foregone conclusion: the Rugops has been effectively disarmed, will eventually die of its injuries, and is quite likely to be mauled to death on the spot. My contention would be that this latter sort of outcome would be somewhat more common than the former. Not massively so, mind you, perhaps odds of 6:5 in the bear's favor.

It's worth noting that theropods would have needed a chance to move their skulls in order to seriously damage an opponent. In Abelisaurids (and Tyrannosaurus rex) this would have been achieved by lateral "thrashing" motions. In other theropods, it would have been more of a backwards "raking" motion. Either way, if the skull is significantly restrained (say, pinned under 400 kg of irate ursid), the odds of doing serious damage even if the jaws are closed on something important are fairly low.

[lionclaws]

Sept 25, 2023 3:14:27 GMT 5 theropod said:

Are there actually published bite force estimates for non T. rex tyrannosauroids? There might be, but the last time I had a truly comprehensive overview of the theropod literature (back when I made that comparison posted above) that wasn’t the case. If they are higher than the average theropod, then at least it is doubtful if they are higher to such a high degree as to make a truly significant difference for grappling with something (esp. since the teeth and skulls aren’t actually stronger).

I don't think that other tyrannosaurs would have wrestled with prey the way that T rex (and probably abelisaurs) could have. In general, I would say that Rex's "wrestling ability" more than made up for its somewhat lackluster weaponry, but not to such a degree that it would have dramatically outperformed its narrow-toothed relatives in a fight.

they kinda have hacks

Well yes, but that could basically be said for anything that gives one animal an advantage over another animal in some way.

Flight strikes me as a more comprehensive advantage than flexible forelimbs or the like.

The counterargument I'd make against the idea of "dimensional advantage" is that a) it's not particularly analogous to human weaponry, as the weaponry of an animal is part of it, whereas a weapon is a semi-disposable tool that we can afford to be damaged, and b) it doesn't hold up in real life examples. In general, a lankier, less heavily built animal will lose to one with a more compact bauplan, all things being equal.

Are there any actual real life examples where the condition "all else being equal" is met though? An example that comes up often, to the point of being quite annoying is leopard vs cheetah, but this is not a good analogy for the kind of differences I outined; a cheetah has a shorter skull than a leopard, not a longer one, and it also has semi-retractable claws and inferior limb dexterity, putting it at a grappling disadvantage due to more than simple robusticity or lack thereof, all that while not having any weaponery that would make it less reliant on grappling (quite the contrary).

Did it never strike you that the superior dexterity of the leopard might be precisely because of its more compact build?

Here's some biomechanics I picked up on Carnivora. Because muscles aren't infinitely contractible, the range of motion of a limb is proportional to the length of the muscle and inversely proportional to the distance between the relevant joint and the muscle's insertion point (the in-lever arm).

As for the force applied by the limb, that's directly proportional to the mass of the muscle and the length of the in-lever arm, while being inversely proportional to the length of the muscle and the length of the out-lever arm.

If you want decent strength over a wide range of motion, you get the best results by decreasing the out-lever arm (total limb length) or by increasing the total muscle mass. Both of which result in a bulkier, more compact animal. You can play with the in-lever arm and the muscle length, but those factors will always lead to increased strength for decreased flexibility, or increased flexibility for decreased strength.

These are not features that can be generalized to all animals with "dimensional advantage".

Well, depends what you mean. For theropods, "out-lever arm" would be something like overall head-and-neck length. Muscle mass would still be muscle mass.

In general, it should be obvious that robusticity is still advantageous.

It also is sometimes quite analogous to human weaponery, see my example of Triceratops. True, a horn is not disposable in the way a sword or spear is, but it is also a distinctly non-vital area, and having the tip of a horn bitten off in a fight (which we know is something that happened, and was survived, see Happ 2008) is far preferable to having a vital area bitten, and also far preferable to having said horn poke you in a vital area.

Sure, but in general, it will take prolonged goring for horns or tusks to kill another animal. Bites (whether targeted crushing bites or generalist slashing bites) are generally more quickly lethal.

This is less true for skulls, but still not totally irrelevant. If an animal has a longer skull and/or neck (think of the dromaeosaur vs carnivoran comparison already shown above), it will have an easier time dictating the range of the engagement, as well as reaching vital structures without its opponent doing the same in response.

In the same way, serious trauma to the snout (say, from a leopard biting hard somewhere in the vicinity of the nasal) will reduce the efficacy of the jaws as a weapon.

Dromaeosaurs, being "four point grapplers," are a bit of a red herring, though, imo. They have both good grappling ability and good weaponry, making them sit in a slightly different place than more "conventional" theropods.

Anyway, so far this is only addressing half of the equation, an advantage in reach, but not an advantage in nimbleness of the attack.

I'm not fully convinced that a theropod would be more nimble with its skull than a felid or ursid would be with its forelimbs to the extent required by the "dimensional advantage" hypothesis.

As for theropod vs theropod matchups, it's worth noting that a more elongate build increases rotational inertia, decreasing nimbleness.

Also, Brown et al 2021 documented face-biting in a wide range of theropods. Since most large (>1.5 tonne) theropods are only really worth comparing to either large mammals/herbivorous dinosaurs or other theropods, this has significant implications for how theropod matchups would go.

Non-lethal face-biting in the context of intraspecific conflict.

These instincts would likely be carried over to interspecific conflict with other theropods.

But likewise, for face-biting it does matter how long your jaws are, and how much of your opponent’s face you will reach while doing so, especially if you intend on using it not just to wrestle with your opponent, but to actually gain a favourable position to deal lethal damage.

I take a slightly different view. In a serious fight, where things escalate from quick snaps to serious "bites with intent," the thing that determines who wins the fight is more or less who gets away with more of their jaw muscles and cranial structure intact.

The reason I don't take theropod forelimbs that seriously in near-parity fights with other theropods is pretty simple: lack of anterior range of motion.

That is true and relevant as far as initial attacks are concerned, but if we are talking about grappling we are talking about the animals getting close and personal with each other, past the stage of standing in front of each other and trying to get the first bite on the other.

By that time, both animals would have exposed their necks to their opponent's jaws. The fight almost certainly ends before the claws can be brought to bear, independent of species.

Clearly, to those theropods that retained large, raptorial forelimbs, they must have been useful, otherwise they would not have had the morphology they did, although there are many giant theropods that did reduce the forelimbs to the point of being vestigial (perhaps supporting the previously uttered statement that grappling was a less effective strategy at large sizes).
Anterior range of motion (and how anterior relative to the rest of the animal that would put the hands) also needs to be considered in the context of how the animal held its body (the above assumes scapular orientations reflecting a neutral, horizontal body posture). Theropods didn’t necessarily fight with their bodies stretched out horizontally, especially since raising the tail and body and pulling back the neck would lower the rotational inertia significantly (based on my experiments with plausibly reposing my juvenile Plateosaurus, which is in many ways a favourable comparison to a theropod, adopting a realistic "semi-erect body, raised tail"-posture would lower rotational inertia by ~ 20%). And if their torsos were held more upright than the neutral posture, that would also greatly increase the odds of the arms being the first thing to make contact with the opponent. I think we’re sometimes overcompensating a bit in terms of how "static" we assume theropods would have fought. Of course these aren’t animals that would run circles around each other, but just standing there in a static posture biting each other’s face also probably isn’t everything they did.

I'd want to see functional morphology of the hip joint in large theropods before I form an opinion on this particular point.

FWIW, my working assumption is that the meathook claws of the carnosaurs were used to capture and dispatch relatively smaller prey, which (when combined with craniocervical adaptations for macropredation) would have allowed the carnosaurs to attempt to hunt pretty much anything in their environment.

For intraspecific fighting in something like Allosaurus or megalosauroids, I could even imagine them doing something like komodo-dragon-esque wrestling matches involving their forelimbs and occasional biting (depending, of course, on how lethal these conflicts were intended to be).

It's certainly a compelling image, but again, I'd need to see some kind of information on the hip-and-tail morphology before I can form an opinion.

EDIT: I see the formatting gore, I'll deal with it later.

[Infinity Blade]

Sept 25, 2023 3:14:27 GMT 5 theropod said:

Are there actually published bite force estimates for non T. rex tyrannosauroids? There might be, but the last time I had a truly comprehensive overview of the theropod literature (back when I made that comparison posted above) that wasn’t the case. If they are higher than the average theropod, then at least it is doubtful if they are higher to such a high degree as to make a truly significant difference for grappling with something (esp. since the teeth and skulls aren’t actually stronger).

I think the closest to this is table 6 in this study (Rowe & Snively, 2021). Granted, half of the specimens in the "tyrannosauroid" column are just T. rex, but the other half are either other tyrannosaurids or one non tyrannosaurid-tyrannosauroid (Dilong), and they have F_Muscle (N) values on the right. Granted, they say muscle force, which could just mean the raw power of the jaw muscles before being translated into actual bite force, but given how the study also says they measured tooth/bite reaction forces (Fig. 4 makes that clear), I'm inclined to think these may be actual bite force figures.

For most analyses, properties of Alligator mandible bone (Porro et al., 2011) were applied to all the specimens, to ensure comparable results. In one model and set of analyses for the large juvenile Tyrannosaurus BMRP 2002.4.1, separate properties for bone, dentine (which makes up most of the teeth of reptiles), and ligaments (Porro et al., 2011) were applied. This analysis assessed the effects of ligaments, which accommodate more strain than bone, on bone stresses and tooth reaction forces.

To apply forces, nodes were selected in the areas where forces were being tested and divided by the total respective estimated muscle force by the total number of nodes selected. Constraints were assigned to restrict free body motion, at the hinges of the jaw and two mesial teeth for both constraints to obtain bite reaction forces.

