Therizinosaurus’ claws were useless against predators

[Gwangi]

So Prechistoric Planet's climbing Therizinosaurus babies and adult smacking tree branch to knock down Bee hive are now outdated?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

Makes me think of some turtle species, which use their elongated claws in courtship displays. Somewhat ironic since Therizinosaurus was originally thought to be a turtle.

[Carnoking]

So Prechistoric Planet's climbing Therizinosaurus babies and adult smacking tree branch to knock down Bee hive are now outdated?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

Makes me think of some turtle species, which use their elongated claws in courtship displays. Somewhat ironic since Therizinosaurus was originally thought to be a turtle.

Now I'm picturing two therizinosaurus courting that way 

[GojiraGuy1954]

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.

Because they're different animal groups that lived and evaded predation differently? It's like saying Smilodon's saber teeth were evolved for sexual display because pantherines exist and can kill things without having sabers

[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.

Because they're different animal groups that lived and evaded predation differently? It's like saying Smilodon's saber teeth were evolved for sexual display because pantherines exist and can kill things without having sabers

Nope, it's really not. Machairodont canines are not comparable to ankylosaurid clubs. Apples and bratwurst. And for the umpteenth time, Arbour and her colleagues openly acknowledge that the clubs were indeed suitable for defence against predators whenever the need arose. They state that very clearly in the abstract of their paper:

Ankylosaurid dinosaurs were heavily armoured herbivores with tails modified into club-like weapons. These tail clubs have widely been considered defensive adaptations wielded against predatory theropod dinosaurs. Here we argue instead that ankylosaurid tail clubs were sexually selected structures used primarily for intraspecific combat. We found pathological osteoderms (armour plates) in the holotype specimen of Zuul crurivastator, which are localized to the flanks in the hip region rather than distributed randomly across the body, consistent with injuries inflicted by lateral tail-swinging and ritualized combat. We failed to find convincing evidence for predation as a key selective pressure in the evolution of the tail club. High variation in tail club size through time, and delayed ontogenetic growth of the tail club further support the sexual selection hypothesis. There is little doubt that the tail club could have been used in defence when needed, but our results suggest that sexual selection drove the evolution of this impressive weapon. This changes the prevailing view of ankylosaurs, suggesting they were behaviorally complex animals that likely engaged in ritualized combat for social dominance as in other ornithischian dinosaurs and mammals.

https://royalsocietypublishing.org/doi/full/10.1098/rsbl.2022.0404

But if you or anyone else still chooses to consider themselves a better authority on ankylosaurids than Arbour and Zanno and Evans, then that is your prerogative. This is my last post on the topic.

[Gwangi]

I think it is important to look around at extant animals and their outlandish features to get an idea of what prehistoric animals likely used theirs for. Things like the long turtle claws I mentioned, peacock feathers, deer antlers, antelope horns, narwhal tusks. Various crests, horns, and other adornments on lizards, insects, and birds. Bright, flashy colors. They're almost all primarily for sexual display and intraspecific combat. Yes, it hurts a wolf to get poked by deer antlers. But that is not what antlers evolved to do. Evidenced by the fact that only males generally grow them and they fall off every year. The defensive capabilities that any of these features might have is just an added bonus. Although the players have changed over time, the game has stayed the same.

[Kapitaenosavrvs]

Oh wow. That is quite interesting and also cute. Something new to me. Thanks for bringing it up in this context here. And in general

I never really thought of weapons when thinking of Therizinosaurus i have to say. Not in the first Place. I can greatly agree with what Gwangi said above me.

[Faelrin]

@Gwangi Thanks for sharing that red eared slider mating dance footage. It's adorable. Granted I never really thought to look up this sort of thing to begin with, but glad to have seen it now, especially with how familiar I am otherwise with these turtles. I suppose that also helps to approach this subject matter in a different way.

I was honestly pretty initially skeptical about this right off the bat. Thinking more about this though, and reading some of the material shared in this thread has got me to be more open to this.

