Herrerasaurus skeleton replica at a special exhibition of the Naturmuseum Senckenberg (Wiki Commons / Eva K)
Smithsonian Magazine has an interesting piece about carnivorous dinosaurs. The evolution of large meat eating dinosaurs is a long and complicated story. Dinosaurs evolved around 235 million years ago. At that time, they were lanky and small. One of the largest early meat eaters was Herrerasaursus. It was about 16 feet long and lived in Argentina during the Triassic. Paleontologists have been searching for clues as to how and when the larger dinosaurs evolved.
Up until now, paleontologists thought theropods remained generally small and on the ecological sidelines from about 235 through 201 million years ago. It was only after a mass extinction at the end of the Triassic, at the 201 million-year mark, that carnivorous dinosaurs started to get big. But that view is starting to change thanks to a new reading of the bone trail by scientists who think large meat-eaters may have appeared much earlier.
Virginia Tech paleontologist Christopher Griffin says a key player in this story is Herrerasaurus. This early dinosaur roamed Triassic Argentina about 230 million years ago and reached more than 16 feet in length with a mass greater than a polar bear. There is some debate about whether or not Herrerasaurus is truly a theropod, but it was a carnivorous dinosaur and was one of the largest of its time.
The known carnivorous dinosaurs during the later part of the Triassic appeared to be smaller and less imposing than the crocodile relatives they lived alongside (such as Postosuchus from the southwestern United States). Thanks to a better understanding of dinosaur growth, however, paleontologists have found that some of those little theropods were hiding a secret.
