Compiled by Hikmet Geckil
For more than a century, the placement of dinosaurs on the branches of their family tree has been based on the shape of their hips.
In 1888, Harry Seeley, a paleontologist, said that all dinosaurs could be places into two categories: bidr-hipped (Ornithischia) and lizard-hipped (Saurischia). Since then, the premise has been widely accepted.
This classification has now been radically challenged by proponents of a new tree which, if accepted, swaps large subfamilies around, sheds new light on dinosaurs’ evolution and suggests they may have originated not in South America, as widely assumed, but perhaps in some Northern Hemisphere locality such as Scotland.
Researchers from the University of Cambridge and Natural History Museum in London analyzed the skeletons of 75 different dinosaur species, collecting 35,000 data points about 457 physical traits. What they found is that the theropods (a group that eventually gave rise to modern birds) are in the wrong group. Based on their analysis these creatures should be moved in with the ornithischians and this new bunch could be renamed Ornithoscelida. Study shows that Tyrannosaurus and its relatives may be on the wrong side of the tree.
CreditBaron et al./Nature
The new tree implies that dinosaurs emerged some 247 million years ago, a little earlier than previous estimates, and that their origin may not have been in South America, where several very early dinosaurs have been found.
The findings, published in the journal Nature, hint that dinosaurs may have originated in the northern hemisphere rather than the southern, and could upend an understanding of dinosaur evolution that has gone largely unchallenged for some 130 years.
The dinosaur family tree is traditionally divided into ‘bird-hipped’ (Ornithischia) and ‘lizard-hipped’ (Saurischia) lineages, with an early group of carnivorous dinosaurs, Herrerasauridae, branching off at various places in the family tree. Under the newly proposed regime, theropods such as T. rex are now grouped with bird-hipped dinosaurs such as Stegosaurus.
Knowing things that happened million years ago is quite a challenge. So, we might still wait for more data and confirmation. How dinosaurs gone extinct also is a matter of debate. Hypothesizing (if not absurd) that all dinosaurs were wiped up with an impact of asteroids is also debatable.