Vue d'artiste Bashanosaurus primitivus

A new species of stegosaurus discovered in China

China was recently the site of the discovery of a fossilized stegosaurus considered to be the oldest ever found in Asia, and probably in the world.

Being a species that existed about 170 million years ago, during the Bajocian era of the Middle Jurassic, the specimen found seems small for a stegosaurus. It was only 2.8 meters long from its nose to the end of its spiny tail. The other stegosaurs could reach 9 meters in length.

It is not yet known whether the animal found was an adult or a baby, but its discovery could provide more answers on the evolution of the genus “stegosaurus”.

Specimen differs from Middle Jurassic stegosaurs

Stegosaurus are among the most popular Jurassic dinosaurs. They were herbivorous and had armor plates along their spine. They also had spikes that protruded from the end of their tails. The animal was quadrupedal with a very small head compared to its body.

The specimen found in China was baptized Bashanosaurus primitivus. His remains consisted of bones from the shoulder, back, thigh, feet, spine, and ribs. There were also several armor plates. A team of paleontologists led by Dai Hui from the Chongqing Bureau of Geological and Mineral Resource Exploration and Development compared them with those of other stegosaur species.

They discovered that Bashanosaurus primitivus had characteristics common to stegosaurs with a few differences. For example, its shoulders were smaller and less developed, its femur slightly different, and its armor plates were narrower but thicker at the base. According to Hui, Bashanosaurus primitivus clearly represents a new species of stegosaurus.

Common traits with older stegosaurs

Besides its physical similarities to stegosaurs, Bashanosaurus primitivus has some characteristics similar to those of the first armored dinosaurs. The latter lived some 20 million years earlier. This fact could make Bashanosaurus primitivus the missing link between these ancient dinosaurs and the more recent stegosaurs.

The study of the stegosaur family tree also showed that the specimen was among the first divergent stegosaurs. Some of its physical traits were also similar to those of thyreophores, the dinosaurs from which stegosaurs descended, and those of early stegosaurs like giantspinosaurus and Huayangosaurus. These similarities are found in particular at the level of the vertebrae of the tail which are more elongated and of the scapula which is more flared. There is also the absence of deep depressions in the vertebrae.

Bashanosaurus primitivus being ranked quite early in the stegosaur family tree, paleontologist Susannah Maidment of the Natural History Museum in London says this find suggests the group evolved around the early Middle Jurassic or even early Lower Jurassic.

China appears to have been home to a great diversity of stegosaurs, and one might also think from the results of the family tree analysis that the earliest stegosaur species originated in Asia.

SOURCE: sciencealert

Leave a Comment

Your email address will not be published.