Tyrannosaurus rex versus Spinosaurus aegyptiacus

[creature386]

Dec 10, 2013 2:42:43 GMT 5 Godzillasaurus said:

Their teeth were still somewhat resistant to side forces, however, as their conical shape would need to be adept at withstanding immense pressure from the prey that it caught.

The paper theropod mentioned said that there was a strong correlation between predator size and prey type in spinosaurid. This means smaller ones were piscivores, while larger ones ate fish and prey animals considerably smaller than themselves.
Here the quotes:

Biomechanical data support known feeding ecology for both African slender-snouted crocodile and alligator, and suggest that the spinosaurs were not obligate piscivores with diet being determined by individual animal size. [Â…] Spinosaurus represents one of the biggest, if not the biggest theropod dinosaur [58], yet scaled to the size of an alligator, gharial or slender-snouted crocodilian, it performs poorly, especially in resistance to torsion. For a taxon such as Spinosaurus, the ability to feed on larger, struggling prey was not conferred by the possession of a snout that was relatively well equipped to deal with associated feeding loads, but may have been achieved by simple size-related advantages.

www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0065295
If this holds true, Spinosaurus won't have commonly experienced 'immense' pressure. That doesn't mean it never hunted large prey, but probably not frequently enough to develop adaptations.

[Godzillasaurus]

The paper theropod mentioned said that there was a strong correlation between predator size and prey type in spinosaurid. This means smaller ones were piscivores, while larger ones ate fish and prey animals considerably smaller than themselves.

I am not sure what of my claims you are correcting, but 1. mature spinosaurus' were generalist piscivores, meaning that large fish made up more of their diet yet smaller terrestrial animals would have also been inclusive and 2. not once did I say that spinosaurus would have hunted large dinosaurs (in relation to its size), but rather small to medium-sized dinosaurs, most specifically animals like ouranosaurus

If this holds true, Spinosaurus won't have commonly experienced 'immense' pressure. That doesn't mean it never hunted large prey, but probably not frequently enough to develop adaptations.

A primarily piscivorous animal would surely experience a good deal of lateral pressure when it hunted relatively large animals; even more so than carcharodontosaurus possibly. A diet consisting of such large and powerful fish in conjunction with a snout morphology that is particularly robustly-constructed (in addition with reasonable width and depth, for resistance purposes most seemingly in gripping events), slender (for reducing drag), lack of an exceptional bite force (and killing/crushing morphologies), and pointed conical teeth. All of these features suggest a killing style mostly around gripping large and powerful fish. Spinosaurus lacked the exceptional depth that we see in allosaur rostra or the width that we see in tyrannoaurid rostra; it possessed decent width and depth, which is more-so an implication for balanced multidirectional resistance most logically for gripping large fish. That in conjunction with a rather high snout robusticity (general density) seems to be a particular adaptation for gripping. So no, spinosaurus likely experienced a very good deal of pressure when hunting.

Spinosaurus represents one of the biggest, if not the biggest theropod dinosaur [58], yet scaled to the size of an alligator, gharial or slender-snouted crocodilian, it performs poorly, especially in resistance to torsion

If I am well aware of the definition of torsion, then I would like to state the fact that resistance as a whole is not an issue for spinosaurus, for the reasons that I have already stated. In fact, both vertical and lateral forces would not be as great of a problem as the paper makes them out to be (come on now, they were still strong and robust! I don't care what the paper says, spinosaurus was not weak!). That being said, spinosaurus did not have exceptionally powerful jaws, yet they were still morphologically strong enough to deal with the stress in piscivory.

For a taxon such as Spinosaurus, the ability to feed on larger, struggling prey was not conferred by the possession of a snout that was relatively well equipped to deal with associated feeding loads, but may have been achieved by simple size-related advantages.

The main thing to remember here is the fact that spinosaurus was, fundamentally, a piscivore. As an overview of the subject, let's go back to square one; its jaws were very thin as an adaptation for snatching quick aquatic prey (most specifically, large-bodied fish) from the water with as little drag as possible. Yet, they were also very strong, capable of withstanding and coping with the forces attributed to these fish (in gripping of course). This fundamentally means that resistance is not as big of an issue with spinosaurids as many claim (even the paper is guilty of this).

