Translation. Region: Russian Federation –
Source: Novosibirsk State University –
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The permanent exhibition "Mesozoic: Continental Flora and Fauna" has been expanded with a new display case featuring specimens of Cretaceous lake fauna—remains of bony fish, insects, and crustaceans. These specimens were collected by staff from the "Evolution of the Earth" Scientific and Educational Center. Faculty of Geology and Geophysics of Novosibirsk State University and the A.A. Trofimuk Institute of Petroleum Geology and Geophysics (IPGG) of the Siberian Branch of the Russian Academy of Sciences during expeditions to the Trans-Baikal Territory. The exhibition also includes finds from China, provided by Igor Kosenko, Associate Professor of the Department of Historical Geology and Paleontology at NSU's GGG. The uniqueness of all the specimens lies in their excellent preservation—the structure of these prehistoric creatures can be seen in exquisite detail, even with the naked eye.
The new display case presents animals belonging to the Jehol fauna. These are the fossil remains of feathered dinosaurs, birds, mammals, and plants, found in large numbers in the Lower Cretaceous deposits of northeastern China. Such localities are called lagerstätten. This is a special type of fossil burial that preserves not only the hard parts of skeletal forms but also impressions of soft tissue. Lower Cretaceous deposits containing the remains of the Jehol biota are very widespread—from Transbaikalia, Russia, in the north and Japan in the east, to Guangdong Province, China, in the south and the Xinjiang Uyghur Autonomous Region of China. Deposits characterized by typical representatives of the Jehol biota are widespread in Transbaikalia. These include the remains of crustaceans (Eosestheria conchostracans), insects (Ephemeropsis mayfly larvae), and bony fishes (Lycoptera). All of these prehistoric lake animals are on display in a new display case, said Vsevolod Efremenko, an engineer at the Evolution of the Earth Research Center and a junior researcher at the Institute of Petroleum Geology and Geophysics (IPGG SB RAS).
The Jehol Biota is a distinct lake fauna and flora characteristic of Asia. It encompasses China, Mongolia, the Transbaikal Territory, and parts of Korea. This fauna has been known for some time and was first described from finds made in the Transbaikal Territory. However, it gained notoriety and its current name after the discovery of feathered dinosaur footprints in China. Scientists from the Novosibirsk State University Geological and Geophysical Institute and the Institute of Petroleum Geology and Geophysics (IPGG SB RAS) have been studying the Jehol Biota in the Transbaikal Territory since 2021. An expeditionary team for paleontological research in the Transbaikal Territory was formed four times—in 2021, 2022, 2024, and 2025. The materials presented in the exhibition were collected during the 2021 and 2024 expeditions. A new expedition is planned for 2026.
The new display case features specimens of Jehol lake fauna from Transbaikal and China. The most striking, of course, are the fish. Among them is an ancient paddlefish—a sturgeon-like fish called Protopsephurus, which appeared in the Mesozoic era and spread across the planet. Also on display is a remarkably well-preserved bony fish called Lycoptera, quite common in the Mesozoic era. The specimen clearly displays scales that have retained their original position. For this reason, even the lateral line—a sensory organ that runs along the body—is visible on the fish's body. It senses the movement and vibrations of the water, helping the fish navigate, navigate obstacles, move in a school, and avoid predators.
Fishes of the genus Lycoptera were widespread across Asia approximately 120 million years ago, and paleontologists encounter such finds quite frequently. However, many specimens often have scales that are displaced and the lateral line is destroyed. Here, however, it is clearly visible. This means that the scales remained in place from the moment of death until burial, and the fish itself was preserved in ideal conditions. Thanks to these conditions, another specimen was also perfectly preserved—the largest fish skeleton on display. This is an Irenichthys, with a body length of approximately 15-18 cm. This is the largest complete skeleton of this species we have found—these fish typically do not grow to such a size. All the bones of the skeleton and scales are clearly visible, and the structure of the skull is clearly visible. A detailed description of the entire species could be compiled from this specimen. This specimen, like the previous one, was preserved in ideal conditions, which is why it is so beautifully preserved. But other fish of the same species, whose imprints are on display, were less fortunate—they are slightly deformed, their scales damaged. "It's likely that optimal conditions were periodically disrupted in the places where they were preserved," explained Vsevolod Efremenko.
In addition to Cretaceous fish, the exhibition also features crustaceans and insects: shield bugs, mayfly larvae, and beetles. They are as well preserved as the fish—all body segments, legs, tiny claws of small crustaceans, and antennae are clearly visible. Some insects even retain egg clutches and the internal structure of their bodies. A magnifying glass is sufficient to fully appreciate such fine details, but they are also visible to the naked eye. The silhouettes of mayflies with their triple tails are slightly less distinct on the stone slabs. On some specimens, the outlines of small fish can be seen among the numerous crustaceans.
— Locations where creatures that lived for tens or hundreds of millions of years have been preserved in ideal conditions and in wide diversity are called lagerstätt. For paleontologists, these are real treasure troves. There are several of them in Transbaikalia, and we worked at these locations. It should be noted that the lakes themselves are no longer preserved; we are working with the fossilized sediments of these paleolakes. In one such ancient reservoir, a large variety of fish was preserved in abundance, while in another, for some reason, they were not found, but many shieldfish and insects were found. To ensure such preservation for living beings and “preserve” them for many tens of millions of years, a number of conditions must be met. The animal must end up on the muddy bottom of the reservoir in an oxygen-free environment. An important condition is the absence of predators or scavengers who would eat the remains of a dead animal. In these places there should be no currents or other hydrodynamics that could disrupt the integrity of the remains. In addition, they should be gradually covered with sediment to protect them from adverse environmental influences. It is in such places that today one can study the ecology, paleobiology, food chains, and lifestyle of the lake inhabitants of the Mesozoic. Lagerstätts are also valuable because such unique specimens, which are presented in our exhibition, can be found by paleontologists without much difficulty, whereas at ordinary excavation sites the search for ancient creatures is a rather labor-intensive, lengthy task and does not guarantee success. The number of exhibits on our new showcase will be replenished, as we plan to continue to participate in excavations in the Transbaikal region,” said Vsevolod Efremenko.
The exhibition dedicated to the continental flora and fauna of the Mesozoic was recently supplemented by an installation of fragments of fossilized tree trunks. It aims to reflect the Mesozoic era as the kingdom of gymnosperms, which then reached its peak of biodiversity and distribution. Modern conifers are a well-known example of such plants. However, by the mid-Cretaceous, the first flowering plants appeared, which, by geological standards, began to displace their competitors quite quickly. Therefore, the diet of herbivorous dinosaurs at the end of the Cretaceous was already radically different from that of their Jurassic predecessors.
"When assembling the installation, we used more ancient, late Paleozoic fragments of fossilized cordaite trunks (Cordaitales) from Kuzbass, approximately 300 million years old, as the Evolution of the Earth Research Center has accumulated a large number of similar specimens, collected over the years by staff from the Geological and Geophysical Faculty of NSU. Cordaites are also gymnosperms, specifically primitive conifers. These were mighty trees, as tall as modern pines and cedars, but with large, lanceolate leaves that were shed seasonally," explained Alexander Igolnikov, head of the Evolution of the Earth Research Center.
Material prepared by: Elena Panfilo, NSU press service
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