Sept 25, 2023 4:35:44 GMT 5 lionclaws said:

EDIT: I see the formatting gore, I'll deal with it later.

I'm not sure if this is really helpful advice, but I do want to see what I can do to make formatting easier for you. What I like to do is to first copy and paste the other person's words, and then put "quote" and "/quote" (although with brackets in place of parentheses marks of course) at the beginning and the end, respectively. You can then double check and triple check as many times as you see fit to make sure none of your own words are between an unwanted quote bracket.

Now, if you want to make it known that they've been quoted, you could alternatively 1) click "quote" on their post, 2) copy the part that says "quote timestamp="1695593667" source="/post/65066/thread" author="@insert other guy's username here"" (obviously this will be in brackets instead of quotation marks), 3) post their words immediately after this, and 4) right after their last word/punctuation mark you close with "/quote" (again, with brackets instead of quotation marks).


As for the discussion (especially that between biters and grapplers), I do have my own personal thoughts, I just gotta decide if I want to jump in the fray or if I'm too lazy and let you guys do the talking this time around.[/quote]

[theropod]

Sept 25, 2023 4:35:44 GMT 5 lionclaws said:

Did it never strike you that the superior dexterity of the leopard might be precisely because of its more compact build?

No, why would it?

That longer limbs tend to be less flexible than shorter ones is a correlation, but not a causation. A cheetah’s limbs are not less flexible than a leopards because they are longer, they are less flexible because they are specialized for running (the same reason why they are longer, but not a result of them being longer).

But also, I’m not primarily talking about cursorial vs non-cursorial animals here. If anything, something like a Giganotosaurus or a Triceratops is less cursorial than a Tyrannosaurus, not more (which a cheetah is when compared to a leopard).

Here's some biomechanics I picked up on Carnivora. Because muscles aren't infinitely contractible, the range of motion of a limb is proportional to the length of the muscle and inversely proportional to the distance between the relevant joint and the muscle's insertion point (the in-lever arm).

That is the range of motion in the plane of action of that muscle, and barring any additional limitations that may be imposed by joint mobility or other osseous stops, which is not a realistic assumption in a lot of cases. But this tells you little about dexterity, as based on only this criterium a more cursorial animal might actually have the larger ranges of motion due to having shorter in-levers. But that’s likely a lot less relevant to dexterity than other aspects of flexibility, such as the ability to pronate or supinate the forearms and the fine motor control of the digits, enabling them to grasp (with the aid of claws).

As for the force applied by the limb, that's directly proportional to the mass of the muscle and the length of the in-lever arm, while being inversely proportional to the length of the muscle and the length of the out-lever arm.

Not completely correct, or a bit misleading anyway. The force is proportional to the physiological cross-sectional area, not the mass, and the mechanical advantage (in-lever/out-lever). The length of the muscle is relevant for the length of its power stroke, and as you point out above, thus figures into the range of motion, but it is not related to the force. What is correct is that the PCSA, and thus the contractile force, is related (inversely) to muscle fiber length (shorter fibers=more fibers for a given volume=greater PCSA), which can vary widely for muscles of the same length (although it tends to be very loosely correlated)

If you want decent strength over a wide range of motion, you get the best results by decreasing the out-lever arm (total limb length) or by increasing the total muscle mass. Both of which result in a bulkier, more compact animal. You can play with the in-lever arm and the muscle length, but those factors will always lead to increased strength for decreased flexibility, or increased flexibility for decreased strength.

A longer muscle of equal cross-section with the same mechanical advantage could generate the same force over the same angular range of motion as a shorter muscle with the same cross-section. Only that range of motion will actually be greater dimensionally if both the in- and the outlever are longer (keeping MA the same, but increasing the distance by increasing the power-stroke of the muscle).

For the record, that’s exactly what I think was the case for Allosauroid necks vs Tyrannosaurid necks, although I am not saying that they were as strong in every motion (certainly not as strong in lateroflexion, but probably at least as strong in ventroflexion). They are (osteologically) more flexible and longer, with longer muscles that likely have a longer power-stroke, and at least some of those muscles have long moment arms, which would mean the out-lever force these muscles could produce would be large as well. Meaning the result is a large strike range and quick movements of the head.

Both of which result in a bulkier, more compact animal.

Also it might be more precise to say this (usually) results in an animal with stockier limbs, or whatever structure we are currently discussing (neck, tail, whatever) being stockier, not necessarily a stockier animal overall.
Allosauroids and Megalosauroids have considerably stockier distal limb segments than tyrannosaurs, but their torsos are simultaneously less stocky. Animals don’t all conform to the "more stocky in every regard–more gracile in every regard"-dichotomy. Built of different body regions can influence and correlate with one another to some extent (for example it’s likely that the wide chest and large scapula of Tyrannosaurus have something to do with being an origination site for neck muscles, especially the lateroflexive ones), but not necessarily always.
Canids don’t seem to have more slender torsos than Felids (if anything they look more compact), but they still have more slender, cursorial limbs with less dexterity for grappling–so how bulky their torsos are likely holds very little advantage for their grappling ability. Mustelids on the other hand often have very elongated torsos, which likewise doesn’t mean they are weak grapplers. In fact a chicken has a far bulkier body than a pine marten, but I’ll wager nobody would suggest the chicken would overpower the pine-marten in a fight.

Well, depends what you mean. For theropods, "out-lever arm" would be something like overall head-and-neck length. Muscle mass would still be muscle mass.

see above.

Sure, but in general, it will take prolonged goring for horns or tusks to kill another animal. Bites (whether targeted crushing bites or generalist slashing bites) are generally more quickly lethal.

I’m not really convinced of that.
I’ve seen plenty of footage of animals biting each other, even on supposedly vital areas, and taking a long time to actually kill or incapacitate one another. On the other hand being stabbed in the vitals with a horn is literally like getting stabbed with a knife or a spear. Not necessarily instantly lethal either, but (unlike a bite) it doesn’t take prolonged contact at all in order to kill.
I mean, most big cats literally rely on constriction to kill most prey their own size or larger, because they apparently would struggle to deal sufficient mechanical damage otherwise. Sabre-toothed cats literally evolved sabre-teeth in order to get around this issue and be able to kill efficiently through exsanguination and avoid this prolonged contact with their prey. And in the end, being stabbed by a sabre-tooth is not that dissimilar to being stabbed by a horn, although admittedly the horn doesn’t have a cutting edge, making it inferior at exsanguination (though the horn is longer and much more capable of penetrating internal organs).

In the same way, serious trauma to the snout (say, from a leopard biting hard somewhere in the vicinity of the nasal) will reduce the efficacy of the jaws as a weapon.

It would depend on how serious that trauma would be. If the snout were completely crushed, sure. But a few tooth puncture wounds to a nasal or maxilla from canines might not be sufficient to put the jaws out of action, especially considering, as you mentioned, many theropods were quite used to having their faces bitten (and likely by jaws capable of causing more extensive damage overall than those of your average cat or bear).

Dromaeosaurs, being "four point grapplers," are a bit of a red herring, though, imo. They have both good grappling ability and good weaponry, making them sit in a slightly different place than more "conventional" theropods.

No argument from me there, though it is important to keep in mind we have to consider these animals in their respective weight classes. There are no Dromaeosaurs in the size classes of Allosaurus or Tyrannosaurus, and if there were, they might not be the same morphologically as their smaller relatives due to constraints imposed by size.

I'm not fully convinced that a theropod would be more nimble with its skull than a felid or ursid would be with its forelimbs to the extent required by the "dimensional advantage" hypothesis.

Probably not (although that’s not a fair comparison, as its skull, while less nimble than the forelimbs, would be able to cause much more damage in exchange), but an Allosauroid’s (or gracile-skulled tyrannosaurid) skull would likely be much more nimble (read: able to strike much faster and further) than either a cat’s (though that’s more a result of the cat’s short neck and skull) or a Tyrannosaurus (on account of the latter’s skull and neck being far heavier).

As for theropod vs theropod matchups, it's worth noting that a more elongate build increases rotational inertia, decreasing nimbleness.

Rotational inertia of the whole body turning around the center of mass or the hip yes.
While there are some details in the Snively et al. study on this matter that I take issue with (for example they estimate a much higher rotational inertia for the Giganotosaurus holotype than for T. rex sue, which is only a few centimetres shorter, but much heavier, with much of that mass concentrated distally from the center of rotation in the massive skull and neck. I have been unable to replicate this based on Hartman’s multiview reconstructions, my results for the same models would suggest a considerably lower rotational inertia for MUCPv-Ch1 than for sue, even though I don’t doubt that at the same mass Giganotosaurus would indeed have the higher inertia), having the same mass spread out over a greater length will certainly increase rotational inertia.

But that’s not the case here. We are not talking about a stiff rod, or something that can be modelled like a stiff rod, that is equal in mass, but differs in length. We are talking about a flexible structure muscled throughout (the neck), with each intervertebral joint and its muscles contributing to the motion, which makes simulating it much more complex, and the overall mass is not the same, it is considerably less (meaning the overall mass that is to be moved, the head, is less for the allosauroid, or most other therpods, than it is for the T. rex). Now Tyrannosaurus may have been able to compensate for that by being able to generate larger torque, but likely only in lateroflexion, as its musculature for dorso- or ventroflexion (i.e. the musculature needed to re- or protract the head and actually strike with it) is not especially developed when compared to other theropods.

These instincts would likely be carried over to interspecific conflict with other theropods.

They likely would, but fighting and killing are not the same things, and the behaviours that make an animal good at one might not necessarily make it good at the other.

