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Post by Creodont on Mar 23, 2023 9:17:14 GMT 5
I think a club is better suited to fighting other armored dinosaurs than predators. Why would ankylosaurines evolve a club to kill or repel a theropod when a thagomizer would’ve sufficed? A club makes better sense when fighting an armored opponent. Spikes or horns would fail to penetrate armor or do so sufficiently; many times they’d shatter on impact. In contrast, clubs were ideal for hitting a carapace. They might not cause lethal injury, but that’s not preferred in intraspecific contests.
(BTW I wasn’t sure which subforum this would fit best in)
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Post by Infinity Blade on Mar 23, 2023 16:25:39 GMT 5
Why would a sabertooth evolve giant serrated fangs to kill a horse or a deer when normal cat fangs would’ve sufficed? Evidently this trait was selected for in sabertooths, even in the face of conical-toothed cats that lived in the same ecosystems with them. It just is. The same applies to ankylosaur tail clubs. Just because they might have evolved primarily for intraspecific combat doesn’t mean it’s not just as useful for fighting a hungry predator.
Also, what do you mean “sufficed”? A thagomizer is just as good of an antipredator weapon as a tail club.
Ehh, depends on the species.
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Post by Supercommunist on Mar 23, 2023 19:29:41 GMT 5
Honestly a thagomizer is probably an overall more dangerous weapon than a tail club. I think its optimistic to assume that an ankylosaurus could reliably break similar sized theropods legs with a single blow.
If you have ever seen people fight with baseball bats or other blunt instruments, they don't usually kill or even knock a person out with a single strike to the head.
Horns and other sharp weapons don't always penetrate either but a bad cut on a fleshy area can lead to an infection.
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Post by theropod on Mar 23, 2023 22:14:16 GMT 5
Supercommunist Actually that matches up with the results Arbour (2008) got when doing computational simulations of ankylosaur tail club strikes. Size of these tail clubs varies quite a bit, and has a large impact on the capacity to break bone with a strike. This size variation (and delayed ontogenetic development of the club) itself may also speak against defense being a primary driver in the evolution of these structures, since predation would be expected to be a fairly constant selective pressure and should also result in relatively uniform, optimized morphology (including in young and small individuals that would be in particularly strong need for a defensive weapon). On the other hand, a club primarily driven by intraspecific competition or sexual selection only needs to be large in sexually mature individuals, not juveniles. Arbour actually found that large ankylosaur tail clubs could break bone, but small to mid-sized ones probably couldn’t. However, note that Mallison (2011), when analyzing the tail of Kentrosaurus, noted that Arbour’s assumptions about tail musculature were significantly more conservative than his, so maybe the forces in that study are underestimated. Either way though, there’s certainly still reason to have doubts about how easy it would have been to break large bones with a tail club strike. Creodont There is actually direct evidence supporting your hypothesis. Arbour et al. (2022) analyzed the occurrence of pathologies in the osteoderms of the ankylosaur Zuul and found them to be concentrated in a way that seems most consistent with intraspecific combat. Also what I wrote above. So yes, intraspecific combat seems to be a likely explanation, or primary function at any rate, for ankylosaur tail clubs. That being said any self-respecting animal (especially if it’s as slow as an ankylosaur) with a weapon fit for intraspecific combat would, given the opportunity, also use that weapon to defend itself against a predator. And of course a tail strike doesn’t necessarily have to cause crippling damage to large bones of an attacker in order to be a deterrent. Most likely, there would have been major variation in the power of these strikes, depending on the individual ankylosaur, and also its specific intentions. Maybe some strikes were bone-shatteringly powerful while others were not. Still, any predator would still have incentive to try and avoid such strikes. --- Arbour, V.M. 2009. Estimating Impact Forces of Tail Club Strikes by Ankylosaurid Dinosaurs. PLOS ONE 4 (8): e6738. Arbour, V.M., Zanno, L.E. and Evans, D.C. 2022. Palaeopathological evidence for intraspecific combat in ankylosaurid dinosaurs. Biology Letters 18 (12): 20220404. Mallison, H. 2011. Defense capabilities of Kentrosaurus aethiopicus Hennig, 1915. Palaeontologia Electronica 14 (2): 1–25.
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Post by Creodont on Mar 25, 2023 3:39:18 GMT 5
To be clear, I do think both thagomizers and tail clubs would both have been effective antipredator mechanisms.
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Post by Infinity Blade on Mar 25, 2023 21:17:41 GMT 5
Even if a blow doesn’t straight up break a bone, couldn’t it still cause internal organ damage? They’re not really analogous, but bottlenose dolphins can kill other dolphins with blunt trauma, and it’s not just broken bones they cause. They can cause hemorrhages and organ ruptures too. It’s not inconceivable to me that an ankylosaur tail club, even if it fails to break bone (though it very well could), could still cause internal soft tissue damage.