Its teeth were also well-adapted for piscivory: they were pointed, conical, and completely lacked any sort of serrations. But they were also very robust as well for the same reasons why spinosaurus' jaws were particularly dense and sturdy, much more reminiscent of spikes than needles (as seen in the Indian gharial). It was not designed for killing large terrestrial animals, but they were still inclusive to its diet. This meant that its teeth were not designed for creating fatal puncture wounds (although theropod convinced me that it is still possible that spinosaurus killed this way), despite their perfect stabbing morphology (gripping = piercing in this case).

Spinosaurus was well adapted for killing large fish and resisting gripping stress; that's nonsense to believe that it was not and was only restricted to smaller animals. By comparison to carcharodontosaurus, its snout was much better designed for gripping resistance without fracturing or being injured; the more heavily-constructed morphology of its snout allows this. In turn, the possession of a much less pneumatic rostrum laterally supports the idea that it had a generally more robust and dense snout (Its more impressive rostral density and overall build seems to correspond heavily with its diet of large fish, as it allows for greater resistance) that was more capable of gripping resistance, as it would fundamentally allow its snout to not get broken as easily. I guess what I am trying to say is that the possession of a comparably more heavily-constructed and generally denser rostrum that is not defined by exceptional proportions seems to be a far better implication for gripping resistance than an animal like carcharodontosaurus, as such a morphology would allow spinosaurus to effectively grip large and powerful animals without injury; that is simply the bottom line here, even though spinosaurus' rostrum was still not 100% a solid structure it was just simply more-so than carcharodontosaurus or tyrannosaurus given its denser morphology.

[theropod]

Dec 10, 2013 2:23:23 GMT 5 creature386 said:

Dec 10, 2013 2:13:37 GMT 5 theropod said:

I'm not basing this on some superficial resemblance, it's what Cuff & Rayfield stated based on a FE analysis.
That doesn't mean I claim Gavialis gangeticus to be the best analogy for Spinosaurus, since I'm not entirely sure of the relevance of their results, that based on mere anterior rostral fragments (that of Spinosaurus being less robust than MNSN V4047), just that the skull is not as exceptionally powerful as you claim.
That it could handle the stresses induced by crocodile-like feeding habits seems to be quite a stretch.

This is a bit off topic, but if they used MSNM V4047 as a basis for reconstructing an even more fragmentary specimen, won't it be better to directly use MSNM V4047 for their study or am I getting something wrong?

I agree, that would have made more sense since MSNM is much more complete.
I think the only reason they used that small and gracile rostrum was because it was housed at the NHMUK, so they had easy acess to it for scanning.

[theropod]

The spinosaurus does not have to rip the flesh itself; its conical teeth and vice-like grip would hold a prey animal in place and they would try to get away and could potentially rip the flesh themselves.

It´s rather unlikely any of its prey items had the power to pull free from its grip, inflicting fatal injuries on themselves in the process.

There jaws were still very powerful and dense, so resistance as a whole is, again, probably not going to be a problem here.

Yes it is. If Spinosaurus was built to kill anything of a reasonable size this way, It´s jaws would look more like T. rex´ or crocodilian jaws. Of course it could dispatch a small ornithopod or mid-sized fish by simply biting into it and breaking all its bones by shaking it a bit (On the other hand, the puncture wounds from the bite would be deadly anyway, so why impose such unnecessary stresses on its jaws?), but it´s jaws and teeth simply are totally unsuited for performing this killing style if the victim was large and offered some resistance. The way it´s teeth and jaws developed is not in accordance with such claims, it would make no sence to develope such long teeth, and such a narrow and shallow skull.

Their jaws being thin is one story, but their jaws being strong is an entirely different subject.

No. Despite the obvious difference, there´s natural limit to how strong a skull can be for a given depth and width. And the study I gave you demo0nstrates it did not have a very strong skull.

We know that their teeth would also need to be capable to withstanding large amounts of lateral pressure too, as teeth designed for puncturing and gripping powerful animals would require it, regardless of robusticity (which spinosaurine teeth had, but not exceptionally).

What you are talking about IS robusticity.

