The carnivorous dinosaurs who turned vegetarian

The great lineage of dinosaur carnivores, the theropods, also produced its share of herbivores writes Dr Dave Hone The diet of an animal is strongly linked to a great deal of anatomy, behaviour and physiology and even evolution. As a result, diet is one of the key pieces of information that palaeontologists will seek to determine of a new find in order to learn about the animal and how it fitted into an ancient ecosystem. Naturally the jaws and teeth tend to be a bit of a giveaway, but there may be other clues in the body such as the presence of gastroliths (stomach stones) that would have acted like the grit in the crop of some modern birds and helped an animal to break up tough plant food.The non-avian dinosaurs had three major lineages, the first two of which: sauropodomorphs (mostly long-necked giants like Diplodocus) and the ornithischians (all kinds of odds and sods including Stegosaurus and Triceratops), were exclusively herbivorous. The final group were the theropods that include animals like Tyrannosaurus and Velociraptor (and include the ancestors of birds) and were primarily carnivorous, but not exclusively so. In addition to the birds, which obviously include a great number of seed eaters and other herbivorous forms, several different lineages of theropod turned away from the path of munching on fellow animals and moved into plant eating.In a broad sense (e.g. carnivore vs herbivore vs omnivore) the diet of an animal is generally a close match for its close relati...
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