The first dinosaurs may have originated in the Northern Hemisphere, probably in an area that is now Britain. This is one of the results of the first detailed re-evaluation of the relationships between dinosaurs for 130 years. It shows that the actual theory of how dinosaurs evolved and where they came from may well be wrong. This major shake-up of dinosaur theory is published in this weeks’ edition of the journal Nature. The evaluation shows that the meat-eating beasts, such as Velociraptor and Tyrannosaurus rex, have been wrongly classified in the dinosaur family tree. One of the conclusion is that dinosaurs first emerged 15 million years earlier than previously believed.
According to the new study’s lead author, Matthew Baron of Cambridge University, the fossil evidence recommends that this origin may have occurred further north than current thinking suggests – possibly in an area that is now the UK. He said, “The northern continents certainly played a huge role in dinosaur evolution than we previously thought and dinosaurs may have originated in the UK.” The previous version of the dinosaur family tree was developed 130 years ago by Harry Govier Seeley, a paleontologist also working at Kings College, London.
By comparing the arrangements, shape and size of fossilized bones of different species of dinosaurs and how they changed over time, he devised a theory of how they evolved and how they were related He concluded that there were two main groups of dinosaurs: those whose hip bones were more reptile-like, which he named Saurischia and those whose hip bones were like those of modern-day birds, which Seeley called Ornithischia. The bird-hipped group were all exclusively plant-eaters and included familiar creatures such as Triceratops and Stegosaurus. The lizard-hipped group had two branches: the meat-eaters, such as T. rex and the plant-eaters, such as Brontosaurus.
The reason that the Northern Hemisphere, and particularly the UK, has become more likely to be the place for the emergence of the first dinosaurs is the fact that two crucial fossils were found in England and Scotland. For decades they were dismissed as unimportant species, but following the redrawing of the dinosaur tree, they are now placed close to its base. The English and Scottish finds suggest that it is now more likely that the first dinosaurs emerged 245 million years ago in the northern part of the planet on a landmass called Laurasia, rather than 230 million years ago on a more southerly unit called Gondwana. The results came as a “shock”, said Matthew Baron.
The researchers involved cautioned, though, that the fossil record for early dinosaurs is so scattered that it would be difficult to make any firm claims at this stage for their origins. But the team hopes that its findings will spur paleontologists to search for more fossil evidence to back up the new ideas. A question to one of the main theories of dinosaur evolution is bound to be controversial.