This time I was not talking about skull density, but rather the adaptation (or lack thereof) for for such thin jaws to rip flesh when they do not have a good grip on a prey animal. But still, spinosaurus having a good grip on the neck of a prey animal could definitely end in ripped musculature, as the conical teeth would then allow for ripping and tearing to commence. As of now, fatal impalations to the spinal cord do seem much morel likely and effective (for spinosaurus at least), but ripping should still not stay out of the question completely.

Not completely, but it would rather be an accidental by-product of the bite than something it actively tried to cause-otherwise we´d see adaptions towards it, not against it.

Their teeth were still somewhat resistant to side forces, however, as their conical shape would need to be adept at withstanding immense pressure from the prey that it caught.

Undoubtedly their teeth were pretty resistant to side forces, that´s the very reason they are conical (along with preventing the teeth from simply tearing through what it bit, which would be disadvantageous for gripping).

[Godzillasaurus]

It´s rather unlikely any of its prey items had the power to pull free from its grip, inflicting fatal injuries on themselves in the process.

So you are now talking about spinosaurus having powerful jaws that no prey can escape from? And later you talk about their jaws being weak? Obviously animals would have a very tough time escaping from its jaws due to its conical teeth and vice-like grip, but you are being a little hypocritical. It is downright possible that, if not for direct force-related tactics, this could be an efficient (albeit very unusual and odd) way to tear flesh. Note that its teeth would not actually be doing any real tearing- they are for holding flesh in place; instead the force in the event would be causing the clamped area to come apart from the actual body. This is most likely how spinosaurus would have tore flesh off with its jaws (if it ever did so), as its teeth were neither designed for actual killing or cutting but instead deep penetration into an animal's hide and retaining a strong grasp on said prey item.

Yes it is. If Spinosaurus was built to kill anything of a reasonable size this way, It´s jaws would look more like T. rex´ or crocodilian jaws. Of course it could dispatch a small ornithopod or mid-sized fish by simply biting into it and breaking all its bones by shaking it a bit (On the other hand, the puncture wounds from the bite would be deadly anyway, so why impose such unnecessary stresses on its jaws?), but it´s jaws and teeth simply are totally unsuited for performing this killing style if the victim was large and offered some resistance. The way it´s teeth and jaws developed is not in accordance with such claims, it would make no sence to develope such long teeth, and such a narrow and shallow skull.

That is where I feel the mere idea of spinosaurus having thin jaws interferes a bit. Not all crocodilians have wide jaws, yet they are still more than capable of killing larger animals. They have conical teeth too, designed for gripping as opposed to causing fatal wounds. Now, I am completely aware of the fact that (according to you anyway) crocodilians are horrible analogies for spinosaurus, but you still need to realize that there are still morphological similarities between them.

Spinosaurus probably did not hunt and kill LARGE prey (talking large relative to its size), but rather small-medium sized dinosaurs. Small dinosaurs would be no problem for spinosaurus  to dispatch easily, as its jaws and teeth are not only powerful, but they would be able to easily dispatch them. Yes, its jaws were thin and its teeth were conical and unserrated, but that does not mean that spinosaurus could not kill dinosaurs. The same thing goes for the false gharial and slender-snouted crocodile; how do you suppose they tear apart larger prey items, even when their jaws and teeth are clearly designed for piscivory? It would simply have much less problem killing larger animals than the paper implies and certainly much less problem killing animals aside from fish. Of course, this relies on size, but its resistance to lateral force, I feel, is being way underestimated in the paper. 

No. Despite the obvious difference, there´s natural limit to how strong a skull can be for a given depth and width. And the study I gave you demo0nstrates it did not have a very strong skull.

Compared to tyrannosaurids, there is obviously no hope in hell that spinosaurids had more powerful jaws. It it just the fact that their jaws were dense and powerful that sort of "makes up" for their lack of width or depth. I am not implying in any way that spinosaurus was the most powerful theropod, but I feel the resistance ability of their jaws is begin underestimated, as it would be a horrible adaptation for spinosaurus to have had weak jaws, considering its main food source. The study also says that spinosaurus was actually very resistant to vertical stress, but not lateral stress (which is debatable).

For the study, were they using width or length for parity? At length parity, spinosaurus would have a much thicker and more robust skull than the Indian gharial, so there is no reason to believe that it had proportionally weaker jaws in that regard.