Hopefully some day we can find additional specimens to help shed more light on this intriguing animal as well. Least we got lucky with Deinocheirus anyways.

[Gwangi]

@Gwangi Thanks for sharing that red eared slider mating dance footage. It's adorable. Granted I never really thought to look up this sort of thing to begin with, but glad to have seen it now, especially with how familiar I am otherwise with these turtles. I suppose that also helps to approach this subject matter in a different way.

I was honestly pretty initially skeptical about this right off the bat. Thinking more about this though, and reading some of the material shared in this thread has got me to be more open to this.

Hopefully some day we can find additional specimens to help shed more light on this intriguing animal as well. Least we got lucky with Deinocheirus anyways.

You're welcome. I have a red-eared slider and he used to do that display at his reflection in the aquarium glass. I haven't seen him do it in a long time, but he's also 30 years old. Maybe his libido isn't what it used to be.

[Faelrin]

@Gwangi Congrats on having him for that long. Dude's nearly as old as me.

[Gwangi]

@Gwangi Congrats on having him for that long. Dude's nearly as old as me.

He's probably older than that actually. I got him 31 years ago and he was already an adult.

[Sim]

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.

Earlier ceratopsoid members have horns that would have worked well in defense or combat within their own species, so I think it's not clear they originally evolved for display, even though it is possible.
It isn't clear Triceratops used its horns in defense against predators, as Mark Witton expressed in this blog post which casts doubt on horn use for defence, there is no way to know why Tyrannosaurus bit the horn of a Triceratops: http://markwitton-com.blogspot.com/

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.

Stegosaur plates would have helped in defense from predators by blocking access to more vital body parts.  Regarding what came first, it's believed to be the spines as some stegosaurian plates have a thickened central portion suggesting they are modified spines.

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.

I doubt keeping its claws inwards is something Therizinosaurus did if its claws were as fragile as this paper suggests, as the claws could have been broken if pushed into the Therizinosaurus with force such as in drawing them away from an attacking predator or having them pushed inwards by a predator.

[Cretaceous Crab]

Earlier ceratopsoid members have horns that would have worked well in defense or combat within their own species, so I think it's not clear they originally evolved for display, even though it is possible.

It isn't clear Triceratops used its horns in defense against predators, as Mark Witton expressed in this blog post which casts doubt on horn use for defence, there is no way to know why Tyrannosaurus bit the horn of a Triceratops.

I agree. However, if one were to employ the theory of Occams Razor, the most plausible scenario is that the Tyrannosaurus was in some form of direct conflict with the Triceratops, and bit at the horn because it was the closest part of the Triceratops anatomy to its jaws. Whether the Tyrannosaurus was biting in an act of predation, defense or intimidation, is unknown.

[andrewsaurus rex]

I believe T. rex bit Triceratops' horn to help immobilize the head.  It would prevent Triceratops from both running away and from slashing/stabbing with its dangerous horns.  This would allow a second T.rex to attack the Triceratops, probably at the rear legs, and bring it down.  Purely speculative on my part but it follows a method used by  modern day large predators, like lions and it would explain why T. rex would bite the horns.....it wasn't because they were tasty, I don't think.

[Pliosaurking]

Didn't the horn heal somewhat afterwards? On The Truth about killer dinosaurs this was stated. Now whether or not the Tyrannosaurus was hunting it is unknown, but they did have an head on encounter and the Triceratops either got away or overcame the Tyrannosaurus. If I were to guess I would say the Tyrannosaurus was attempting predation.

[OwossoHarpist]

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

Well years ago, Jack Horner did a TV documentary which claims that the Ceratopsian horns and thick heads of Pachycephalosaurs were only used to displays, while blatantly ignoring the ceratopsian skulls that shows lots of injuries from rival and predatory battles.

Seriously, It's all rubbish! Why would anyone say that they're all only for displays when these features are clearly shown to be defensive weapons against predators and rivals? Are they that highly sensitive to animal violence or something and are like "ugh" every time they see a lion killing a gazelle on TV?