Therizinosaurus’ claws were useless against predators

[GojiraGuy1954]

I don't recall anyone claiming that ankylosaur clubs and stegosaur spikes and ceratopsian horns were only used for display. Whoever said that? Citation?

All of those have been stated before just not recently

[suspsy]

I don't recall anyone claiming that ankylosaur clubs and stegosaur spikes and ceratopsian horns were only used for display. Whoever said that? Citation?

All of those have been stated before just not recently

No, as I already explained before, they really haven't. The notion that ceratopsian horns evolved primarily for sexual selection and ankylosaurid tails evolved primarily for intraspecific conflict does not mean that they were only for those purposes. I don't know why so many people think such appendages can only serve a single purpose, but it's incorrect. The authors of the studies will happily state the same.

[andrewsaurus rex]

I agree totally suspsy, and that's been my point all along.  But for a while now I have been reading about studies that claim features, like ceratopsian horns and ankylosaur tails evolved PRIMARILY for display.  There have been numerous other examples (eg pachycephalosaur heads) of dinosaur features that seem to have an obvious purpose  being claimed in someone's paper to actually have evolved for display.  It's the default conclusion these days.  And now, apparently, therizinosaur hand claws too.  This  seems to be a fad in the past few years, just like in the 80's and 90's it was fad like to claim dinosaurs were ever bigger, faster, stronger and more terrible.

Even IF the primary reason for therizinosaur claws evolving so large was for display, and I remain skeptical, does that mean they couldn't have been used for other purposes as well, such as defense?....according to you (and me) no.  The long claws must have been practically useful in some way, otherwise they were really in the way of day to day life and I can't imagine they would have evolved, in preference to other simpler display features.

But maybe it's true.  Maybe virtually all exaggerated features on animals originally evolved for display.  To impress the opposite sex, for example.  Sexual selection is certainly a powerful evolutionary force.  Or maybe simply species recognition, in cases where both males and females of a species share the same exaggerated feature..  And maybe animals learned over time that their features could be used for other things, like out competing a rival male for the ladies, or defending yourself from a  T. rex or a lion...

[suspsy]

Honest question: did you actually read the therizinosaur study? They address your question right in the discussion.

And no, it's not a fad, it's simply paleontologists doing more and more research and steadily gaining a better, clearer understanding of how these dinosaurs evolved and why they evolved certain features in the first place. 

[EmperorDinobot]

But but but it was in Jurassic World Dominion and don't they have a paleontologist as a consultant?!


Just kidding, I can imagine it may have been traumatic for one of them to lose a claw while doing xyz.

[stargatedalek]

So, just going to dissect a few elements here.

Ceratopsian horns originally evolved for display, not for defence, and not for intraspecific combat. This is not a fad, a vague idea, or people trying to push against the norm, it's observable trends throughout the group as a whole and in particular among earlier members. The vast majority of ceratopsians have horns or bosses that are blunt, round, placed in impractical locations, or that even curve inward towards their own heads.

Over time various individual ceratopsian species independently developed horns that would have been more practical for intraspecific combat, and in a few cases, such as Triceratops, for defence from predators. Whether that need or behaviour directly influenced the development of their horn shapes or whether the coincidental changes to their horn shapes then enabled those behaviours is unclear. What is clear is that Triceratops in particular definitely used its horns for defence from predators.

No one that I can think of has ever suggested ankylosaur armour and tail clubs were for anything but defence from predators. I haven't heard it talked about much so I can't speak for its credibility but a recent paper even covered what they cited as evidence ankylosaur armour was built to shatter and form painful splinters for an attacker when bitten into, and could be regrown. Early members of the group with less or no armour tend to feature spines and similar features designed to make them difficult to bite or swallow. While these were likely also used for recognition and display towards predators (need more aposematic ankylosaurs please!), their primary function was defensive.

I don't think there has been serious suggestion stegosaur plates were used for defence since the 70s. Intimidating or aposematic displays towards predators is certainly possible, but they serve no practical function in protecting the animal. This is likely why many stegosaurs rely on spines in addition to their plates in order to defend themselves. As for which came first (and therefore which is a modified version of the other), decorative plates or defensive spines, I don't know, I'm not certain we have enough early members to be particularly conclusive there.

Therizinosaurus is in something of the exact opposite position to Triceratops. Its ancestors show evidence for their claws having utilitarian function in feeding, but Therizinosaurus itself specifically has lost the ability to use its claws in feeding or defence. The claws of Therizinosaurus are so fragile, so long and thin, that even using them to pull branches would have likely caused serious damage.