[creature386]

Dec 10, 2013 3:17:45 GMT 5 Godzillasaurus said:

The paper theropod mentioned said that there was a strong correlation between predator size and prey type in spinosaurid. This means smaller ones were piscivores, while larger ones ate fish and prey animals considerably smaller than themselves.

I am not sure what of my claims you are correcting, but 1. mature spinosaurus' were generalist piscivores, meaning that fish made up more of their diet yet smaller terrestrial animals would have also been inclusive and 2. not once did I say that spinosaurus would have hunted large dinosaurs (in relation to its size), but rather small to medium-sized dinosaurs, most specifically animals like ouranosaurus

This was just for introducing my point.

Dec 10, 2013 3:17:45 GMT 5 Godzillasaurus said:

If this holds true, Spinosaurus won't have commonly experienced 'immense' pressure. That doesn't mean it never hunted large prey, but probably not frequently enough to develop adaptations.

A primarily piscivorous animal would surely experience a good deal of lateral pressure when it hunted relatively large animals.

I am aware of that, but I guess the paper would have mentioned if it had adaptations for the occasionally taken large prey.

Dec 10, 2013 3:17:45 GMT 5 Godzillasaurus said:

For a taxon such as Spinosaurus, the ability to feed on larger, struggling prey was not conferred by the possession of a snout that was relatively well equipped to deal with associated feeding loads, but may have been achieved by simple size-related advantages.

This is also relevant for the false gharial, which will sometimes hunt and kill monkeys and even decently-sized deer on occasion.

The statement wasn't based on visual comparisons, rather on their FE analysis results. But I agree that the paper has it's flaws, because they used a more gracile Spinosaurus specimen (now after theropod has told me the reason why they used it, I'm convinced that it wasn't the best choice).

Dec 10, 2013 3:17:45 GMT 5 Godzillasaurus said:

Edit: Well I just read some of the paperÂ… And I really do not know what to say about besides the fact that it does not once reference skull density at all. In fact, the mere idea that spinosaurids were weakly-adapted for resisting lateral forces seems very incomplete, as their jaws were not only very dense, but hunting large animals too requires very powerful jaws that, especially in this case, the predator would need to be particularly well-adapted for taking down; having such weak jaws laterally is a horrible adaptation for hunting such large and powerful fish, so I feel that more evidence needs to be brought up on that subject. Also, the long and conical shape of their teeth is not an adaptation for being resistant to vertical pressure, but rather spinosaurid piscivorous nature contradictory to what the paper says.

Maybe that's because Spinosaurus skull density was never studied. Or maybe the paper more focused at the resistance results themselves than the conclusions. Drawing conclusions from the skull resistance maybe isn't a good idea, because there is a quite constant relationship between mass and bite force within crocodila, despite different skull shapes.

[Godzillasaurus]

Quote: I am aware of that, but I guess the paper would have mentioned if it had adaptations for the occasionally taken large prey.

Spinosaurids were not designed for taking down large prey; that is the problem. It was obviously big and powerful enough (as in skull strength) to do so, despite its piscivorous morphology. It had very thin and specialized jaws, but it was still more than capable of killing large terrestrial animals. I feel that is the main problem with the paper, it does not address whether or not spinosaurus had weak jaws in general (which it did not) or compared to other theropods. Compared to tyrannosaurus or carcharodontosaurus, it is a no-brainer. But in general, it was clearly capable of killing large game. And even then, large fish that made up most of its diet would still excrete a good deal of stress on the theropod's jaws. It is just not logical to believe that spinosaurus as a whole had weak jaws that were awful in the realm of resistance considering its piscivorous morphology and nature. If it was an active killer of large terrestrial animals, then resistant jaws would be a necessity.

Quote: The statement wasn't based in visual comparison, but rather FE analysis results

Interestingly, the paper never really mentioned if they were using parity as in length of width parity. Both the Indian gharial and the African slender-snouted crocodile possess very gracile jaws (with the latter animal being more generalized), so I found the idea that spinosaurus was comparatively weaker than both to be odd. Not only is it entirely evident that its jaws were more robust than those of the two crocodilians (as in both wider and deeper at the snout), but it's diet was probably less restricted to fish than even mecistops, and its dentition was also much less gracile in build than any modern piscivorous crocodilians (at least absolutely)

If they were using width parity, then so be it. But at length parity, spinosaurus would seemingly have a considerably wider snout (definitely a deeper snout) than both of those animals, which is why it seems particularly odd to me that it would be weaker to lateral forces. But if they were using a more gracile specimen, then there you have it.

