Scientists have found in Yakutia, the remains of two mammals in the time of dinosaurs

© Photo : April Neander, University of SDT the artist has imagined a warm-blooded fauna of Eurasia during the Jurassic periodScientists have found in Yakutia, the remains of two mammals in the time of dinosaurs© Photo : April Neander, University of STS to daily updates RIA Science

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Paleontologists from Germany and Russia found in the South of Yakutia, the remains of two ancient mammals, indicating the existence of a kind of «era of stagnation» in the life of polar fauna of the Earth in the late Jurassic and early Cretaceous period. Their findings were presented in the journal PLoS One.

«Primitive mammals, which we found in the Cretaceous sediments are actually «living fossils» of their time. It is believed that between the Jurassic and Cretaceous periods occurred quite serious extinction, but in Siberia occurred no fatal events and changes of fauna for about 40 million years. For comparison, the first humans appeared on Earth about 2.5 million years ago,» says Paul Skucas from Saint-Petersburg state University.

The first mammals appeared on the planet approximately 220-225 million years ago, towards the end of the Triassic period, along with the first primitive dinosaurs. After his appearance, the ancient warm-blooded animals quickly spread throughout the Land.

The first primitive members of our class were relatively small. Judging by the structure of their teeth, they ate a monotonous diet, mainly insects. Main boom their evolution began only after the dinosaurs became extinct, not allowing them to occupy new ecological niches.

Russian and German scientists has revealed one interesting detail from the life of ancient relatives of humans and other modern mammals, conducting excavations in the South of Yakutia, in the territory of Suntarsky district in the Republic, where it is overlain by rocks of the beginning of the Cretaceous period, formed 120-125 million years ago.

While Yakutia and the whole of Eastern Siberia were close to the North pole of the Earth, and therefore periodic opening balances «polar» dinosaurs and other animals has always aroused great interest among paleontologists.

A year ago, Skuchas and his colleagues began a new round of excavations in the area of Yakutia, studying sediments from the Cretaceous period, formed in the vicinity of the stream Taata. In addition to the remnants of the dinosaurs, as well as small reptiles, fish, turtles and other animals, scientists were able to find three fragments of jaws and teeth of mammals.

One of them belonged to a mammal from the group Haramein – presumably the oldest «real» mammals of Earth, and the other two representatives of previously unknown genera and species of warm-blooded creatures. All three were similar to modern shrews in size and diet, but of course they are not their ancestors or even relatives.

The first new mammal was named Khorotherium yakutensis in honor of Yakutia and the village of Horo, whose residents regularly help paleontologists to excavate on the banks of the Creek Teeta. The second was named Sangarotherium aquilonium, inheriting the name from the so-called «Tsugaru sediments», in which he found his teeth and fragments of jaw.

«They are representatives of two groups of primitive mammals — autecological and docodonta. The first teeth were like small tridents or three of their vertices are in one line, this is a very primitive structure. But docodonta their teeth tried to complicate: they have more bumps and have a chewing surface,» continues Skucas.

In that time the Earth was supposed to inhabit not only the first marsupials, but placental mammals, as evidenced by numerous finds of their remains in China, Mongolia and in other parts of the world.
Accordingly, the presence of the ancient eurekazone, docodonta and Haramein in Yakutia at the time suggests that its fauna was «frozen» and not changed for a very long time, tens of millions of years. As it happened, and touched on whether this «stagnation» of other animals – is not clear.

According to Skucas, his team will once again travel to the shores of the Creek Taate in the coming days to continue the excavations and the solution of this paleontological puzzle.

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