중국에서 온 새로운 유형의 갑옷 공룡이 설명되었습니다. 그것들은 아시아에서 발견된 이 그룹의 가장 오래된 화석 유적이며, 이 이상한 공룡이 어떻게 진화하고 전 세계에 퍼졌는지에 대한 이해를 더해줍니다.

갑옷 공룡은 다음과 같은 유명한 동물을 포함하여 가장 유명한 공룡 중 하나입니다. 스테고사우르스 그리고 안킬로사우루스.

사실, 명명된 최초의 공룡 중 하나는 ‘아르마딜로’로 웨스트서섹스에서 발견된 안킬로사우루스의 일종으로 힐라오사우루스.

이 잘 알려진 종보다 훨씬 이전에 살았던 동물의 이 새로운 발견은 과학자들이 갑옷을 입은 공룡이 세계의 나머지 지역을 빠르게 식민지화하기 전에 처음 등장한 시기와 장소를 이해하는 데 도움이 됩니다.

초식 공룡에 초점을 맞춘 박물관의 공룡 연구원인 Paul Barrett 교수는 중국 동료들과 함께 새로운 종에 대한 설명을 도왔습니다.

화석 발견은 두개골의 일부, 척추, 팔다리의 일부, 그리고 수많은 갑옷을 포함한 완전한 골격으로 구성되어 있습니다. 아시아 전역에서 가장 오래 보존된 갑옷 공룡의 표본입니다.

“방패는 즉시 그것이 스테고사우르스 및 킬로사우르스와 같은 공룡 그룹의 구성원이라는 것을 말해주지만 공룡의 시대는 그것이 이 두 그룹 중 하나에 속하지 않는 초기 구성원임을 알려줍니다. 따라서 공통 그룹에 가깝습니다. 둘의 조상.”

설명하고 이름을 붙인 종이 유시사우루스 콥치키 잡지에 실렸습니다 이라이프.

동물의 뼈 외에도 많은 갑옷 조각이 발견되었습니다. 크레딧: © Xi Yao

갑옷 공룡의 기원

시[{” attribute=””>Jurassic and into the Cretaceous Periods a wealth of herbivorous dinosaurs evolved to be covered in extraordinary defensive bony plates, spikes, and knobs.

These dinosaurs are split into the stegosaurs on one side and the ankylosaurs on the other. The more famous stegosaurs, with their ridge of plates running along their backs and spiked tails, were large bulky animals, while the hulking ankylosaurs were generally covered in flat bony shields and were more like “walking coffee tables.”

Together, the stegosaurs and ankylosaurs are thought to have evolved from a shared ancestor and so form a group known as the thyreophorans, meaning “shield-bearers.” But there have long been questions about when and where this group evolved.

“My colleagues in China discovered this new armored dinosaur in Yunnan, southwest China, in rocks of Early Jurassic age dating to between 192-174 million years ago,” explains Paul. “When we put the animal into an evolutionary analysis, it came out close to the common ancestry of stegosaurs and ankylosaurs.

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

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

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

This historic paucity of finds from the southern continents has led to some suggesting that the group must have evolved in the north. But recent finds are muddying this opinion, with both the earliest known ankylosaur and stegosaur unearthed in the same rock formation in Morocco and dating to around 165 million years ago.

“There are early armored dinosaurs starting to turn up more in the south,” explains Paul. “There are two animals from about 200 million years ago from Venezuela and South Africa, that don’t have armor, but might be the earliest members of the group, showing what they looked like before they evolved armor.

“If these animals were in the group then it is likely the armored dinosaurs originated in the southern continents, but this idea is controversial. If they aren’t included in the group, then the origins are anchored in the northern hemisphere. At the moment, we’ve no way to choose between these alternatives.”

The new find helps to fill out what we know about this part of the world during the Early Jurassic some 192-174 million years ago. Credit: ©Yu Chen

A cosmopolitan dinosaur

This new discovery is not the earliest-known member of this group, but a contemporary of a number of other species from around the world, such as species in Germany and the UK. What this find does do is help to fill in the picture of what this region in China looked like at this moment in time and how these animals were evolving.

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

The fact that Yuxisaurus dates to the Early Jurassic is also of interest. The animal is different from the other early armored dinosaurs as it has a stockier build and a distinctive arrangement of armored 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.

“The armored dinosaurs appeared at the start of the Jurassic and within a few million years were already evolving into quite a few different types,” explains Paul. “In addition to that they achieved a worldwide distribution very early in their history.

“A bunch of really early members of stegosaurs and ankylosaurs from slightly later in time have been found spread around 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 finds are showing that this was not true.”

Reference: “A new early branching armored dinosaur from the Lower Jurassic of southwestern China” by Xi Yao, Paul M Barrett, Lei Yang, Xing Xu and Shundong Bi, 15 March 2022, eLife.
DOI: 10.7554/eLife.75248