When I was a kid I used to make little wooden models of dinosaurs. My favourites were my T.rex, triceratops and a pteranodon that hung from the ceiling amongst my Spitfires and Tornados. Even at that age I knew that the three main groups of dinosaurs that existed were the ornithischians (these would be your triceratops, stegasaurus, dinosaurs with horns), the sauropodomorphs (these are the long necked beasts like diplodocus) and the theropods (T.rex, velociraptor, not to mention all modern birds).
The ornithischians formed a clade of their own with their bird-like hips and the sauropodomorphs and theropods grouped together to form the lizard hipped saurischians. It had been that way for well over a hundred years and nothing was likely to change that. But then something changed that.
An open access paper published in Nature last week is, potentially, going to turn the world of dinosaur classification on its head. The paper is based on the PhD of Cambridge University student Matthew Baron. In it he looked at 457 characteristics from 74 species of dinosaur. He then used this enormous data set, by far the biggest of its kind, to rebuild the family tree of dinosaurs without basing it on any preconceived dogma. He let the data tell its own story.
The results threw up several interesting ideas as well as the new classification. He deduced that the whole dinosauria family evolved 437 million years ago, some 5-15 million years earlier than previously thought. Also, that they originated from the northern Laurasia continent, not the southern Gondwana.
By far the most shocking result, however, is the regrouping of the theropods. There is some circumstantial evidence to back up the claim, though. It always bugged me that the ornithischians were not the dinosaurs that went on to become birds, even though they had bird like hips. It is the theropods that became our feathered friends of today. With the theropods moved over to join the ornithischians in the newly coined ornithicelada grouping then that becomes much more satisfying.
It also implies that feathers were a much more ubiquitous evolutionary outcome than previously thought. We’ve known for a while that basically every theropod had feathers, yes, even T.rex, and many but not all ornithischians did too. With the new grouping it suggests that perhaps every dinosaur initially had feathers of some kind and that the sauropods lost them somewhere along the way.
As I often write here, it is important to remember that one paper is never proof of anything. This data needs to be looked at independently, reanalysed and reproduced. Like all good hypotheses it makes several predictions that can be tested in the real world. There will be plenty of paleontologists out there looking for ways to shoot this theory down. A few years from now we will probably have a feeling for how well this new hypothesis has stood up to scrutiny. Personally, I like it; it feels right. Luckily, me and my silly feelings will have no say in determining its veracity, the experts will decide that.