There are plenty of examples of animals that are powerful fighters, but struggle to actually kill, all the more so if faced with an opponent that they don’t have a significant physical advantage over.

For example bears are excellent grapplers and fighters, but would likely find themselves in a fairly sticky situation if they were ever faced with an opponent too large to overcome with simple strength alone, and simultaneously well-armed enough to pose a mortal thread to them. But there are not that many animals that bears coexist with today that would fit this bill.

Chimpanzees likewise are powerful animals and very good grapplers, but not very good killers. The regions you target and the equipment you need while fighting to subdue simply aren’t the same as the ones relevant when fighting to kill. I suspect something similar may be the case with theropod face-biting, which after all is documented to have been non-lethal. It makes sense for the face to be the first thing to target in any sort of confrontation, and in a non-lethal ritualized fight where both animals benefit from reducing the risk of death, they may well keep it at that. But that doesn’t mean biting the face would be the "end goal" if the animals were to fight to kill one another.

I take a slightly different view. In a serious fight, where things escalate from quick snaps to serious "bites with intent," the thing that determines who wins the fight is more or less who gets away with more of their jaw muscles and cranial structure intact.

And what if not the ability to reach more of those structures without having your opponent reach yours would determine this outcome?

Just like a longer spear allows a human to stab another human wielding a shorter weapon before said human can seriously injure them, longer jaws could also allow an animal biting another animal’s face to slash its jaw muscles or other important structures while keeping it’s own out of harm’s way by comparison. And a longer neck, bearing in mind the ability to quickly pro- and retract it, simply offers more options for angles of attack or evasion to gain a favourable position in which you might bite your opponent (whether we’re taking about skull- and face biting or something else) while not being bitten yourself.

By that time, both animals would have exposed their necks to their opponent's jaws. The fight almost certainly ends before the claws can be brought to bear, independent of species.

Depends on the posture, but clearly any grappling ability will be irrelevant if one animal can land a lethal bite before it comes to grappling; it seems that at this point you actually do acknowledge the relevance of the jaws’ greater reach, albeit only in comparing them to the forelimbs and not to each other.

FWIW, my working assumption is that the meathook claws of the carnosaurs were used to capture and dispatch relatively smaller prey, which (when combined with craniocervical adaptations for macropredation) would have allowed the carnosaurs to attempt to hunt pretty much anything in their environment.

Considering the limited reach of these forelimbs that you pointed out yourself, why would such forelimbs be more advantageous for catching fast-moving, small prey as compared to the jaws (which, as I pointed out, were likely quite nimble and had good range of motion, independent of having to slowly and laboriously turn the entire body)?

Taking the example of Allosaurus, certainly it would have had an easier time snatching a small prey item in its jaws than maneuvering its body so as to bring the forelimbs into range. Whereas with a larger, taller prey item, not only would raising its body posture also raise the forelimbs (not useful for small prey, but useful for large prey), but there would also be a much higher chance that grappling would even be necessary after first contact with the jaws.

I'd want to see functional morphology of the hip joint in large theropods before I form an opinion on this particular point.

What I’ve seen so far is this:

Direct osteological evidence for elevated trunk posture during running comes from the structure of the acetabulum in allosaurids (Molnar and Farlow, 1990), Sinraptor dongi (Currie and Zhao, 1993), Torvosaurus (Galton and Jensen, 1979) and dromaeosaurs (Norell and Makovicky, 1997). In these theropods, and possibly others, the most robust aspect of the joint surface is located not on the dorsal surface of the acetabulum, as would be expected if the long axis of the ilium were held horizontal during running, but more cranially and extends onto the pubic peduncle.

from: Carrier, D.R., Walter, R.M. and Lee, D.V. 2001. Influence of rotational inertia on turning performance of theropod dinosaurs: clues from humans with increased rotational inertia. Journal of Experimental Biology 204 (22): 3917–3926.


I think the issue deserves further study (as I wrote, I did some modelling for the rotational inertia in Plateosaurus as a test of the influence of this factor, what I found was an axial rotational inertia around the COM of 4.85 for the standard, horizontal model, and 3.86 for a semi-erect, raised-tail model, which suggests the benefits from that perspective alone would definitely be noteworthy). I might look further into this question in the future.

[Supercommunist]

Such things can happen, yes, but they won't always happen.

Let's take a more specific example. Suppose we have a series of fights between Kodiak bears and Rugops primus at weight parity. The bear leads with its paws, Rugops leads with its jaws. There will be instances where the Rugops manages to tag the bear and the bear bleeds out before it can do any serious damage to the theropod. This I freely admit.

But there will also be instances where the initial bite either fails to connect, or only snags part of a paw. What happens in the clinch? Most likely, the two wrestle, the bear takes the theropod to the ground, and crushes its skull like a watermelon under its sheer weight. At which point the end of the fight is a foregone conclusion: the Rugops has been effectively disarmed, will eventually die of its injuries, and is quite likely to be mauled to death on the spot. My contention would be that this latter sort of outcome would be somewhat more common than the former. Not massively so, mind you, perhaps odds of 6:5 in the bear's favor.

It's worth noting that theropods would have needed a chance to move their skulls in order to seriously damage an opponent. In Abelisaurids (and Tyrannosaurus rex) this would have been achieved by lateral "thrashing" motions. In other theropods, it would have been more of a backwards "raking" motion. Either way, if the skull is significantly restrained (say, pinned under 400 kg of irate ursid), the odds of doing serious damage even if the jaws are closed on something important are fairly low.

Some animals possess teeth so sharp they don't really require much head shaking to inflict serious blood loss.

Crocodile monitors which don't have serrations on their teeth are infamous for how easily they can cut flesh:

3:49 according to this man a mere warning snap was all it took for this crocodile monitor to make him leak like a faucet.

www.youtube.com/watch?v=R6bl1dXN9iI&ab_channel=KampKenan

Another man describes his experience with crocodile monitor, stating that a nip can inflict an injury that would have required about 15 stiches.

2:18

www.youtube.com/watch?v=sv_xqfMJ1m4&ab_channel=CheckingInClips

There is also this very graphic video of a bull shark ripping off a mans calf with horrific ease. Warning very NSFW. View at your own discretion.

www.youtube.com/watch?v=mP6uHuIEMoU&ab_channel=Discovery

Given that theropod had massive heads I think it is likely they had more powerful necks than something like a wolf at parity. Theropods also probably had pretty nasty kicks.

Although I think ratites, are overrated there is a video of an emu that managed to absolutely shred a man's pants while it was flailing its legs around. If he shorts on his legs would have been sliced up.

www.youtube.com/watch?v=vaV0tzd2hVg&ab_channel=AbstractMindset

In addition, theropods being bipedal animals are naturally taller than similar sized carnivorans while they are in their default quadruped stance so in order to grab them in a headlock they would have to rear up to a higher degree. Being in this position would make them less balanced than theropods that actually primarily walk on two legs.

IB has also posted ostriches nearly killing men with a single kick and a legit case of an ostrich killing a sub adult lion. If a bear tried to fight a macropredatory theropod I think it needs to avoid taking a serious bite at all, otherwise it would rapidly weaken or outright bleed to death while it is wrestling the theropod.

As I said in an earlier post, avoiding a bite is difficult. I am not sure how flexible theropod necks are compared to komodos, but ifs anywhere near as flexible they would be able to bite back from very awkward and unideal angles

6:10



Also notice the visible bleeding in the armpit region despite hown short this scuffle was? Recent studies have found that komodos have specalized armor designed to protect them from each others bites, yet the female still managed to penetrate his flesh and inflicted more bleeding you typically see in extended cat or bear fights.

news.utexas.edu/2019/09/12/elaborate-komodo-dragon-armor-defends-against-other-dragons/

I also think it's worth nothing fights between carnivorans are often long. I've seen videos of lions snapping another lions spine and there are cases of wolves killing each other with skull bits but there are cases of multiple lions taking over an hour to kill another lion. IIRC it took Kinkytail an hour to die after he was attacked by 4 lions and actual footage of wolf fights seem to be prolonged affairs.

www.youtube.com/watch?v=VcTsWXOZMzQ&t=8s&ab_channel=NatureonPBS

In contrast, shark bites are usually short, and brutal affairs. Granted I haven't seen footage of similar sized sharks fighting but you don't see videos of wolves biting off fox limbs or leopard cutting servals, carcals, or wildcats in half.



I don't think a non-saber cat or bear would be able to kill a similar sized theropod very quickly on most occasions so that's a lot of time to slip up and get bit.

[lionclaws]

Well. I was working on a response to theropod. The internet ate it. I'll get another one in the works when I can, I have choir tonight.

[lionclaws]

Sept 25, 2023 15:39:58 GMT 5 theropod said:

Sept 25, 2023 4:35:44 GMT 5 lionclaws said:

Did it never strike you that the superior dexterity of the leopard might be precisely because of its more compact build?

No, why would it?

That longer limbs tend to be less flexible than shorter ones is a correlation, but not a causation. A cheetah’s limbs are not less flexible than a leopards because they are longer, they are less flexible because they are specialized for running (the same reason why they are longer, but not a result of them being longer).

But also, I’m not primarily talking about cursorial vs non-cursorial animals here. If anything, something like a Giganotosaurus or a Triceratops is less cursorial than a Tyrannosaurus, not more (which a cheetah is when compared to a leopard).

In general, cursoriality imposes different constraints on mammalian carnivores than on theropods. Moreover, I would question the degree to which cursoriality influenced the flexibility even of theropod hindlimbs. If tyrannosaurs were primarily adapted for forward-backward movement to the exclusion of more agile and flexible side-to-side movements, we would expect the ratio between anteriposterior and mediolateral femoral "diameter" to be fairly high compared to carnosaurs. This holds for some specimens, but not all, or even most.

