Bashanosaurus primitivus is the earliest record of Stegosauria from Asia and represents one of the earliest records of this group of dinosaurs from anywhere in the world.
Stegosaurs were an iconic group of armored dinosaurs with enlarged patches of skin armor and/or spines extending from the neck to the tip of the tail.
Stegosaurus fossils have been found on every continent except Antarctica and Australia.
The first stegosaurs are known from the Middle Jurassic of Europe, China, Argentina and Morocco.
The diversity of stegosaurs seems to have decreased after the Jurassic period, and they seem to have disappeared in the middle Cretaceous. About 14 genera of stegosaurs are currently recognized.
The recently discovered species of stegosaurus roamed the Earth during the Middle Jurassic period, around 168 million years ago.
Scientific name Bashanosaurus primitivusthe ancient creature was about 2.8 m (9 ft) long.
It had a smaller, less developed blade, narrower, thicker bases for its armor plates, and other features that are unlike any other Middle Jurassic stegosaurs discovered so far.
However, it had similarities to some of the earliest armored dinosaurs, which are over 20 million years older.
“All of these features are clues to the place of stegosaurs in the dinosaur family tree,” said Dr. Dai Hui, a paleontologist with the Chongqing Geological and Mineral Resources Exploration and Development Bureau.
“Bashanosaurus primitivus stands out from other Middle Jurassic stegosaurs and clearly represents a new species.
The fossilized remains of Bashanosaurus primitivus – back, shoulder, thigh, foot and rib bones – were found in the Shaximiao Formation near Laojun Village, Chongqing Municipality, China.
“Our analysis of the family tree indicates that Bashanosaurus primitivus is one of the first divergent stegosaurs with chungkingosaurus and Huayangosaurussaid Dr. Hui.
“These were all found in the Middle to Late Jurassic Shaximiao Formation, suggesting that stegosaurs may have originated in Asia.”
“The discovery of this Middle Jurassic stegosaurus from China adds to a growing body of evidence that the group evolved during the Early Middle Jurassic, or possibly even the Early Jurassic, and as such represents some of the earliest dinosaurs to rumps of known birds,” said Dr Susannah Maidment, a paleontologist at the Natural History Museum in London.
“China appears to have been a hotspot for stegosaur diversity, with many species now known from the Middle Jurassic through the Late Lower Cretaceous.”
The team’s article was published in the Journal of Vertebrate Paleontology.
Dai Hui et al. New Middle Jurassic Lower Limb Stegosaurs from the Shaximiao Formation of Chongqing, China. Journal of Vertebrate Paleontology, published online March 3, 2022; doi: 10.1080/02724634.2021.1995737