Immediately recognizable by their massive columnar dorsal plates with their spines, their long tails and their small heads, stegosaurs were herbivorous dinosaurs that lived in the Jurassic and Early Cretaceous. Stegosaurus fossils have been found on every continent except Antarctica and Australia, and 14 species of Stegosaurus have been identified so far. Their origin is still poorly understood, but the discovery of this new fossil in southwestern China may finally provide the first answers.
a dinosaur from the middle jurassic
baptized animal Bashanosaurus primitivus Lived in the period between -170 and -168 million years, more precisely in the Bajosian, during the Middle Jurassic. The remains of Stegosaurus, which included bones from the back, shoulders, thighs, legs and ribs as well as several armor plates, were examined by Chinese and British paleontologists, who published their findings. Journal of Vertebrate Paleontology, They indicate that this dinosaur, which should have been a little less than 3 meters in length, has features Different from all other Middle Jurassic stegosaurids discovered so far. However, it is similar to some of the earliest armored dinosaurs, which are more than 20 million years old.
These similarities include long-tailed vertebrae, a narrower, flared scapula, and dorsal vertebrae similar to those of the earliest known armored dinosaur Skelidosaurus, which lived in early Jurassic North America and China. Bashanosaurus remains also reveal a number of features that make it unique from other known stegosaurs. For example, the tip of the bone at the end of the scapula is shorter and less well developed than in other stegosaurs, a bony projection of the femur is located below the middle of the diaphysis, and the bases of the bony plates curve upward. Huh. The plates are thicker than the others.
An Asian origin for stegosaurs?
With the discovery of this new species, the mystery of the origin of Stegosaurus begins to unravel: Bashanosaurus primitivus In fact early stegosaurs such as Huangosaurus and Gigantespinosaurus and early Thyrophorus have similar characteristics, a suborder comprising armored dinosaurs. This strongly suggests that China was a hotspot for stegosaur diversification as they are found at various times from the Middle Jurassic through the Cretaceous. For the authors, the presence of stegosaurs in the Middle Jurassic also points to an Asian origin of this group that may have appeared about 10 million years ago.
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