All data taken from Campione et al 2014:

Carnotaurus
MACN-CH 894......1.01


Allosaurus
AMNH 680............0.897

Acrocanthosaurus
NCSM 14345........0.866

Giganotosaurus
MUCPv-CH 1........0.873


Albertosaurus
ROM 807...............0.689

Gorgosaurus
CMN 530...............1.29

Tyrannosaurus
BHI 3033...............1.22
MOR 555...............0.826
FMNH PR 2081.....0.637


In general, tyrannosaurs seem to have two "clusters," one with AP/ML values above 1.2, and one with AP/ML values below 0.85. Carnosaurs tend to cluster in the 0.85-0.90 range. Carnotaurus (highly cursorial among theropods) had a fairly round femur. Even granting cursoriality for Rex, without the limbs playing a significant role in prey capture (as in mammals) or compromises in agility (which would predict a uniformly high AP/ML diameter for tyrannosaurs), it's not obvious how that would translate to a disadvantage, as the primary disadvantages for mammalian carnivores don't appear to apply.

Here's some biomechanics I picked up on Carnivora. Because muscles aren't infinitely contractible, the range of motion of a limb is proportional to the length of the muscle and inversely proportional to the distance between the relevant joint and the muscle's insertion point (the in-lever arm).

That is the range of motion in the plane of action of that muscle, and barring any additional limitations that may be imposed by joint mobility or other osseous stops, which is not a realistic assumption in a lot of cases. But this tells you little about dexterity, as based on only this criterium a more cursorial animal might actually have the larger ranges of motion due to having shorter in-levers. But that’s likely a lot less relevant to dexterity than other aspects of flexibility, such as the ability to pronate or supinate the forearms and the fine motor control of the digits, enabling them to grasp (with the aid of claws).

As for the force applied by the limb, that's directly proportional to the mass of the muscle and the length of the in-lever arm, while being inversely proportional to the length of the muscle and the length of the out-lever arm.

Not completely correct, or a bit misleading anyway. The force is proportional to the physiological cross-sectional area, not the mass, and the mechanical advantage (in-lever/out-lever). The length of the muscle is relevant for the length of its power stroke, and as you point out above, thus figures into the range of motion, but it is not related to the force. What is correct is that the PCSA, and thus the contractile force, is related (inversely) to muscle fiber length (shorter fibers=more fibers for a given volume=greater PCSA), which can vary widely for muscles of the same length (although it tends to be very loosely correlated)

I am, of course, speaking in broad generalities - as one must when assessing the relative value of "dimensional advantage" vs robusticity of build.

In particular, I am assuming that all muscles have parallel fibers (or are, at any rate, equally pennate).

All things considered, all levers throughout the body benefit from increased muscle mass and decreased out-lever. Everything else - pennate vs parallel fiber arrangement, in-lever, muscle length - is, more or less, a tradeoff between flexibility and strength. I don't see anything that contradicts that statement in the general sense.

If you want decent strength over a wide range of motion, you get the best results by decreasing the out-lever arm (total limb length) or by increasing the total muscle mass. Both of which result in a bulkier, more compact animal. You can play with the in-lever arm and the muscle length, but those factors will always lead to increased strength for decreased flexibility, or increased flexibility for decreased strength.

A longer muscle of equal cross-section with the same mechanical advantage could generate the same force over the same angular range of motion as a shorter muscle with the same cross-section. Only that range of motion will actually be greater dimensionally if both the in- and the outlever are longer (keeping MA the same, but increasing the distance by increasing the power-stroke of the muscle).

This presumes that the ratio between in-lever and fiber length is constant, which it may not be.

For the record, that’s exactly what I think was the case for Allosauroid necks vs Tyrannosaurid necks, although I am not saying that they were as strong in every motion (certainly not as strong in lateroflexion, but probably at least as strong in ventroflexion). They are (osteologically) more flexible and longer, with longer muscles that likely have a longer power-stroke, and at least some of those muscles have long moment arms, which would mean the out-lever force these muscles could produce would be large as well. Meaning the result is a large strike range and quick movements of the head.

I certainly agree that Tyrannosaurus rex specifically (and, to a lesser degree, tyrannosaurs generally) prioritized strength over flexibility. I'm not as confident about the "equal cross-sectional area" thing, given what I've read (which is, admittedly, probably less than you have).

In general, the biggest difference seems to be the in-lever arm, which is (with the exception of ventroflexion) larger in tyrannosaurs.

Both of which result in a bulkier, more compact animal.

Also it might be more precise to say this (usually) results in an animal with stockier limbs, or whatever structure we are currently discussing (neck, tail, whatever) being stockier, not necessarily a stockier animal overall.
Allosauroids and Megalosauroids have considerably stockier distal limb segments than tyrannosaurs, but their torsos are simultaneously less stocky. Animals don’t all conform to the "more stocky in every regard–more gracile in every regard"-dichotomy. Built of different body regions can influence and correlate with one another to some extent (for example it’s likely that the wide chest and large scapula of Tyrannosaurus have something to do with being an origination site for neck muscles, especially the lateroflexive ones), but not necessarily always.
Canids don’t seem to have more slender torsos than Felids (if anything they look more compact), but they still have more slender, cursorial limbs with less dexterity for grappling–so how bulky their torsos are likely holds very little advantage for their grappling ability. Mustelids on the other hand often have very elongated torsos, which likewise doesn’t mean they are weak grapplers. In fact a chicken has a far bulkier body than a pine marten, but I’ll wager nobody would suggest the chicken would overpower the pine-marten in a fight.

Fair points all, but if what we're talking about is the general utility of "compactness" vs the general utility of "dimensional advantage" in a fighter, it seems pretty obvious that dimensional advantage is less of an advantage than it appears to be.

If there's a small difference (tyrannosaur vs carnosaur), then there will still be vulnerabilities exposed for the "dimensionally larger" creature if it attempts to access "weak spots" on its opponent. By the time a Giganotosaurus or Carcharodontosaurus has a good chance of landing a bite on a Tyrannosaurus' neck, the whole of its own skull will be exposed to the latter's bite.

If there's a large difference (adzarchid vs pantherine cat), then the "dimensionally larger" animal has too little mass spread out over too large a frame, and will almost certainly crumple like a house of cards when the two animals collide. Is it possible that the long beak could be used as a spear to kill the cat? Sure. But it seems orders of magnitude more likely for the stiff, elongated pterosaur to wind up being outmaneuvered, overpowered, broken, and killed.

Sure, but in general, it will take prolonged goring for horns or tusks to kill another animal. Bites (whether targeted crushing bites or generalist slashing bites) are generally more quickly lethal.

I’m not really convinced of that.
I’ve seen plenty of footage of animals biting each other, even on supposedly vital areas, and taking a long time to actually kill or incapacitate one another. On the other hand being stabbed in the vitals with a horn is literally like getting stabbed with a knife or a spear. Not necessarily instantly lethal either, but (unlike a bite) it doesn’t take prolonged contact at all in order to kill.

I may have expressed myself poorly.

In general, it takes one good bite (however prolonged) for a well-armed carnivore to kill its prey (which may well be larger than it), whereas elephants can stab each other 20+ times before a fatal injury is dealt. 

This is a significant difference.

With that sort of performance, I'm not sure a Triceratops could kill Acrocanthosaurus reliably in a head-to-head, much less T-rex.

In the same way, serious trauma to the snout (say, from a leopard biting hard somewhere in the vicinity of the nasal) will reduce the efficacy of the jaws as a weapon.

It would depend on how serious that trauma would be. If the snout were completely crushed, sure. But a few tooth puncture wounds to a nasal or maxilla from canines might not be sufficient to put the jaws out of action,

With how lightly built most theropod skulls were, big cats would probably be able to do more than merely puncture the nasal. Bears, it's a different story (at equal weights), but cats? Nasal+maxilla would be a hard ask, but completely breaking the nasal seems within the realm of possibility.

Additionally, as previously pointed out, mammalian predators tend to "bite and hold" rather than "bite and release."

especially considering, as you mentioned, many theropods were quite used to having their faces bitten (and likely by jaws capable of causing more extensive damage overall than those of your average cat or bear).

Depends on where the bite occurs.

Most theropods had low bite forces for their size, but bladelike teeth capable of causing massive soft tissue damage. The skull doesn't have that much soft tissue.

Dromaeosaurs, being "four point grapplers," are a bit of a red herring, though, imo. They have both good grappling ability and good weaponry, making them sit in a slightly different place than more "conventional" theropods.

No argument from me there, though it is important to keep in mind we have to consider these animals in their respective weight classes. There are no Dromaeosaurs in the size classes of Allosaurus or Tyrannosaurus, and if there were, they might not be the same morphologically as their smaller relatives due to constraints imposed by size.

A fair point.

I'm not fully convinced that a theropod would be more nimble with its skull than a felid or ursid would be with its forelimbs to the extent required by the "dimensional advantage" hypothesis.

Probably not (although that’s not a fair comparison, as its skull, while less nimble than the forelimbs, would be able to cause much more damage in exchange),

It is an entirely fair comparison, as the nimbleness of the paws correlates strongly with the likelihood of it being able to gain control over the theropod before either side can start "causing damage."

The theropod strategy against a bear or cat would be to cause sufficient damage before being outgrappled.

The ursid/feline strategy against a non-dromaeosaur theropod would be to get and maintain control of the dinosaur and prevent it from effectively "causing damage."

Two paws on the cheeks/neck and a bite to the snout strikes me as an effective way to deal with a theropod at weight parity, and a strategy that is fairly typical for both felines and bears.

