Study sheds light on the evolution of the earliest dinosaurs
The classic dinosaur family tree has two subdivisions of early dinosaurs at its base: the Ornithischians, or bird-hipped dinosaurs, which include the later Triceratops and Stegosaurus; and the Saurischians, or lizard-hipped dinosaurs, such as Brontosaurus and Tyrannosaurus. In 2017, however, this classical view of dinosaur evolution was thrown into question with evidence that perhaps the lizard-hipped dinosaurs evolved first — a finding that dramatically rearranged the first major branches of the dinosaur family tree. Now an MIT geochronologist, along with paleontologists from Argentina and Brazil, has found evidence to support the classical view of dinosaur evolution. The team’s findings are published today in the journal Scientific Reports. The team reanalyzed fossils of Pisanosaurus, a small bipedal dinosaur that is thought to be the earliest preserved Ornithiscian in the fossil record. The researchers determined that the bird-hipped herbivore dates back to 229 million years ago, which is also around the time that the earliest...