And: More challenges to dino-to-bird dogma

by Jonathan Sarfati and Lita Cosner

T. Rex and Velociraptor were ‘hypercarnivorous’ predators; part of the sub-order Theropoda.1 Dinosaur documentaries and movies like Jurassic Park routinely feature realistic-looking depictions of them ripping other dinosaurs limb from limb, even swallowing newly-hatched dinosaurs whole. There is some good evidence for this: the turkey-sized Compsognathus was found with a lizard in its belly;2 there is a famous fossil of Velociraptor locked in mortal combat with a Protoceratops, and a T. rex coprolite (fossil dung) was found with a “high proportion (30–50%) of bone fragments”3 (see also T. rex drops clue).

Vegetarian theropods

However, the discovery of Nothronychus graffami, one of the therizinosaur branch, suggested that at least this branch of theropods ate plants.4 And a new study,5 by the same lead author, Dr Lindsay Zanno of the Chicago Field Museum, suggests that even in the theropod suborder, usually considered the carnivorous dinosaurs, they were more the exception than the rule. 6 Out of 90 ‘species’ of theropods she and her colleague Peter Makovicky analyzed (a likely-inflated number), 44 of them showed clear signs of vegetarianism: “the ornithomimosaurs, therizinosaurs, oviraptorosaurs, alvarezauroids, several early birds [sic], and the single troodontid Jinfengopteryx.”7

When trying to deduce the diet of an animal that has been fossilized, normally the bones and teeth are all that remains. So a scientist might think that a certain animal was a carnivore based on its sharp teeth and claws that would be good at ripping flesh. But those same teeth and claws would also be good at processing rough vegetation. In the case of the theropods, there was a small amount of fossilized dung and stomach contents that allowed scientists to analyze the actual diet of the dinosaurs. Imagine their surprise when members of this ‘hypercarnivorous’ family turned out to have salad5 as a regular part of their diet! This made more sense of the peg-like—or even absent—teeth in some of these theropods…..

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