I get it, my initial reaction was also trepidation. I thought "ok so it didn't slash but maybe it jabbed with them instead?", and nope, these stress tests covered that too. Therizinosaurus claws were fundamentally incapable of serving either a practical defensive function or for use in feeding from branches. They could have been plenty intimidating, with bright colours or dramatic patterns, and Therizinosaurus could have moved them about in intimidating ways, but no way was it slashing Tarbosaurus across the face or even jabbing for vitals, it's claws would shatter down to the bones.

Please consult the diagram from this paper:

Spoiler

[close]

But, why would Therizinosaurus have lost the functional uses of its claws? I would posit the obvious difference between it and other relatives is the habitat; Therizinosaurus lived alongside Deinocheirus in a wetland environment. We also don't have a published skull, if the claws were no longer being used for feeding, it stands to reason the skull/beak likely was instead. This makes sense as an adaptation to feeding in a wetland as opposed to a woodland environment.

[Lynx]

So, just going to dissect a few elements here.

Ceratopsian horns originally evolved for display, not for defence, and not for intraspecific combat. This is not a fad, a vague idea, or people trying to push against the norm, it's observable trends throughout the group as a whole and in particular among earlier members...

I won't quote the entire thing as I don't wish to flood, but that read was very interesting!
 I learned quite a few new things, especially about Ceratopsians.

I'm well aware the information wasn't directed towards me, but nonetheless, thank you for the info!

[Fembrogon]

But, why would Therizinosaurus have lost the functional uses of its claws? I would posit the obvious difference between it and other relatives is the habitat; Therizinosaurus lived alongside Deinocheirus in a wetland environment. We also don't have a published skull, if the claws were no longer being used for feeding, it stands to reason the skull/beak likely was instead. This makes sense as an adaptation to feeding in a wetland as opposed to a woodland environment.

This suggestion in particular intrigues me; suddenly I wonder if we have another big, weird theropod with the potential to turn out even weirder than anyone already expected, depending on if we can find more substantial remains in the future.

[GojiraGuy1954]

Please consult the diagram from this paper:

Spoiler

[close]

It doesn't seem like they accounted for possible keratin sheathing when they did their stress tests unless i'm missing something

[andrewsaurus rex]

interesting post stargatedalek, thanks.  One thing I would say about ankylosaurs is that I've read it suggested many times that the primary purpose of ankylosaur tail clubs was for intraspecific combat, rather than defense.  I don't agree with that conclusion but I was under the impression it was the prevailing belief these days.

Therizinosaurus' long claws seem such a strange evolution.  And I can't imagine what selective pressures would have caused those long, apparently  fragile claws to be beneficial to the animal.  They would seem to make its  hands nearly useless, as the animal would have  to be very careful for fear of breaking its claws.  Strange to have such long, strong arms which are more or less unusable for anything except waving them around provocatively or in a threatening manner.  And if for intimidation, surely predators would quickly learn that those hand claws posed no threat to them...

[stargatedalek]

interesting post stargatedalek, thanks.  One thing I would say about ankylosaurs is that I've read it suggested many times that the primary purpose of ankylosaur tail clubs was for intraspecific combat, rather than defense.  I don't agree with that conclusion but I was under the impression it was the prevailing belief these days.

Therizinosaurus' long claws seem such a strange evolution.  And I can't imagine what selective pressures would have caused those long, apparently  fragile claws to be beneficial to the animal.  They would seem to make its  hands nearly useless, as the animal would have  to be very careful for fear of breaking its claws.  Strange to have such long, strong arms which are more or less unusable for anything except waving them around provocatively or in a threatening manner.  And if for intimidation, surely predators would quickly learn that those hand claws posed no threat to them...

The same could be said for Tyrannosaur arms, why get so small and become less practical? Simple, the animal wasn't using them for traditional utility.

Perhaps it was large enough that even though using the claws aggressively would have caused serious injury, the threat of mutually assured death by bleeding out or infection kept predators at bay. Or perhaps it had a particularly vicious beak to defend itself with. Maybe it even stood in deep water and used the claws to create space between itself and a would be predator, tiring it out until the predator gave up. There are plenty of ways a large animal can defend itself without slashing or stabbing with its hands.

If we want to get really speculative, maybe Therizinosaurus even batted/boxed at would be threats with its arms, while keeping its claws pointed inwards. Or even used its arms to drag threats underwater and hold them there like kangaroos.

[Carnoking]

I actually think it's a really interesting idea that those massive claws would have been used for some form of sexual display, and makes me wonder what the courting rituals would look like with them involved.

That said, I do have a hard time believing that those claws wouldn't be brought to bear if a Therizinosaurus found itself in a pinch with a predator. Whether that be through a threat display or a panicked swipe, who's to say, but I imagine even the most vain Therizinosaurus would sacrifice a massive claw or two to escape a brash Tarbosaurus with its life.