[theropod]

So you are now talking about spinosaurus having powerful jaws that no prey can escape from? And later you talk about their jaws being weak?

No, I'm talking about it having moderately strong jaws but teeth that are very good at gripping.

Since pulling free would mean moving perpendicular to the direction of the tooth-crowns, which are quite long and absolutely not sharp, This would be pretty unlikely. Apart from that a killing style that relies on the prey's own power to work seems a little odd, doesn't it?

That is where I feel the mere idea of spinosaurus having thin jaws interferes a bit. Not all crocodilians have wide jaws, yet they are still more than capable of killing larger animals.

They have conical teeth too, designed for gripping as opposed to causing fatal wounds.

Spinosaurs and Crocodilians have different dental and cranial morphologies. Their teeth aren't any more alike than crocodile teeth and cat canines.

Now, I am completely aware of the fact that (according to you anyway) crocodilians are horrible analogies for spinosaurus, but you still need to realize that there are still morphological similarities between them.

I do, which doesn't mean they apply here.

Spinosaurus probably did not hunt and kill LARGE prey (talking relative to its size), but rather small-medium sized dinosaurs. Small dinosaurs would be no problem for spinosaurus  to dispatch easily, as its jaws and teeth are not only powerful, but they would be able to easily dispatch.

Yes, they could do that with a puncturing bite too. But I'm talking about Ouranosaurus or Aegyptosaurus' size class here.

Yes, its jaws were thin and its teeth were conical and unserrated, but that does not mean that spinosaurus could not kill dinosaurs.

I'm not the one to suggest it couldn't. I merely suggest it didn't do it the same way as crocodiles, because it's morphology doesn't make much sense then.
The following quote is yours, not mine:
"Spinosaurus probably did not hunt and kill LARGE prey"
I'm not the hypocrite here.

The same thing goes for the false gharial and slender-snouted crocodile; how do you suppose they tear apart larger prey items, even when their jaws and teeth are clearly designed for piscivory?

They don't have the same teeth (they are definitely shorter, reducing their surface area perpendicular to their long axis), they have the capability to use torsional feeding, and they can simply drown their prey.

Spinosaurus was far more adept at killing larger animals than these two species due to its much more robust jaws and dentition (and also size)

Spinosaurus rostrum turned out weaker than a slender-snouted crocodile's...
We are talking about relative size, not absolute size.
And I am not arguing Spinosaurus could not kill larger animals, merely THAT IT DID NOT DO IT LIKE A CROC WOULD, which you even agreed with by now.

; it would simply have much less problem killing larger animals than the paper implies and certainly much less problem killing animals aside from fish. Of course, this relies on size, but its resistance to lateral force, I feel, is being way underestimated in the paper. 

The paper uses a digital modeling approach and physics simulation, it is objective.

Compared to tyrannosaurids or carcharodontosaurids, there is obviously no hope in hell that spinosaurids had more powerful jaws. It it just the fact that their jaws were dense and powerful that sort of "makes up" for their lack of width or depth. I am not implying in any way that spinosaurus was the most powerful theropod, but I feel the resistance ability of their jaws is begin underestimated, as it would be a horrible adaptation for spinosaurus to have had weak jaws, considering its main food source. The study also says that spinosaurus was actually very resistant to vertical stress, but not lateral stress (which is debatable).

I'm not arguing Spinosaurus had weak jaws. I just argue they were not monstrusly strong, not enough to kill by application of massive, brute force. I'm not suggesting a carnosaur would be able to use lateral shaking to dismember something either, despite its likely significantly stronger skull that was more adapted for macrophagy.

Spinosaurus did not need to use such killing strategies since it has tools that are absolutely sufficient to use a more unspectacular but less risky method.

The study also says that spinosaurus was actually very resistant to
vertical stress, but not lateral stress (which is debatable).

This is much more consistent with a perpendicular bite, or even a bite with (reduced mandibular involvement had it a different tooth design), where the force is primarily vertical.

