To kids, there are only two kinds of dinosaurs: meat-eaters and plant-eaters. But to paleontologists, those are just diet distinctions. Paleontologists divide dinos into two different groups based largely on pelvic structure: reptile-hipped saurischians, and bird-hipped ornithischians.
Those two categories are called 'clades', and they're fundamental to the study of dinosaurs. But a new study is casting doubt on those two groups, as well as moving the infamous Tyrannosaurus Rex to a new spot on the dinosaur family tree.
The study, by Matthew G. Baron, David B. Norman & Paul M. Barrett, was published in the journal Nature. If the findings in this study are accepted by paleontologists, then it will upset our understanding of the family tree that was first established in [Victorian times](http://
Universe Today