Scientists study the evolution of bird-hipped dinosaurs

One question that has plagued scientists, specifically paleontologists, is where did the ornithischians come from. Most of the remains found from the Late Triassic Period are of saurischian dinosaurs, based on the lizard-hip bone structure. However, a new study on the Silesaurus from that time paints a new picture.

Led by the University of Cambridge, along with a team from Universidade Federal de Santa Maria based in Brazil, it seems there may be some new ideas. If the researchers are right, it could be that ornithischians evolved from saurischians during the passing of the Late Triassic Period into the Early Jurassic Period. Here are some details of the findings.

The Ornithischian Debate

When Richard Owen first named these ancient beasts dinosaurs in 1842, there was little we knew about them. Over time, we came to realize that they originated about 225 million years ago during the Late Triassic Period. The fossils we have found from that time all seem to have lizard-hip structures, which were classified as Saurischians.

But if Ornithischians only appeared in the Early Jurassic Period, where did these bird-hipped dinosaurs come from? They surely originated from somewhere. This is the latest research being undertaken by the University of Cambridge, assisted by Universidade Federal de Santa Maria based in Brazil.

Enter the Silesaurus

In the latest phylogenic hypothesis for Ornithischia, the researchers extensively looked into recent Silesaurus remains discovered. There was a report before that claimed both bird- and lizard-hipped dinosaurs all originated from the same prehistoric creatures with a common ancestor. It caused quite a bit of controversy, but it looks like the new research is steering in the same direction.

While the skulls seem to be missing some essential Ornithischian identification elements, the research shows that many aspects reveal that it may have been an Ornithischian from the Late Triassic Period. There’s only one problem with this finding: it has a lizard hip instead of bird.

Ornithischians might have evolved from Saurischians

With more Silesaurus fragments found in South America, it looks like it has a similar teeth structure to that of Ornithischians. It also looks like the genus is related to true dinosaurs from the earliest times, but it leaves so many questions. For example, is it a sister order to Ornithischia, or did it lead to the development of ornithischian dinosaurs?

The researchers suggest we look at it from a Darwinian perspective. There’s a good chance that all dinosaurs were saurischian in the Late Triassic Period and then evolved into the bird hips of ornithischians towards the Early Triassic. If this is true, then dinosaurs like Triceratops and Iguanodon might share Silesaurus as a common ancestor.

Images courtesy of University of Cambridge

Another possibility

Another reasoning the researchers have is that the ornithischians didn’t have a common ancestor with the saurischians and simply displayed different features in the Late Triassic Period. Yet, it still means that they evolved in some way, as we saw the lizard hips in the Silesaurus.

We might even go as far as to say that Silesaurus is simply a saurischian that has nothing to do with ornithischians, and the researchers are simply speculating at this point. However, it’s always good to have these debates and thoughts so that we can progress towards a proper answer in the future.

News source: University of Cambridge