A fresh theory on the origin of dinosaurs shakes up a central fact regarding the ancient creatures that has stood for 130 years.
The new view, published in the journal Nature, redraws the two major branches of the dinosaur family tree, leading to a claim that the currently accepted theories on the evolution of dinosaurs and the place of their origin are wrong.
Two Major Dinosaur Groups Reclassified
Since 1887, dinosaurs have been divided into two major groups, namely the lizard-hipped saurischians and the bird-hipped ornithischians. The saurischians can then be further divided into the meat-eating theropods, which includes the Tyrannosaurus, and the long-necked sauropodomorphs, which includes the Brontosaurus. Meanwhile, falling under ornithischians are horned dinosaurs such as the Triceratops and armored dinosaurs such as the Stegosaurus.
However, the new dinosaur study by University of Cambridge Ph.D. student Matthew Baron redraws the classifications, after the comparison of 74 early dinosaurs and their relatives.
In Baron's redrawn dinosaur family tree, the saurischians now only include the sauropodomorphs, and the theropods were grouped with ornithischians to form a new classification named ornithoscelidans.
The Atlantic's Ed Yong, who claims he actually gasped upon reading Baron's study, explains the change vividly. Yong said that the reclassification is like telling people that what they know as cats and dogs is wrong, and that some of the animals they know as cats are actually dogs.
Harry Seeley, a British paleontologist, first proposed the split of saurischians and ornithischians back in 1887, with the classifications based on the shape of the hips of the dinosaurs. With the seemingly obvious difference, succeeding researchers simply accepted the proposal and went into their studies without rigorously testing the idea that Seeley conceived.
However, when Baron studied the few specimens available from the earliest dinosaurs, he found that early ornithischians oddly resembled theropods. This led to a three-year gathering of data that covered 74 dinosaur and dinosaur-adjacent species, leading to the proposal of a revised dinosaur family tree.
Revised Family Tree Shakes Up Dinosaur Facts
With the proposed revisions on the dinosaur family tree, changes to the origins of the ancient beasts have also been suggested.
It was suggested that dinosaurs first appeared about 245 million years ago, which is earlier by about 15 million years than what was previously believed.
Fossil evidence also suggested that dinosaurs possibly originated in the northern part of the planet on the land mass known as Laurasia, in what is now the United Kingdom, instead of on the southern region known as Gondwana.
"The northern continents certainly played a much bigger role in dinosaur evolution than we previously thought and dinosaurs may have originated in the UK," Baron told BBC News.
Two crucial fossils have been found in England and Scotland, and for decades, they were dismissed as having no significant importance. However, with the redrawn dinosaur family tree, these two fossils are now placed in the spotlight, as they are now known to be located near the site of the origin of dinosaurs.