RECUR - New for 2024

[stargatedalek]

Well regardless of it being a carnivore/omnivore it doesn't seem all that reasonable to base the head of therizinosaurus off deinocheirus. Therizinosaurs are maniraptorans and are much more derived than ornithomimosaurs, so that would be like putting a tapejarid head on an azhdarchid; related and reasonably close, but definitely wrong.
Not to mention that other therizinosaurs skulls exist and are quite different from deinocheirus.

Do we have gut content from Therizinosaurus to prove it wasn't an omnivore? Regardless, Deinocheirus and Therizinosaurus cohabited the same areas, and so were likely feeding on the same plants in a similar way. Would it most likely have been this similar? No, but the idea that it's skull would (more broadly) resemble those of herbivores that feed on aquatic plants is a perfectly reasonable reconstruction.

We know from strength studies that Therizinosaurus claws were not functional for feeding, unlike those of other Therizinosaurs. So it was eating primarily using its skull, not its forelimbs, therefore the skull would not realistically be all that similar to the skulls of the forelimb feeding species. Let alone much smaller ones.

[Sim]

Firstly, we have no evidence that Deinocheirus ate plants, as far as I'm aware.  Secondly, therizinosaurids lack features for feeding on aquatic plants e.g. by being more upright than other theropods.  There is nothing to suggest Therizinosaurus fed on aquatic plants rather than on the trees and other plants that were widespread in its environment.  Its claws being unable to pull food towards it doesn't stop Therizinosaurus from simply feeding on trees and other plants with just its head.

[crazy8wizard]

Firstly, we have no evidence that Deinocheirus ate plants, as far as I'm aware.

None directly, but the skull shape and a paper using finite element analysis suggests that it would have likely eaten softer foods, so the aquatic plant hypothesis comes from that. It isn't as set in stone as gut contents, but without any teeth to study, that's the best we may get.

[crazy8wizard]

Also I recall seeing a hypothesis that Therizinosaurus might not be bringing food to its mouth from its hands, but using the giant claws and hands to pull food towards the mouth and using the neck and mouth to feed, somewhat like a sauropod. Try to imagine pulling a bar towards you by just flexing your elbows.

[thomasw100]

I would argue that Therizionosaurus and Dinocheirus have been placed into two very different clades based on a considerable number of skeletal characters which are quite distinct. If we look at the differences and similarities of skulls of dinosaurs of other clades in general, they tend to be comparatively similar for genera within a clade. So it would be not reasonable to assume that a Therizinosaurus would have had a Deinocheirus like head.

[crazy8wizard]

I would argue that Therizionosaurus and Dinocheirus have been placed into two very different clades based on a considerable number of skeletal characters which are quite distinct. If we look at the differences and similarities of skulls of dinosaurs of other clades in general, they tend to be comparatively similar for genera within a clade. So it would be not reasonable to assume that a Therizinosaurus would have had a Deinocheirus like head.

Not to mention how really distinct skeletal features like this usually come from niche partitioning. Pretty dissimilar aside from really big coelurosaurs with huge arms.

[stargatedalek]

Firstly, we have no evidence that Deinocheirus ate plants, as far as I'm aware.  Secondly, therizinosaurids lack features for feeding on aquatic plants e.g. by being more upright than other theropods.  There is nothing to suggest Therizinosaurus fed on aquatic plants rather than on the trees and other plants that were widespread in its environment.  Its claws being unable to pull food towards it doesn't stop Therizinosaurus from simply feeding on trees and other plants with just its head.

Fair enough, though I still posit that the skull would likely not resemble the smaller, hand feeding relatives particularly closely regardless or whether or not it resembled Deinocheirus. If for example it resembled those of large browsing hadrosaurs, it would still look more like Deinocheirus than the typical Segnosaurus/Erlikosaurus based skulls Therizinosaurus is often given.

As for whether Deinocheirus ate plants, if it didn't, than it's beak coincidentally resembled a shape common for herbivores. Thus they may have coincidentally looked similar anyway.

[Sim]

I was just thinking now that in terms of ecology, Therizinosaurus was probably more like the contemporary Saurolophus than Deinocheirus...

[Faelrin]

I think the current consensus for Deinocheirus is that it was an omnivore based on the evidence and understanding of it at hand (a mix of an herbivore and a piscivore). Its stomach preserved over 1000 gastroliths alongside fish remains (2014 paper is paywalled so I'm not sure what extant the material is, other then wikipedia saying it consists of scales and vertebrae).

Both the 2014 paper with the description of the new material, a 2017 paper (paywalled), and a 2019 paper alludes to it having features of an herbivore. A 2022 paper further supports Deinocheirus being an omnivore.