[GojiraGuy1954]

interesting post stargatedalek, thanks.  One thing I would say about ankylosaurs is that I've read it suggested many times that the primary purpose of ankylosaur tail clubs was for intraspecific combat, rather than defense.  I don't agree with that conclusion but I was under the impression it was the prevailing belief these days.

Therizinosaurus' long claws seem such a strange evolution.  And I can't imagine what selective pressures would have caused those long, apparently  fragile claws to be beneficial to the animal.  They would seem to make its  hands nearly useless, as the animal would have  to be very careful for fear of breaking its claws.  Strange to have such long, strong arms which are more or less unusable for anything except waving them around provocatively or in a threatening manner.  And if for intimidation, surely predators would quickly learn that those hand claws posed no threat to them...

If we want to get really speculative, maybe Therizinosaurus even batted/boxed at would be threats with its arms, while keeping its claws pointed inwards. Or even used its arms to drag threats underwater and hold them there like kangaroos.

If it supposedly can't even manipulate thin branches with the claws without them being damaged how would it be able to hold down a struggling multi-ton predator with no issue

[stargatedalek]

interesting post stargatedalek, thanks.  One thing I would say about ankylosaurs is that I've read it suggested many times that the primary purpose of ankylosaur tail clubs was for intraspecific combat, rather than defense.  I don't agree with that conclusion but I was under the impression it was the prevailing belief these days.

Therizinosaurus' long claws seem such a strange evolution.  And I can't imagine what selective pressures would have caused those long, apparently  fragile claws to be beneficial to the animal.  They would seem to make its  hands nearly useless, as the animal would have  to be very careful for fear of breaking its claws.  Strange to have such long, strong arms which are more or less unusable for anything except waving them around provocatively or in a threatening manner.  And if for intimidation, surely predators would quickly learn that those hand claws posed no threat to them...

If we want to get really speculative, maybe Therizinosaurus even batted/boxed at would be threats with its arms, while keeping its claws pointed inwards. Or even used its arms to drag threats underwater and hold them there like kangaroos.

If it supposedly can't even manipulate thin branches with the claws without them being damaged how would it be able to hold down a struggling multi-ton predator with no issue

Elbow hook? Or just swinging the massive arms like battering rams while keeping the claws pointed safely inwards.

[suspsy]

Victoria Arbour herself raised a very salient point in an article that was shared earlier: if ankylosaurid clubs really did evolve primarily as defensive weapons against tyrannosaurs, then how were nodosaurids able to survive all the way up to the end of the Cretaceous without any such clubs? Denversaurus, anyone?



The most reasonable explanation is that ankylosaurid tails didn't evolve primarily as defensive weapons, same as how elephant tusks, rhino horns, and hippo teeth didn't evolve primarily as defensive weapons either. I don't get why some people are so upset by that revelation. I've even seen comments on social media saying that ankylosaurs have been "ruined." That's just plain preposterous, no two ways about it. As Arbour and I myself have pointed out, it doesn't mean that all those appendages couldn't still be used against predators.

[bmathison1972]

yeah, it's like saying if you use your fingers for typing, you can't pick your nose!     

[Fembrogon]

I guess it's just far too easy for people to assume that one proposal automatically disproves the other - if it's X, it can't possibly be Y - rather than taking the time to extrapolate from the ideas more thoughtfully. Not a big surprise, really.

[DragonRider02]

So Prechistoric Planet's climbing Therizinosaurus babies and adult smacking tree branch to knock down Bee hive are now outdated?

Could the claws work as effective feather grooming tools? Maybe Therizinosaurus couples bonded by scratching/grooming one another.

[andrewsaurus rex]

this has become a very interesting thread, beyond the revelations about Therizinosaurus.  With regard to ankylosaurs and nodosaurs, the same could be said for various lineages of ceratopsians.  Some had horns that were useful for defense, as stargatedalek mentioned, and others didn't.  But all survived in the face of predators, no doubt by employing strategies other than going toe to toe with the predator.. 

But in most cases, it seems, what appear to be weapons dinosaurs evolved for defense actually evolved initially for mating purposes  (either through species recognition, alluring display or intraspecific mating combat) and some species were also able to put them to good use defensively as well.  And, the ones that were lucky enough to develop features that were also useful in defense against predators may well have had a better chance of being more successful lineages, due to their enhanced defensive capabilities.

So where do stegosaurs fit into all this then?  Were their spikes initially developed for defense, like super duper porcupine quills, or did they initially evolve for mating purposes of some kind?

[Over9K]

If you were a predator, would you test this theory with healthy adults? I think I'd focus on the young, the old, the weak, the sick and the slow anyway, making their "weapons" less effective from the get-go.

Too often in paleoart, we are shown predators preying upon vital, healthy adult prey species.