As for theropod vs theropod matchups, it's worth noting that a more elongate build increases rotational inertia, decreasing nimbleness.

Rotational inertia of the whole body turning around the center of mass or the hip yes.
While there are some details in the Snively et al. study on this matter that I take issue with (for example they estimate a much higher rotational inertia for the Giganotosaurus holotype than for T. rex sue, which is only a few centimetres shorter, but much heavier, with much of that mass concentrated distally from the center of rotation in the massive skull and neck. I have been unable to replicate this based on Hartman’s multiview reconstructions, my results for the same models would suggest a considerably lower rotational inertia for MUCPv-Ch1 than for sue, even though I don’t doubt that at the same mass Giganotosaurus would indeed have the higher inertia),

Looking at the citations, they were using a combination of models. Hartman's was one of them, but they were also looking at Paul (2010), Coria and Currie (2002), amd Persons and Currie (2011a&b).

But that’s not the case here. We are not talking about a stiff rod, or something that can be modelled like a stiff rod, that is equal in mass, but differs in length. We are talking about a flexible structure muscled throughout (the neck), with each intervertebral joint and its muscles contributing to the motion, which makes simulating it much more complex, and the overall mass is not the same, it is considerably less (meaning the overall mass that is to be moved, the head, is less for the allosauroid, or most other therpods, than it is for the T. rex). Now Tyrannosaurus may have been able to compensate for that by being able to generate larger torque, but likely only in lateroflexion, as its musculature for dorso- or ventroflexion (i.e. the musculature needed to re- or protract the head and actually strike with it) is not especially developed when compared to other theropods.

Dorsoflexion? Tyrannosaurs still seem to "stand out" with respect to it, based on the craniocervical dynamics study I posted earlier. 

As for ventroflexion, they could easily rely on the weight of their own head to deliver downward blows. Muscle is expensive, after all.

In general, I certainly think that Tyrannosaurus would have had a reduced range of motion, but I'm not convinced that it would have been much slower - or at least, slow enough to make a difference.

But we've drifted a ways from the comparative merits of robusticity and "dimensional advantage" by the time we're looking at details of craniocervical morphology.

A detailed examination of my views on Tyrannosaurus vs other theropods will have to wait until I make my post on the relevant interspecific conflict thread.

These instincts would likely be carried over to interspecific conflict with other theropods.

They likely would, but fighting and killing are not the same things, and the behaviours that make an animal good at one might not necessarily make it good at the other.

There are plenty of examples of animals that are powerful fighters, but struggle to actually kill, all the more so if faced with an opponent that they don’t have a significant physical advantage over.

I make a similar distinction, but draw the opposite conclusion.

An animal can be the best killer in the world, but if it doesn't have the fighting ability to back it up - if it isn't prepared to position itself to avoid being injured while dispatching its opponent - it will generally lose to a less effective killer that is prepared to do just that. 

There are caveats, of course. The "fighter" has to have demonstrated the ability to dispatch animals of similar size to itself in an effective manner.

For example bears are excellent grapplers and fighters, but would likely find themselves in a fairly sticky situation if they were ever faced with an opponent too large to overcome with simple strength alone, and simultaneously well-armed enough to pose a mortal thread to them. But there are not that many animals that bears coexist with today that would fit this bill.

Bears have a reasonable track record against, eg, Iberian fighting bulls (the fight overseers typically had to break up the fight periodically to ensure the bear didn't simply overwhelm and overpower the bull in a boring wrestling match). Bites were aimed to the skull and spine, for control and dispatch respectively. Bears are reasonably capable killers, and excellent fighters, which is why I favor them over a wide range of similarly sized opponents.

Chimpanzees likewise are powerful animals and very good grapplers, but not very good killers. The regions you target and the equipment you need while fighting to subdue simply aren’t the same as the ones relevant when fighting to kill.

Comparing bears to apes does dirt on bears and exaggerates the capabilities of apes.

I suspect something similar may be the case with theropod face-biting, which after all is documented to have been non-lethal. It makes sense for the face to be the first thing to target in any sort of confrontation, and in a non-lethal ritualized fight where both animals benefit from reducing the risk of death, they may well keep it at that. But that doesn’t mean biting the face would be the "end goal" if the animals were to fight to kill one another.

Assuming realistic behaviors on the part of both parties (eg, a positive phobia of exposing the neck to a similarly armed opponent), I would presume the face and skull to be the primary available targets in most theropod v theropod matchups. The neck is just too vulnerable to xiphodont dentition for it to be otherwise. 

These would be fights of dynamic maneuver, both in terms of footwork and "neckwork," with footwork generally being more relevant for controlling distance, and neckwork being more relevant for the final strike. Add to this the probable intelligence of large theropods (comparable to/in excess of that of a rhesus macaque), and we have the interplay of snap and counter-snap, feinting, etc. etc.

I take a slightly different view. In a serious fight, where things escalate from quick snaps to serious "bites with intent," the thing that determines who wins the fight is more or less who gets away with more of their jaw muscles and cranial structure intact.

And what if not the ability to reach more of those structures without having your opponent reach yours would determine this outcome?

Just like a longer spear allows a human to stab another human wielding a shorter weapon before said human can seriously injure them, longer jaws could also allow an animal biting another animal’s face to slash its jaw muscles or other important structures while keeping it’s own out of harm’s way by comparison. And a longer neck, bearing in mind the ability to quickly pro- and retract it, simply offers more options for angles of attack or evasion to gain a favourable position in which you might bite your opponent (whether we’re taking about skull- and face biting or something else) while not being bitten yourself.

Again, I don't want to get too deep down the Tyrannosaurus rex vs [insert carcharodontosaur] rabbit hole quite yet, but I don't see a 20-30 cm difference in skull length being quite as decisive as you make it out to be.

By that time, both animals would have exposed their necks to their opponent's jaws. The fight almost certainly ends before the claws can be brought to bear, independent of species.

Depends on the posture, but clearly any grappling ability will be irrelevant if one animal can land a lethal bite before it comes to grappling; it seems that at this point you actually do acknowledge the relevance of the jaws’ greater reach, albeit only in comparing them to the forelimbs and not to each other.

With the caveat that we are speaking about theropod v theropod matchups, that is a fair assessment.

FWIW, my working assumption is that the meathook claws of the carnosaurs were used to capture and dispatch relatively smaller prey, which (when combined with craniocervical adaptations for macropredation) would have allowed the carnosaurs to attempt to hunt pretty much anything in their environment.

Considering the limited reach of these forelimbs that you pointed out yourself, why would such forelimbs be more advantageous for catching fast-moving, small prey as compared to the jaws (which, as I pointed out, were likely quite nimble and had good range of motion, independent of having to slowly and laboriously turn the entire body)?

Because they were clearly doing something with them, and until a detailed analysis of the sacral anatomy is done, I tend to assume that theropods held themselves more or less horizontally during predation. From that, it follows that the "something" involved prey that only came up to their chests.

Even if we grant "jack knife posture" as a possibility, the torso would need to be held nearly vertically for the claws to be able to come into play before - or even simultaneously with - the jaws.

Additionally, as prey got bigger, the arms got smaller, which says something. I don't know what, but it says something.

I'd want to see functional morphology of the hip joint in large theropods before I form an opinion on this particular point.

What I’ve seen so far is this:

Direct osteological evidence for elevated trunk posture during running comes from the structure of the acetabulum in allosaurids (Molnar and Farlow, 1990), Sinraptor dongi (Currie and Zhao, 1993), Torvosaurus (Galton and Jensen, 1979) and dromaeosaurs (Norell and Makovicky, 1997). In these theropods, and possibly others, the most robust aspect of the joint surface is located not on the dorsal surface of the acetabulum, as would be expected if the long axis of the ilium were held horizontal during running, but more cranially and extends onto the pubic peduncle.

from: Carrier, D.R., Walter, R.M. and Lee, D.V. 2001. Influence of rotational inertia on turning performance of theropod dinosaurs: clues from humans with increased rotational inertia. Journal of Experimental Biology 204 (22): 3917–3926.


I think the issue deserves further study (as I wrote, I did some modelling for the rotational inertia in Plateosaurus as a test of the influence of this factor, what I found was an axial rotational inertia around the COM of 4.85 for the standard, horizontal model, and 3.86 for a semi-erect, raised-tail model, which suggests the benefits from that perspective alone would definitely be noteworthy). I might look further into this question in the future.

If you get the chance to work with any large theropods (Tyrannosaurus, Acrocanthosaurus, etc) with respect to the relevant adaptations of the pelvis, be sure to update us.

[theropod]

Oct 2, 2023 0:19:24 GMT 5 lionclaws said:

In general, cursoriality imposes different constraints on mammalian carnivores than on theropods. Moreover, I would question the degree to which cursoriality influenced the flexibility even of theropod hindlimbs. If tyrannosaurs were primarily adapted for forward-backward movement to the exclusion of more agile and flexible side-to-side movements, we would expect the ratio between anteriposterior and mediolateral femoral "diameter" to be fairly high compared to carnosaurs. This holds for some specimens, but not all, or even most.

