For almost 130 years, the existing theory of dinosaur evolution has gone unchallenged. But a new study published in the journal Nature seeks to shake-up the entire dinosaur family tree. We may soon have to unlearn a lot of things we have learned about dinosaurs over the years. Until now, it was believed that these giants originated in South America on the ancient supercontinent of Gondwana. The new study says they might have originated in the United Kingdom.
United Kingdom was where the first dinosaurs roamed
The first dinosaurs might have originated in the Northern Hemisphere on the ancient supercontinent of Laurasia. It was possibly an area that is the modern day United Kingdom. This is the first reassessment of dinosaur evolution in 130 years. According to the new family tree, the carnivorous beasts like T. rex and Velociraptor had been wrongly classified in the old system.
What led scientists to believe that the United Kingdom, not South America, was the place of origin of the first dinos? The short answer is decades old fossils recovered from Scotland and England. Until recently, paleontologists dismissed them as unimportant. But the new family tree places them near the base of evolution because they were one of the oldest fossils.
First dinosaurs originated 15 million years earlier than thought
Cambridge University paleontologist Matthew Baron, the lead author of the study, said the previous family tree suggested that the first dinosaurs originated about 232 million years ago. After analyzing hundreds of fossil records, Baron concluded that the first dinos appeared 247 million years ago, about 15 million earlier than previously believed. The older classification system was developed in 1888 by Harry Govier Seeley.
Harry Govier Seeley studied the sizes, shapes, and arrangements of bones of different dinosaur species, and their evolution over time. He classified dinos into two main groups based on the structure of their pelvic bones: Ornithischia (bird-hipped group) and Saurischia (reptile-hipped). The bird-hipped creatures included the likes of Stegosaurus, and were herbivores.
Not all bird-hipped dinos were herbivores
The reptile-hipped group was further divided into two branches: carnivores such as T. rex and herbivores such as Brontosaurus. Several generations studied this in schools. To re-evaluate the evolution, Baron and his colleagues studied many more fossils and species, many of which were discovered only a few decades ago. According to the new classification, the meat-eating theropods (including T. rex) belong to the same group as bird-hipped dinos. If accepted, it would suggest that not all bird-hipped giants were herbivores.
Under the new system, the reptile-hipped group still includes Sauropoda. But scientists suggest that the archaic carnivorous group Herrerasauridae also belongs to the reptile-hipped group. Matthew Baron said it came as a shock because it ran counter to everything we’ve been taught. Herrerasauridae was previously linked to theropods. Keeping herrerasaurids and theropods separately in the new tree would mean that their meat-eating traits such as large skulls and sharp teeth evolved independently.
The first dinos walked on two legs
The latest study also claims that the first dinosaurs were small, omnivorous, used grasping hands, and walked on two legs. Baron says the dinos evolved to become meat-eaters on two distinct occasions. Baron’s classification system bears resemblance to ideas proposed by Thomas Huxley in 1870. Huxley believed that birds evolved from carnivorous dinosaurs and placed them with bird-hipped dinos under a group called Ornithoscelida (bird-limbed). At the time, Huxley’s theory was rejected.
Baron said in a statement that he and his team were open to the possibility that their conclusions could be wrong. Fossils records of early dinos are incredibly rare, making it difficult to draw a firm conclusion. Baron said his theory should be reviewed and tested by other biologists.