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Post by theropod on Mar 25, 2023 22:38:12 GMT 5
Even if a blow doesn’t straight up break a bone, couldn’t it still cause internal organ damage? They’re not really analogous, but bottlenose dolphins can kill other dolphins with blunt trauma, and it’s not just broken bones they cause. They can cause hemorrhages and organ ruptures too. It’s not inconceivable to me that an ankylosaur tail club, even if it fails to break bone (though it very well could), could still cause internal soft tissue damage. I think it depends on the soft tissue. Delphinids can kill other large animals through soft tissue damage caused by ramming, but their rams are also powerful enough to break bones (at least that goes for killer whales). If they don’t, I think that’s not so much for lack of power, but rather because they ram relatively soft-bodied targets (like the belly of another delphinid, or a shark) that simply don’t have a bone in the way that would have to break first. Generally speaking my impression is that soft tissues are less susceptible to blunt trauma than bones (if I were given the choice between taking a hit with a club in the stomach or in the head, I would choose the stomach every day; the former would likely break my skull, possibly kill me; the latter if I am unlucky might rupture something and cause internal bleeding, but might also not do much at all because the impact energy might get dispersed too much by the tissue). Of course some internal organs are indeed prone to rupture, but I think for most of them a blunt force strong enough to do so would also be capable of breaking bone. However, to get at the internal organs in a theropod dinosaur, one would need to get past the bones first anyway, because the chest and stomach cavity is pretty much entirely encased in ribs, shoulder girdle and gastralia. Those are fairly thin bones though, and may be much easier to break than a giant leg bone. In which case, of course, the thing to be concerned about might rather be punctures from broken ribs than the impact on the soft tissue itself. However a slight problem I see there for the ankylosaur would be the height advantage a large theropod would have over it. Sure, if within reach I could totally see a hit to the chest having rib-shattering effects, but all ankylosaurs are built quite low to the ground, most aren’t very large either, and I’m not sure they could swing their tails effectively at something that’s 2-3 m off the ground (and if it could, then how much this would reduce the force it could produce). In the legs (i.e. the targets it would have the easiest time swinging at), I suspect the soft tissues would be less at risk of taking severe damage than would be the bones, considering there would mainly be muscles and tendons in there. They could be bruised, sure, maybe there would be some limited bleeding, but I don’t think soft tissues in the limbs would be what would be taking actual dangerous injuries from an ankylosaur if the bones wouldn’t first. |
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Post by Supercommunist on Mar 26, 2023 0:40:27 GMT 5
It's possible but the same applies for spiked weapons. Literature has noted that dingo's rarely inflict very visible tissue damage on one another but if you inspect a dingo that was killed by its kind and peel back its skin you can see all the internal damage their teeth inflicted.
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Post by Infinity Blade on Mar 26, 2023 3:24:16 GMT 5
Hmm, good point. If it's powerful enough to cause internal organ damage or hemorrhaging, it would probably be strong enough to break bone anyway. To be clear, I don't doubt an ankylosaur's ability to damage bone, since even with Arbour's apparently conservative muscle reconstructions, at least large ankylosaur knobs appear capable of it. Heck, even the small ankylosaur clubs in her study were found to have had impact forces comparable to those of Stegosaurus spike. And contrary to what she says, we know a Stegosaurus spike could puncture bone (considering how we literally have two examples of bone penetrated by a spike). Granted a Stegosaurus spike would probably have better luck damaging bone due to the fact that all that force is concentrated on a tiny spike tip, but still.
(Another thing Arbour admits in her study is that she doesn't factor in movement of the body with the hips and hindlimbs, which would definitely add force to the blow. In other words, it's like finding out how hard you or I could punch, but literally all we moved was our arm, not our shoulders, hips, and legs moving in with the punch. Of course, no one trying to throw a serious punch would do this.)
I recently found a study on striped and Risso's dolphins killed by bottlenose dolphins, with injuries including broken bones and internal hemorrhaging and organ ruptures (it's worth noting that dolphins don't just ram, they also tail slap and body slam other animals, and all three would have contributed to the blunt trauma seen in their victims). I can send it to you if you're interested.
I wasn't trying to compare blunt weapons to pointed ones in my post, just noting that a blunt weapon could theoretically do this. You are absolutely correct, though (and I'll have to look that stuff up on dingos).
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Post by Supercommunist on Mar 26, 2023 21:02:23 GMT 5
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