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168-million-year-old stegosaurs fossil suggests the iconic dinosaurs originated in Asia © Banana Art Studio

168-million-year-old stegosaurs fossil suggests the iconic dinosaurs originated in Asia

Published: 04th March, 2022 at 00:01
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The fossil is one of the oldest ever discovered and could shed light on the evolution of one of the world’s most instantly recognisable dinosaurs.

With its jutting armoured backplates, intimidating spiked tail, long neck and almost comically small head, the Stegosaurs is one of the most instantly recognisable dinosaurs ever discovered.

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The hulking, plant-eating dinosaurs roamed the Earth during the Jurassic and early Cretaceous periods more than 150 million years ago and fossils of the animals have been found on every continent save for Antarctica and Australasia.

So far 14 distinct species of stegosaur have been identified including Huayangosaurus, a more primitive species that had large spikes protruding from its shoulders, and Miragaia, a species known for its extremely long neck.

But thanks to the incomplete nature of many of the fossils, palaeontologists have struggled to piece together anything like a complete Stegosaur family tree.

Now, researchers from the Chongqing Bureau of Geological and Mineral Resource Exploration and Development in China have discovered the fossil of a Stegosaurus that features bones from the back, shoulder, thigh, feet, and ribs, and several armour plates that dates back 168 million years to the Bajocian stage of the Middle Jurassic period, making it the oldest ever found in Asia.

They named it Bashanosaurus primitivus. Bashan refers to the ancient name for the area of Chongqing in southwestern China where it was found, and primitivus is Latin for first.

At around 2.8m in length, Bashanosaurus was small for a Stegosaurs, though the researchers are unable to confirm if it was full grown or not. It also had smaller shoulder blades and slimmer armour plates compared to other known species.

“All these features are clues to the Stegosaurs’ place on the dinosaur family tree”, said research leader Dr Dai Hui from Chongqing Bureau of Geological and Mineral Resource Exploration and Development.

Bashanosaurus can be distinguished from other Middle Jurassic Stegosaurs, and clearly represents a new species.

“What’s more, our analysis of the family tree indicates that it is one of the earliest-diverging Stegosaurs along with the Chongqing Lizard (Chungkingosaurus) and Huayangosaurus. These were all unearthed from the Middle to Late Jurassic Shaximiao Formation in China, suggesting that Stegosaurs might have originated in Asia.”

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Authors

Jason Goodyer
Jason GoodyerCommissioning editor, BBC Science Focus

Jason is the commissioning editor for BBC Science Focus. He holds an MSc in physics and was named Section Editor of the Year by the British Society of Magazine Editors in 2019. He has been reporting on science and technology for more than a decade. During this time, he's walked the tunnels of the Large Hadron Collider, watched Stephen Hawking deliver his Reith Lecture on Black Holes and reported on everything from simulation universes to dancing cockatoos. He looks after the magazine’s and website’s news sections and makes regular appearances on the Science Focus Podcast.

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