Translartion. Region: Russians Fedetion –
Source: Novosibirsk State University – Novosibirsk State University –
As part of Darwin Week at Novosibirsk State University, Associate Professor of the Department of Historical Geology and Paleontology Faculty of Geology and Geophysics of NSU, PhD Igor Kosenko spoke about the Jehol biota, a unique ecosystem of the Cretaceous period discovered in China at the end of the last century, and how this discovery changed scientists’ understanding of dinosaurs and their contemporaries.
— Over the past century and a half, our views on dinosaurs have changed significantly more than once. At first, they were imagined as huge, clumsy reptiles; by the middle of the 20th century, thanks to new finds, it became clear that many of them walked on two legs. By the end of the last century, the majority of dinosaurs appeared to us as small, nimble predators that hunted large herbivorous dinosaurs in packs. And the latest discoveries have shown us that some dinosaurs were not just small, warm-blooded predators, but also covered in feathers, — said Igor Kosenko.
The latest findings were made possible by discoveries related to the Jehol biota, an ecosystem of the Lower Cretaceous (between 133 and 120 million years ago) that left fossils in the Yixian Formation and Jiufotang Formation in northeastern China.
— One of the most important properties of the Jehol biota was the fantastic preservation of the objects that make it up. And this allowed paleontologists to learn much better what the world was like 120 million years ago, — Igor Kosenko emphasized.
Typical representatives of this ecosystem are the Lycoptera fish, the Eosestheria conchostracans (freshwater bivalve crustaceans) and the Ephemeropsis mayfly larvae. But much more interesting were the fossils, which had completely atypical (for paleontology at the end of the last century) details.
The most fantastic find is probably the feathered dinosaur – Sinosauropteryx. In the same rocks, imprints of pterosaurs with hair-like structures were found. It turns out that these creatures were covered with fur. Another unique find is the imprints of feathered dinosaurs microraptors. In combination, these finds indicate that some kind of covering (hair or feathers) was typical of at least a number of dinosaurs. It is not for nothing that many scientists claim that they were closer to birds than to lizards.
Thanks to the amazing preservation of fossils, scientists were able to learn much more not only about the appearance, but also the habits of dinosaurs. The discovery of skeletons of a dinosaur and a mammal fighting with each other confirmed that serious competition had already begun between these types of animals at this time. The location of other skeletons showed that in some dinosaur species, adults could guard flocks of cubs, and, judging by the number of such groups, these “caregivers” were grazing not only their own offspring, and this already speaks of a rather complex group hierarchy.
Dinosaurs are not the only finds of paleontologists. In particular, the Jehol biota includes finds of some of the first angiosperms, which today are one of the most numerous groups of higher plants. But this is now, and initially the planet was dominated by gymnosperms – conifers and ferns. Fossils found in China made it possible to more accurately determine the boundaries of the beginning of the era of angiosperms, which then quickly took the leading positions. And their very first representatives grew in water bodies and were somewhat akin to water lilies.
Recorded fossil finds belonging to the Jehol biota are not limited to the territory of modern China. The northernmost of them were discovered in Transbaikalia.
— There is a famous joke about Russia being the homeland of elephants. With elephants, of course, this is debatable. But the most ancient fossils of this ecosystem were recorded here, and the first finds were also made not in China, but here, by the Russian scientist Middendorf before the revolution. He was the first to describe the location of the fossil fauna “Turga”, which is now also known as the “Middendorf outcrop”. Excavations there continue and regularly bring a variety of interesting finds, — Igor Kosenko emphasized.
Thus, in the Kulinda valley in the Transbaikal region, the remains of another feathered dinosaur were found, called “Kulindadromeus zabaikalicus”. Despite its feathers, it could not fly, and is considered the most ancient non-avian feathered dinosaur to date.
Scientists from the A.A. Trofimuk Institute of Petroleum Geology and Geophysics of the Siberian Branch of the Russian Academy of Sciences managed to clarify the age of the Turginskaya suite in the Middendorf outcrop, which had previously been the subject of debate in the scientific world. Fossil pollen of flowering plants was found in the samples, which made it possible to date them with a high degree of accuracy. According to their estimates, the age of the fossils may be about 125 million years, which made it possible to speak of these finds as the most ancient part of the biota.
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