Teyuwasu-Seriously (Wrong) Speculative Saurischian

Update 2020! – Now blatantly inaccurate! New research on the bones of "Teyuwasu" has interpreted them as simply belonging to the contemporary herrerasaurid Staurikosaurus, the "robustness" of the bones actually being due to calcium replacement and expansion ("chunkification" in the words of one palaeontologist), a common occurrence in the Santa Maria Formation.

Nonetheless, the image and text below will remain up as a testament to the time when "Teyuwasu" was still a possible animal, a record of how science marches on in palaeontology and how some fossils can be seriously misinterpreted. Plus the concept of a herbivorous basal saurischian is kinda cool anyway.



Teyuwasu barbarenai ("Big lizard"*) is a poorly known saurischian from the Late Triassic of Brazil that's really only definitively known from a femur and a tibia, with a few other broken and scrappy pieces that may belong to this animal. This seems like a recipe for a dubious, indeterminate taxon that lacks any key defining traits to set it apart from all the other basal Triassic saurischians.

Teyuwasu, however, has one rather conspicuous feature that sets it apart from all the others: its leg bones are seriously robust. Lengthwise, they are similar in size and proportion to each other as those of Eoraptor, yet they're almost twice as thick. Basal saurischians are well known for having slender legs, so what was Teyuwasu doing with big chunky legs like that?

I took this as an opportunity to reconstruct Teyuwasu as a carnivore-turned-herbivore, along the same lines as therizinosaurs, Chilesaurus and other herbivorous theropods, hence the larger gut than is typical of basal saurischians, and the enlarged first toe for bearing weight (a recurring trait in herbivorous theropods). Such a herbivorous diet allows for the opportunity to sequester carotenoids from plant material, providing it with a fetching red patch around the eyes.

A far-fetched piece of speculation for such a poorly represented taxon, but where would the fun be in just drawing a chunky Eoraptor? In the absence of proper data, speculate wildly, and all that.

This reconstruction was done for A Dinosaur A Day, and is one of several I'm donating as a volunteer whilst the usual artists take a well deserved break. While they're gone, we're providing art for all the crap dubious and fragmentary theropods (or near-theropods in this case) that have been missed out on so far. Lucky us. One down, three more to go from me!

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*Although this is the official etymology, Teyuwasu is a grammatically incorrect combination of the root words. "Teju Guasu" and even "Teyu Guazu" would be acceptable, but as is the rules of nomenclature we're stuck with Teyuwasu.