New species of stegosaur is oldest discovered in Asia, and possibly the world

According to research published today in the Journal of Vertebrate Paleontology, a new species of dinosaur is the oldest one ever found in Asia, and one of the earliest in the world.

The remains of the stegosaur, which included bones from the back, shoulder, thigh, feet, and ribs, as well as several armor plates, are much earlier than most known stegosaurs.

A team from the Chongqing Bureau of Geological and Mineral Resource Exploration and Development in China and London's Natural History Museum named it Bashanosaurus primitivus in reference to the ancient name for the area of Chongqing in China.

The new dinosaur, which was on the planet 168 million years ago, plays a part in uncovering how the stegosaurs evolved.

It has a smaller and less developed should blade, narrower and thicker bases to its armor plates, and other features that are different from all other Middle Jurassic stegosaurs discovered so far. It is similar to some of the first armored dinosaurs, which are over 20 million years old.

According to Dr. Dai Hui from the Bureau of Geological and Mineral Resource Exploration and Development, the features are clues to the place on the dinosaur family tree.

Our analysis of the family tree shows that it is one of the earliest-diverging stegosaurs along with the Chongqing Lizard. These were unearthed from the Middle to the Late Jurassic Shaximiao Formation in China, suggesting that they may have originated in Asia.

Stegosaurs were four-legged, plant-eating dinosaurs that lived during the early days of the dinosaurs. Stegosaur fossils have been found in all of the world except for Australia and Antarctica.

One of the most primitive stegosaurs, the Huayangosaurus, is one of the well-known members of the group. Attempts to understand how the stegosaurs evolved and how they relate to one another have been hampered by the fragmentary fossil material.

The mystery has started to clear up after the discovery of this new species. The primitive features of Bashanosaurus primitivus are similar to those of the earliest dinosaurs. There are features of the back of the dinosaur that are similar to the early armored dinosaur Scelidosaurus, as well as a shoulder blade that is narrower and flares out.

The features of Bashanosaurus make it unique from other stegosaurs. The thighbone is positioned below the middle of the shaft and the bases of the armor plates curve out.

The discovery of this stegosaur from the Middle Jurassic of China adds to an increasing body of evidence that the group evolved in the early Middle Jurassic, or perhaps even in the Early Jurassic, and as such represent some of the earliest known bird-hipped dinosaurs.

China seems to have been a hot spot for stegosaur diversity, with numerous species now known from the Middle Jurassic right the way through until the end of the Early Cretaceous period.

More information: Dai Hui et al, New Stegosaurs from the Middle Jurassic Lower Member of the Shaximiao Formation of Chongqing, China, Journal of Vertebrate Paleontology (2022). DOI: 10.1080/02724634.2021.1995737 Journal information: Journal of Vertebrate Paleontology Citation: New species of stegosaur is oldest discovered in Asia, and possibly the world (2022, March 4) retrieved 4 March 2022 from https://phys.org/news/2022-03-species-stegosaur-oldest-asia-possibly.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.