Researchers in China have discovered fossil fragments of a previously unknown dinosaur. They named it “Baiyin reptile” (Baiyinosaurus baojiensis).
The Baiyin reptile lived about 165 million years ago, during the Middle Jurassic period. This dinosaur belonged to the Stegosauria group. These were plant-eating, armored dinosaurs living in the Jurassic and Cretaceous periods.
Stegosaurs grew to 30 feet long. They had small heads, peg-like teeth, and vertical bony plates and spines on their backs and tails. They also had hoof-like toes on all four limbs.
Dr. Li Ning and colleagues from the China University of Geosciences mentioned, “Stegosaurs are a minor but iconic clade of ornithischian dinosaurs, yet due to a poor fossil record, their early evolution is poorly understood.”
Characteristics of the new dinosaur species
Stegosaurs had two rows of large, bony plates or spines on their backs from neck to tail. They have been found everywhere except Antarctica and Australia.
These dinosaurs first appeared in the Middle Jurassic period. By the Late Jurassic, they had spread all over the world. However, they became less common in the Early Cretaceous period.
Baiyinosaurus baojiensis, a new mid-Jurassic stegosaur from China#paleo #paleoart #science #sciart #stegosaur #slayleoart pic.twitter.com/Z5ys6eHXXc
— dino dan (@ddinodan) July 2, 2024
Ning said that Middle Jurassic stegosaur fossils are very rare. There are only five known species from that time: Loricatosaurus from the United Kingdom, Isaberrysaura from Argentina, Adratiklit from Morocco, and Huayangosaurus and Bashanosaurus from China.
Researchers found part of the Baiyinosaurus baojiensis skeleton in the Wangjiashan Formation. This partial skeleton includes part of the skull, a neck bone, seven back bones, and a tail bone.
New dinosaur species is an early type of stegosaur
The area of study is in the northwestern part of the Baojishan Basin, located in the Pinchuan District of Baiyin City, Gansu Province, China. The Baojishan Basin is at the eastern end of the Qilian Mountains.
The dinosaur fossils were found in the upper part of the Straw-yellow Sandstone Member of the Wangjiashan Formation. Researchers used large plant fossils and pollen to date the area.
They also examined lake-dwelling invertebrates from the overlying Oil Shale Member. These included small crustaceans, green algae, and bivalves. Based on this evidence, they believe the Straw-yellow Sandstone Member dates back to the Late Bathonian Age.
The researchers’ analysis shows that Baiyinosaurus baojiensis was an early type of stegosaur related to Isaberrysaura, Alcovasaurus, Jiangjunosaurus, and Gigantspinosaurus.
The team found that Baiyinosaurus baojiensis has certain primitive features and is a transitional form between early armored dinosaurs and early stegosaurs.
The increasing variety of Middle Jurassic stegosaurs in early stages suggests that stegosaurs likely separated from their close relatives, the ankylosaurs, early in the Middle Jurassic period or even earlier.