All data taken from Campione et al 2014:

Carnotaurus
MACN-CH 894......1.01


Allosaurus
AMNH 680............0.897

Acrocanthosaurus
NCSM 14345........0.866

Giganotosaurus
MUCPv-CH 1........0.873


Albertosaurus
ROM 807...............0.689

Gorgosaurus
CMN 530...............1.29

Tyrannosaurus
BHI 3033...............1.22
MOR 555...............0.826
FMNH PR 2081.....0.637

Well those figures are entirely insufficient to make out a difference between groups. Here’s a simple significance test:
Tukey multiple comparisons of means
   95% family-wise confidence level

Fit: aov(formula = V3 ~ V4, data = f)

$V4
                                     diff        lwr       upr     p adj
Allosauroidea-Abelisauroidea   -0.13133333 -1.0098890 0.7472223 0.8924919
Tyrannosauridae-Abelisauroidea -0.07760000 -0.9110711 0.7558711 0.9563335
Tyrannosauridae-Allosauroidea   0.05373333 -0.5019140 0.6093807 0.9530017
…but that is also entirely to be expected based on the small sample size (1 abelisauroid, 3 allosauroids, 5 tyrannosaurids) and the additional, strong confounding factor of the major preservational effect on this feature, which almost guarantees that you would not see a statistically significant difference in this very limited sample here even if there was one in reality. We can show this with a simple power test in R:

pwr::pwr.t.test(d=1, power=0.9, n=)

    Two-sample t test power calculation

             n = 22.02109
             d = 1
     sig.level = 0.05
         power = 0.9
   alternative = two.sided

NOTE: n is number in *each* group
Here d is cohen’s d, the standardized effect size, in this case 1 standard deviation (which is about 0.2 for the data you cited). Power is the probability of rejecting the null hypothesis (no difference) if it is actually false, and n is sample size, to be estimated. So in order to have a power of 0.9, a 90% chance of rejecting the null (no difference) if it is false, we would need a sample size of 23.
Sample size however is in reality only 3, not 23.

We can also turn this around to estimate the power of the limited sample that we do have:
pwr::pwr.t.test(d=1, power=, n=3)

    Two-sample t test power calculation

             n = 3
             d = 1
     sig.level = 0.05
         power = 0.1587909
   alternative = two.sided

NOTE: n is number in *each* group

So this tells us the probability of recovering a significant difference in the sample with a sample size of 3, if the actual difference is 1 standard deviation, is only about 16%.
An added factor that is problematic at small sample size if taphonomy; The ratio of ML/AP diameter of dinosaur femora tends to have more to do with the degree and plane of compaction these femora experienced than with actual interspecific differences. I’d be happy to show you an extensive dataset of Plateosaurus femora that proves this, including femora of a single individual differing massively in this regard, if you are interested.

So while theoretically I’d agree with the prediction that one might expect proportionately higher anteroposterior diameters for hindlimbs with a more restricted mediolateral range of motion, the effects of this on theropods would require a much larger sample to test. As for the claim that "In general, cursoriality imposes different constraints on mammalian carnivores than on theropods", I would argue that while likely, the nature of these differences remains unsubstantiated.

However, As we are on the subject of lateral hindlimb mobility, it can’t really be denied that at least large carcharodontosaurs (Tyrannotitan, Giganotosaurus and Meraxes) have a more dorsally angled femoral head as compared to similar-sized Tyrannosaurus, which would (and this has been proposed before, even if only on the blog of Andrea Cau so far afaik) enhance their lateral mobility at the hip joint.

As for if a signal might be present in the ML/AP diameter ratios of these groups, that is an interesting line of thought that warrants a more in-depth statistical analysis if I can compile a sufficiently large dataset.

In general, tyrannosaurs seem to have two "clusters," one with AP/ML values above 1.2, and one with AP/ML values below 0.85. Carnosaurs tend to cluster in the 0.85-0.90 range. Carnotaurus (highly cursorial among theropods) had a fairly round femur. Even granting cursoriality for Rex, without the limbs playing a significant role in prey capture (as in mammals) or compromises in agility (which would predict a uniformly high AP/ML diameter for tyrannosaurs), it's not obvious how that would translate to a disadvantage, as the primary disadvantages for mammalian carnivores don't appear to apply.

Greater lateral mobility of the hindlimb in Carcharodontosaurs has been interpreted as an adaptation for improved stability by Cau, which seems quite reasonable to me. As for how this would be an advantage for a multi-ton biped that would be likely to sustain life-threatening injuries if it fell, I believe that doesn’t really require much explanation.
Use of theropod hindlimbs in prey capture has actually been proposed on the basis of paleopathological evidence (Rothschild et al. 2001) and foot morphometrics (Kambic 2008, unpublished M.Sc. thesis)

Rothschild, B.M., Tanke, D.H. and Ford, T.L. 2001. Theropod stress fractures and tendon avulsions as a clue to activity. In: Tanke, D.H. and Carpenter, K. (eds.), Mesozoic Vertebrate Life., 331–336. Indiana University Press, Bloomington.
Kambic, R.E. 2008. Multivariate Analysis of Avian and Non-Avian Theropod Pedal Phalanges.Montana State University, Bozeman, Montana, USA, 90pp.

I am, of course, speaking in broad generalities - as one must when assessing the relative value of "dimensional advantage" vs robusticity of build.

I think that may be a factor in the different outlook we have here; I am not trying to speak in broad generalities, but rather trying to point out that dimensional advantage can be of benefit, just as robusticity can be, but it is not at all a foregone conclusion that one or the other will always be advantageous, or more so than the other.

A longer muscle of equal cross-section with the same mechanical advantage could generate the same force over the same angular range of motion as a shorter muscle with the same cross-section. Only that range of motion will actually be greater dimensionally if both the in- and the outlever are longer (keeping MA the same, but increasing the distance by increasing the power-stroke of the muscle).

This presumes that the ratio between in-lever and fiber length is constant, which it may not be.

Or it may be, there is a correlation between fiber and muscle length, after all (even though it is a weak one, which of course increases uncertainty for any conclusions about extinct animals or animals whose muscle fiber length can only be estimated).

I certainly agree that Tyrannosaurus rex specifically (and, to a lesser degree, tyrannosaurs generally) prioritized strength over flexibility. I'm not as confident about the "equal cross-sectional area" thing, given what I've read (which is, admittedly, probably less than you have).

As I said, this depends on the muscle group. It’s also not really ascertainable with any reasonable degree of confidence.

In general, the biggest difference seems to be the in-lever arm, which is (with the exception of ventroflexion) larger in tyrannosaurs.

I would argue that ventroflexion is the most important direction, as it is the most efficient for using the jaws to cause damage.

Fair points all, but if what we're talking about is the general utility of "compactness" vs the general utility of "dimensional advantage" in a fighter, it seems pretty obvious that dimensional advantage is less of an advantage than it appears to be.

What does it "appear to be"? So far I have rarely, if ever, seen anyone acknowledge that it even exists at all, so I would rather say that it is more of an advantage than it appears to be based on what most people seem to think it is.

If there's a small difference (tyrannosaur vs carnosaur), then there will still be vulnerabilities exposed for the "dimensionally larger" creature if it attempts to access "weak spots" on its opponent. By the time a Giganotosaurus or Carcharodontosaurus has a good chance of landing a bite on a Tyrannosaurus' neck, the whole of its own skull will be exposed to the latter's bite.

If there's a large difference (adzarchid vs pantherine cat), then the "dimensionally larger" animal has too little mass spread out over too large a frame, and will almost certainly crumple like a house of cards when the two animals collide. Is it possible that the long beak could be used as a spear to kill the cat? Sure. But it seems orders of magnitude more likely for the stiff, elongated pterosaur to wind up being outmaneuvered, overpowered, broken, and killed.

I may have expressed myself poorly.

In general, it takes one good bite (however prolonged) for a well-armed carnivore to kill its prey (which may well be larger than it), whereas elephants can stab each other 20+ times before a fatal injury is dealt. 

A lion could bite a hippo or a buffalo a hundred times and not kill it or even deal fatal injuries to it, that’s why it needs to resort to a strangling neck bite after all (incidentally something that is much less of an issue for ziphodont or other animals with cutting dentition). I’m sure if an elephant were to stab another elephant with comparable precision, i.e. right in the heart or the aorta, it would kill much more quickly than that. They don’t because elephants don’t fight each other with that level of killing intent (also refer back to what I previously wrote about the difference between fighting and killing and the appropriate techniques and instincts). Maybe they could if they set their mind to it (although doing it to another elephant would be anatomically difficult without outmaneuvering it first). I’ve certainly seen plenty of reports of elephants fatally stabbing rhinos, or warthogs fatally stabbing lions for that matter.

This is a significant difference.

The significant difference is that it is evolutionarily favoured for a predator to (in most cases) evolve jaw-based weaponery, and to kill by precisely targeting an area that allows it to kill its prey with maximum efficiency, whereas the evolutionary pressures for a herbivore to adopt this killing style (or any "killing style" at all for that matter) are much more relaxed. Take Triceratops. We are of course perfectly well aware that Chasmosaurines used their horns and frills for non-lethal intraspecific combat, likely the vast majority of the time. So of course (as the fossil record proves) chasmosaurines sustained many, many non-lethal injuries from such conflicts. But that is reflecting the context in which horns were used most of the time much more than the ability of a horn to kill when viewed in isolation of behaviour. If we looked at strictly intraspecitic fighting in carnivores, we’d also come to the conclusion that bites are pretty bad at killing, as they won’t kill each other the majority of the time (the theropod face biting record you already brought up proves this). But that a predator will, statistically, kill much more frequently than a herbivore should come as no surprise to anyone.

With that sort of performance, I'm not sure a Triceratops could kill Acrocanthosaurus reliably in a head-to-head, much less T-rex.

Depends on the size of the T. rex and Triceratops in question (a case where I think dimensional advantage is of key importance, btw, it matters a lot if that’s a 10 m T. rex facing down a 9 m Triceratops with 1.5 m horns, or a 12 m T. rex facing down a 6 m Triceratops with 0.8 m horns).

