New species of armored dinosaur discovered in China

This is the earliest armored dinosaur found in all of Asia, and it helps us understand when and where these animals first appeared. Credit: © Yu Chen

A new species of armored dinosaur has been described in China. These are the earliest fossil remains of this group found in Asia, providing insight into how these curious dinosaurs evolved and spread around the world.

Armored dinosaurs are some of the most recognizable dinosaurs, including famous animals such as stegosaurus and Ankylosaurus.

In fact, one of the first dinosaurs to be named was an armored dinosaur, a species of ankylosaur discovered in West Sussex known as the hyleosaurus.

This new discovery comes from an animal that lived long before any of these well-known species and helps scientists understand when and where armored dinosaurs first appeared before rapidly colonizing the rest of the world.

Professor Paul Barrett, a dinosaur researcher at the Museum who focuses on herbivorous dinosaurs, helped describe the new species with his Chinese colleagues.

“The fossil find consists of a fairly complete skeleton, including pieces of skull, vertebrae, parts of limbs, and plenty of armor. It is the best-preserved and oldest example of an armored dinosaur of any Asia.

“The armor immediately tells us that it’s part of the same group of dinosaurs as the stegosaurs and the ankylosaurs, but the age of the dinosaur tells us that it’s an early member, which is just outside the dinosaurs. ‘one of these two groups, and is therefore close to the common ancestor of the two.

The paper describing and naming Yuxisaurus kopchicki was published in the journal eLife.

New Asia Armored Dinosaur Skeleton

In addition to the animal’s bones, a large number of pieces of armor have also been unearthed. Credit: ©Xi Yao

The origin of armored dinosaurs

During the Jurassic and in the Cretaceous Periods when multitudes of herbivorous dinosaurs evolved to be covered in extraordinary defensive bone platesspikes and buttons.

These dinosaurs are divided into stegosaurs on one side and ankylosaurs on the other. The most famous stegosauruswith their crest of plates running down their backs and pointed tails, were large, bulky animals, while the massive ankylosaurs were usually covered in flat bony shields and looked more like “walking low tables”.

Together, stegosaurs and ankylosaurs are thought to have evolved from a common ancestor and thus form a group known as thyreophores, meaning “shield bearers”. But we wonder for a long time when and where this group evolved.

“My colleagues in China discovered this new armored dinosaur in Yunnan, southwest China, in rocks dating to the Early Jurassic period between 192 and 174 million years ago,” Paul explains. “When we placed the animal in an evolutionary analysis, it was found to be close to the common ancestry of stegosaurs and ankylosaurs.

“It helps to confirm that the first armored dinosaurs lived in this region at that time. We know very little about the general early history of herbivorous dinosaurs in China, so regionally this is a really important discovery. .

New excavation of armored dinosaurs in Asia

This part of China is rich in dinosaur fossils, but was largely dominated by sauropods and their relatives. Credit: ©Shundong Bi

In the past, thyreophoric dinosaurs were widely associated with rocks from the Late Jurassic and Cretaceous periods (163–66 million years ago) of North America and Europe. This revealed an incredible diversity of species, but it has long been known that their origins must go back much further.

This historical scarcity of finds from the southern continents has led some to suggest that the group must have evolved in the north. But recent discoveries cloud this opinion, with the earliest known ankylosaurs and stegosaurus having been discovered in the same rock formation in Morocco and dating to around 165 million years ago.

“There are the first armored dinosaurs that are starting to show up more in the south,” Paul explains. “There are two animals from about 200 million years ago from Venezuela and South Africa, which have no armor, but which could be the first members of the group, showing what they looked like before they develop armor.

“If these animals were part of the group, it is likely that the armored dinosaurs originated in the southern continents, but this idea is controversial. If they are not included in the group, then the origins are rooted in the northern hemisphere At the moment, we have no way to choose between these alternatives.

New Armored Dinosaur Asia

The new discovery helps complete what we know about this part of the world in the early Jurassic period around 192 to 174 million years ago. Credit: © Yu Chen

A cosmopolitan dinosaur

This new find is not the first known member of this group, but a contemporary of a number of other species around the world, such as species in Germany and the UK. This discovery helps paint a picture of what this region of China looked like at that time and how these animals evolved.

This particular formation in China has revealed other dinosaur fossils, but so far it is dominated by large, long-necked sauropods and their earliest relatives. This new discovery adds to the diversity of other herbivores that were also expected to be present in the ecosystem at the time.

The fact that Yuxisaurus Lower Jurassic dates are also of interest. The animal is different from other early armored dinosaurs because it has a stockier build and a distinctive arrangement of armor plates that would have covered its back. This suggests that these early animals were experimenting with their body shapes and ecology earlier than scientists previously thought.

“Armored dinosaurs appeared in the early Jurassic and within a few million years were already evolving into several different types,” Paul explains. “On top of that, they achieved worldwide distribution very early in their history.

“A group of very early stegosaur and ankylosaur members from somewhat later in time were found distributed throughout the world, so they must have been able to move across and between continents.

“Until recently, we assumed that all armored dinosaur evolution happened in the north, but new findings show that wasn’t true.”

Reference: “A New Armored Early Branching Dinosaur from the Lower Jurassic of Southwest China” by Xi Yao, Paul M Barrett, Lei Yang, Xing Xu, and Shundong Bi, March 15, 2022, eLife.
DOI: 10.7554/eLife.75248

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