For the study, were they using width or length for parity? At length parity, spinosaurus would have a much thicker and more robust skull than the Indian gharial, so there is no reason to believe that it had proportionally weaker jaws in that regard.

The comparison was at lenght parity.
I'm not saying this was the ideal approach for comparison, but the point still remains that Spinosaurus did not have a particularly strong skull.
Not weak or unsuited for fighting, but definitely no argument for suggesting it regularly imposed extreme (as in "Tyrannosaurus rex extreme, perhaps more") lateral and torsional loads on it (which it would have to in order to rip things apart for killing them).

[Godzillasaurus]

Spinosaurs and Crocodilians have different dental and cranial morphologies. Their teeth aren't any more alike than crocodile teeth and cat canines.

If spinosaurus was designed for killing more than anything, we would most likely expect its rostrum to be generally deeper and less dense overall. The density attributed to its rostrum was advantageous for gripping resistance; that is the bottom line. Its snout was designed to withstand pressures in gripping WITHOUT INJURY; which is instead the opposite case in many theropods designed for killing like allosaurus.

Their teeth ARE, in fact, quite similar in build: they are conical and robust, only well designed for piercing and gripping.

I'm not arguing Spinosaurus had weak jaws. I just argue they were not monstrusly strong, not enough to kill by application of massive, brute force. I'm not suggesting a carnosaur would be able to use lateral shaking to dismember something either, despite its likely significantly stronger skull that was more adapted for macrophagy.

Carnosaurs most likely did not have very strong snouts in terms of gripping ability; as their gracile and sparse build would likely lead to stress fracturing more-so than in spinosaurus. They were characterized by very deep rostra (which is an obvious anatomical feature used for vertical and forceful killing), but they were not particularly robust as evidenced by the fact that they were very pneumatic and not very dense unlike the rostrum of spinosaurus. Spinosaurus possessed a generally far more robust rostrum that was much denser in build (evident in its less pneumatic design; this can be seen laterally and ventrally, even though it is not a 100% solid structure of course. It was simply much more of a solid piece) and, despite lacking in the same dimensions, was most likely less prone to bending and fracturing possible in gripping. Spinosaurus was well designed for gripping large fish, carcharodontosaurus was designed to kill vertically without nearly as much reliance on gripping.

This is much more consistent with a perpendicular bite, or even a bite with (reduced mandibular involvement had it a different tooth design), where the force is primarily vertical.

And then you still must note that they incidentally tested only the MOST GRACILE PORTION OF SPINOSAURUS' ROSTRUM. The full resistance of spinosaurus' snout was simply never tested properly, as they did not account for the more broadened, deepened, and still very dense central part of its rostrum. Naturally, this area would have had much higher resistance capabilities than the reasonably more gracile and specialized premaxilla due to its increased dimensions.

I'm not saying this was the ideal approach for comparison, but the point still remains that Spinosaurus did not have a particularly strong skull.

Oh, but it did...

[Runic]

Dec 11, 2013 2:37:18 GMT 5 Godzillasaurus said:

Well I don't feel like talking about this anymore. It has nothing to do with you, but it is just disinteresting me.

lol welcome to the club.

[Godzillasaurus]

Dec 11, 2013 2:46:34 GMT 5 Runic said:

Dec 11, 2013 2:37:18 GMT 5 Godzillasaurus said:

Well I don't feel like talking about this anymore. It has nothing to do with you, but it is just disinteresting me.

lol welcome to the club.

Indeed...

[Carcharodon]

Spinosaurus wins, it has a large size advantage that's too much to overcome.

[thesporerex]

Dec 17, 2013 3:01:17 GMT 5 Carcharodon said:

Spinosaurus wins, it has a large size advantage that's too much to overcome.

I agree(this topic was the shit back in the day but it so boring now, but at least it has more of an interesting topic than lion vs tiger)

[dinokid202]

i think trex wins simply because it had a much stronger bite force. but spinosaurus was still bigger though

[Carcharodon]

T.rex does have that large bite force, but it doesn't have a gape large enough to get a good grip anywhere on spinosaurus (except for the neck, which would be out of its reach and it would put itself in danger if it tried to get to the neck)