With how lightly built most theropod skulls were, big cats would probably be able to do more than merely puncture the nasal. Bears, it's a different story (at equal weights), but cats? Nasal+maxilla would be a hard ask, but completely breaking the nasal seems within the realm of possibility.

Seems like conjecture to me. Possibly with the exception of Jaguars, I’ve not seen evidence to suggest cats perform particularly impressive feats of crushing large bones. Which teeth would they even do that with? Hyaenas use enlarged premolars for bone-crushing. Tyrannosaurus used incrassate maxillary teeth. But the only teeth cats seem to routinely use in biting living prey seem to actually be the canines, and by their length alone those would limit their ability to bite into a large bone with any of the more posterior teeth, as the canines would necessarily have to contact the bone first (creating a series of puncture wounds, but not necessarily biting through a sizeable bone.

Theropod nasals aren’t thin bones for the most part, and are tightly braced against the maxillae. Biting just the nasal alone (provided this could be accomplished without getting bitten first, of course)? Not sure how realistic that is, let alone break it.

Additionally, as previously pointed out, mammalian predators tend to "bite and hold" rather than "bite and release."

That is not unique to mammalian predators, although it would seem it is generally a sign of animals relying on sustained biting because they are not able to bring down prey using mechanical damage alone. Crocodiles and odontocetes both do this too, and often rely on drowning their prey rather than killing it through actual bite damage (in a way analogous to how cats clamp down on the trachea, although the former two use their jaws for immobilizing much more than cats seem to do.

especially considering, as you mentioned, many theropods were quite used to having their faces bitten (and likely by jaws capable of causing more extensive damage overall than those of your average cat or bear).

Depends on where the bite occurs.

Most theropods had low bite forces for their size, but bladelike teeth capable of causing massive soft tissue damage. The skull doesn't have that much soft tissue.

That slicing teeth with low bite force cannot cause severe injuries to bone regions is a myth easily dispelled by looking at what tiger sharks can do to sea turtles. Besides, the skull holds some very essential soft tissues; not just a lot of facial nerves and blood vessels, but also jaw muscles essential to its functioning.

But that such dangerous injuries would usually be avoided during face-biting is sort of my point, and that even bone-crushing Tyrannosaurus were seemingly able to do it without routinely killing each other in the process demonstrates this point.

Probably not (although that’s not a fair comparison, as its skull, while less nimble than the forelimbs, would be able to cause much more damage in exchange),

It is an entirely fair comparison, as the nimbleness of the paws correlates strongly with the likelihood of it being able to gain control over the theropod before either side can start "causing damage."

Gaining control (unlike, potentially, causing fatal damage with a bite or a horn, for which a single contact can be sufficient) does not come as easily as simply making contact with a single paw. Otherwise lions would be gaining total control over their opponent every time they manage to connect with a paw swipe. Contact with one paw may be used as a starting point to facilitate getting a grappling hold, but so could contact with the jaws potentially facilitate a grappling hold with the forelimbs of a theropod (only that contact with the jaws in itself could be used to either grapple, or cause severe, debilitating injuries without the need for grappling).

Two paws on the cheeks/neck and a bite to the snout strikes me as an effective way to deal with a theropod at weight parity, and a strategy that is fairly typical for both felines and bears.

Yes, but now you are not talking about the nimbleness of one paw any more, you are talking about essentially the carnivoran’s whole front half, which I am fairly sure would in fact be much less nimble than just the head and neck of a theropod, especially considering the carnivoran is quadrupedal, or at least severely restricted in its movement (due to lack of bipedal stability) when not in a quadrupedal posture.

Saying it would be easier for a carnivoran to land a hit with one paw is one thing, saying it would be easier for it to gain a solid grappling hold with both forelimbs as well as, potentially, the jaws is an entirely different thing. Also, what would such a grappling hold even be on? The head? Without getting bitten?
That requires a level of precision in gripping with the forelimbs that I am not sure carnivorans have been demonstrated to possess (heck, I would rate a human’s chances of grappling the head of an attacking theropod without getting bitten in the process very low, let alone a cat’s or bear’s, that would have no prior experience or intellectual understanding of what the situation required it to do). For a cat, I’d think that going for the neck would be much more likely (as that’s where cats go for killing their prey), but that in turn means getting well inside a theropod’s (this doesn’t have to get anachronistic, one group I haven’t seen here yet are Phorusrhacids, and this applies to them as well) strike range, strikes that may well spell the end for a similar-sized carnivoran with a single brief contact.

Looking at the citations, they were using a combination of models. Hartman's was one of them, but they were also looking at Paul (2010), Coria and Currie (2002), amd Persons and Currie (2011a&b).

Yes, I am aware of that. But, while I haven’t asked him, I have a hard time imagining Hartman, being a co-author of that study, would have used a skeletal differing much from his own for the volumetric estimates (the mass estimates in the study also don’t suggest that he did, being just very slightly higher than his original ones, as befits their use of a more superelliptical model–in fact they likely should be higher than they were when considering wider tail based were assumed).

If he thought that looking at Paul (2010, which btw is a popular science book, The Princeton Field Guide to Dinosaurs) suggested changes were needed to his skeletal, then I would expect that said skeletal would reflect them by now, which it does not. As for Persons and Currie 2011, this is a study regarding caudofemoralis size that they used to inform the greater width they assumed for to the tail compared to "traditional" slender-tailed reconstructions. This should have little to no bearing on the relative rotational inertias, as it applies to both of them (and would increase both of their inertias by way of increasing their mass, if applied consistently).

Dorsoflexion? Tyrannosaurs still seem to "stand out" with respect to it, based on the craniocervical dynamics study I posted earlier. 

Snively et al. 2007 didn’t quantify muscle sizes, so a lot of that is interpretation based on what people expect to see. Allosaurus also have large nuchal crests on their supraoccipitals to anchor a powerful dorsiflexive musculature, and, while their neural spines are lower (likely to do more with weight support by means of supraspinous ligaments than with movement) they are also anteroposteriorly longer, i.e. providing a large area for muscle attachment.

As for ventroflexion, they could easily rely on the weight of their own head to deliver downward blows. Muscle is expensive, after all.

By that definition an axe would be considered more nimble than a sword.

In general, I certainly think that Tyrannosaurus would have had a reduced range of motion, but I'm not convinced that it would have been much slower - or at least, slow enough to make a difference.

If it needed to turn its whole body to perform a movement that an allosauroid could perform with just the neck due to its greater range of motion, that would certainly make it much slower, even if moving the neck alone were to achieve the same angular speeds.

Comparing bears to apes does dirt on bears and exaggerates the capabilities of apes.

I don’t want to get drawn into any "which cute little mammals are superior" debate here, nor was my statement intended to imply an ape was an equally capable fighter or killer to a bear at parity. This was intended to make a point about how behaviours that work for one don’t necessarily work for the other–see below example of theropod face biting, not to "do dirt on bears". For the record, I’d prefer to get mauled by a bear to being mauled by a chimp, if only because the former promises a quicker death.

I suspect something similar may be the case with theropod face-biting, which after all is documented to have been non-lethal. It makes sense for the face to be the first thing to target in any sort of confrontation, and in a non-lethal ritualized fight where both animals benefit from reducing the risk of death, they may well keep it at that. But that doesn’t mean biting the face would be the "end goal" if the animals were to fight to kill one another.

Assuming realistic behaviors on the part of both parties (eg, a positive phobia of exposing the neck to a similarly armed opponent), I would presume the face and skull to be the primary available targets in most theropod v theropod matchups. The neck is just too vulnerable to xiphodont dentition for it to be otherwise. 

That is a circular argument. The neck wouldn’t be a target, because it would be too good a target? Of course either animal’s objective would be to somehow maneuver its jaws to the neck (or, less likely perhaps, the trunk behind it), in order to place a killing bite–if the fight was actually intended to kill, that is. But the way different groups of theropods would do this would likely differ quite a bit, if by means of speed and flexibility or brute force.

These would be fights of dynamic maneuver, both in terms of footwork and "neckwork," with footwork generally being more relevant for controlling distance, and neckwork being more relevant for the final strike. Add to this the probable intelligence of large theropods (comparable to/in excess of that of a rhesus macaque)

Not so say that theropods weren’t intelligent, I see no reason to expect that they were not, but I know no paleontologist who takes that study very seriously, let alone that interpretation of it. It bases on a very suspect and arbitrary methodology for determining neuron density, and sort of conveniently ignores the difference between endocast and brain size in a really arbitrary way.

Again, I don't want to get too deep down the Tyrannosaurus rex vs [insert carcharodontosaur] rabbit hole quite yet, but I don't see a 20-30 cm difference in skull length being quite as decisive as you make it out to be.

That goes both ways. It is the same relative difference in length that is responsible for the difference in robusticity.
So if the length difference is insignificant, then the difference in robusticity is too.

Which would be a fair point to make, as I would both are probably, in the end, not all that significant, but that is certainly the opposite of what I commonly see being argued when it comes to such power rankings, esp. comparisons of T. rex vs [insert any other theropod that ever lived here].
People can fill literally gigabytes of discussions with sweeping statements of how T. rex is a jaguar and every other giant theropod is a cheetah by comparison, and how much superior it makes the former. But it is more robust precisely to the same degree that those other theropods are longer at mass parity. If there isn’t a significant difference in dimensions at equal body mass, then there can, by definition, not be a significant difference in robusticity. What perplexes me is the propensity I often see for people to acknowledge one as a major, perhaps even a massive advantage, while ignoring the other completely, when the two things are so fundamentally flipsides of the same coin. In reality, of course one would be a somewhat better grappler, and the other would have a somewhat quicker, more nimble bite and greater reach, factors that mutual payoffs.

Depends on the posture, but clearly any grappling ability will be irrelevant if one animal can land a lethal bite before it comes to grappling; it seems that at this point you actually do acknowledge the relevance of the jaws’ greater reach, albeit only in comparing them to the forelimbs and not to each other.

With the caveat that we are speaking about theropod v theropod matchups, that is a fair assessment.

Well I am well past the point where I can freely admit to like to speak of "matchups", but I must confess a continued interest in examining the preconceptions and opinions people tend to hold in terms of how they generally rate certain groups of animals more highly than others, and, if so, do so quite comprehensively, with fairly little regard for real biological payoffs and costs that come with certain adaptations. And I’m interested in examining the actual quality of the evidence (if any) behind such preconceptions. Preconceptions which of course, neither I nor other paleontologists are free of either.

When it comes to tyrannosaurids, I must say that I do see a lot of evidence and various biases flowing into them being overhyped in various circles when compared to other theropods. If there is something that tyrannosaurids were better at than other theropods, there’s likely a study on it. If the reverse is true, despite sufficient empirical evidence, there likely is not, especially not in a comparative manner (leaving such aspects much more ambiguous to a general audience). If such a study’s findings include evidence for tyrannosaurids being better at some things, but not at others, you can be fairly certain to see only the former widely reported, not the latter. Add to that your run-of-the mill bunch of internet hype that often tends to parrot completely false statements (such as the "twice larger brain" idea I recently debunked from a news-article on the Giganotosaurus vs T. rex thread) and we do get to a certain narrative that gets reinforced and hammered home time and time again in the public view, with little nuance or objectivity.

I am not looking at you here btw, in fact I would say that your viewpoint is more balanced than most.

Because they were clearly doing something with them, and until a detailed analysis of the sacral anatomy is done, I tend to assume that theropods held themselves more or less horizontally during predation. From that, it follows that the "something" involved prey that only came up to their chests.

That would impose a lower limit as well as an upper limit on this size, as the arms couldn’t reach infinitely far down either without altering the posture, and would be very easy to avoid for a small-bodied, agile animal. But I would argue that due to reasons and evidence already mentioned, assuming theropods did not alter their body posture depending on the needs of the situation to improve their locomotory performance and/or to bring their forelimbs to bear on a prey item (e.g. a sauropod) is unparsimonious. Based on this logic, if we only had skeletons of mammalian carnivores we might assume none of them were able to grapple large prey with their forelimbs, because we wouldn’t have evidence that they, as quadrupeds, were able to adapt their body posture to allow the limbs to be used for grappling (objectively speaking much more of a stretch than for a bipedal theropod to do the same).

Even if we grant "jack knife posture" as a possibility, the torso would need to be held nearly vertically for the claws to be able to come into play before - or even simultaneously with - the jaws.

I don’t think that is correct based on body proportions in theropods, but regardless, we are ignoring the possibility of a first contact with the jaws (that perhaps weren’t as suitable for sustained grappling, but in exchange were better able to maneuver into the position for such a first contact) being used as an anchor point to maneuver into a position where the arms could then take over in terms of grappling.

Additionally, as prey got bigger, the arms got smaller, which says something. I don't know what, but it says something.

Citation needed. Extreme forelimb reduction occurs in two lineages of gigantic theropods (let’s arbitrarily define that as 5t+), Carcharodontosaurids and Tyrannosaurids (or three if you insist on including Abelisaurids, though I don’t think we currently have any evidence of gigantic members of that group), but not in others, such as Megaraptorans, Allosaurids, Megalosaurids or Spinosaurids.
While there’s no doubt the lattermost are specialized for relatively small prey, I cannot really detect a convincing signal among the rest (leaving aside uncertainty as to precise prey composition). In fact Allosaurus, an animal about a third the size of Tyrannosaurus (speaking for typical specimens) but with similar-sized humeri and much larger forearms, hands and claws probably hunted prey about the same size as the prey Tyrannosaurus hunted (Stegosaurus and various sauropods, the latter making up the majority of the herbivore biomass in the Morrison formation), at least sometimes.

[Infinity Blade]

Nov 4, 2021 20:36:59 GMT 5 Infinity Blade said:

We need to talk about elephants...

Despite their tusks, these are not the most important assets in elephant fights. In fights between bull elephants, musth trumps body size and tusk possession in agonistic encounters. When neither bull has a musth advantage, then size trumps tusk possession, even if the size advantage is modest. So if you had a tusker going up against a tuskless bull anywhere over 10 cm taller at the shoulder, the tuskless bull wins (Chelliah & Sukumar, 2013). It's for this reason that in Asian elephants, tuskless bulls aren't necessarily inferior in combat to tuskers, as they often are larger (to some extent), have more robust builds, more muscular trunks, and more developed skulls (link).

You would think tusks would reliably overcome a (surely not extreme) size and build advantage, but more often than not they don't. It's only when musth and body size are equal that tusks actually become a decisive factor (because well, what reason is there for it to not win at that point?). The study I linked to above says that tusks are likely only to be used for goring after the opponent has been rendered vulnerable. The fact that fatal goring tends to occur after a wrestling match breaks apart and one elephant exposes itself (link) seems to corroborate this.

Normally I try to avoid posting old accounts to prove a point, but in this case old word on tuskless bulls overpowering tuskers through sheer strength seems consistent with modern observations.

“Strange as it may appear, there are occasional instances where a haing is feared even by powerful tuskers. Mr. C. B. Lacey informed me of one or two cases within his knowledge. Mr. Danson also informed me of a case, and I myself have met with one instance. It is also a generally recognized fact amongst the Burmans. In such cases it will usually be found that the haing is an enormously powerful elephant with an unusually fine development of the trunk; the strength and dexterity in its use when fighting against a tusker is said to compensate fully for the absence of tusks. In Pegu, some years ago, a reliable Burman tracker casually informed me about a fight he witnessed in the jungle between a very large haing and an ordinary sized tusker; though the haing received some nasty wounds, he put the tusker to flight.

Tusks are occasionally snapped during fights. Mr. Danson, of Messrs. Darwood & Co., showed me a piece of a very fine tusk fractured about a foot or so from the point. This piece when found in one of the Shweli forests was covered with congealed blood. Mr. Petley, who knew the facts, informed me that the fight occurred between a good-sized wild tusker and an enormous solitary haing which was well known in the district (Shweli). Several Burmans witnessed the combat, during the course of which the haing snapped off the large portion of tusk referred to.

Emerson Tennent states that Mr. Mercer, Civil Political Officer of Government at Badulla, sent him a jagged fragment of elephant tusk 2 ft. long, weighing between 20 and 30 lbs., which had been brought to him by natives who, being attracted by noise in the jungle, witnessed a fight between a tusker and one without, and saw the latter seize one of the tusks of his antagonist and wrengh from it the portion in question. — [Emerson Tennent, 1859, Vol. II, page 280.) Ceylon elephants are generally tuskless — not one in a hundred is found with tusks. They have tushes 10 ins. to i 2 ins. long and i in. to 2 ins. in diameter. — [Emerson Tennent, page 274.)”

archive.org/stream/elephantstheirdi00evan/elephantstheirdi00evan_djvu.txt

This basically means that, discounting musth, the biggest asset to elephants isn't their tusks. It's their size/strength. No problem if they're going up against something smaller than themselves (and elephants are the biggest animals in their ecosystems). But what happens when they're deprived of that size advantage, and they're pitted against certain extinct giants as big as or bigger than them?

Hell, there have even been instances where tuskless elephants actually mortally wounded/killed tuskers. Here->, for instance, two bulls (one tusked, the other tuskless) fought to the death. While the tuskless bull died, the tusker was also grievously injured and died of its wounds later. If you replaced that tuskless bull with say, an equal sized theropod, that tusker would have been dinner.

So lb for lb, I don't rate elephants as highly as many people would. They're not the worst fighters lb for lb to be sure, but they're really not anything special either. P. namadicus over T. rex? Sure, definitely. A bush elephant over a T. rex? ...Nnnnnnaaaaahhhh...I definitely don't think it deserves to be rated as highly as many have done. Not entirely sure on rating, though.

Wanted to reiterate a bit. To put it another way, elephants basically fight like overgrown antelope. Their tusks serve as holding devices like bovid horns (and I remember posting a study that found that elephant tusks even continue the trend of antelope horns in their thickness to length ratio at their larger sizes) for wrestling. Their trunks can be used to wrestle, and they push their heads/faces against each other. Lots of much smaller ungulates today fight by primarily wrestling, particularly cervids and many bovids.

Like the horns of antelope or the antlers of deer, elephant tusks can indeed be serious goring weapons if applied correctly. But it's not their most common behavior when it comes to combat, it's not their primary means of defending themselves (most cervids and bovids simply run from their predators, while elephants rely on their sheer size to fend off predators and defeat rivals), and it's not a given should a similarly large animal try to attack it. Wrestling and headbutting are more common in elephant fights than actual goring. In fact, elephants rarely actually fight to the death, except in high density populations arising from high population growth in confined areas (link->).

[Supercommunist]

I knew sharks can be forced into tonic immobility but I didn't realize how easy it was to trigger that.

www.reddit.com/r/HardcoreNature/comments/1aniaam/sand_tiger_sharks_attempting_to_mate_only_to_put/

Sharks really do appear to be glass cannons.

[Supercommunist]

I know the crab body plan is a very succesful evolutionarily speaking but does anyone know why they seem to be mediocre fighters? I am sure we have all seen videos of arthropods killing much larger verterbrates, some without veomon.



So why don't we see crabs preform similar feats? The closest thing I can think of was the coconut crab and the booby video, but even then the animals where in the same weight class.