Translation. Region: Russian Federation –
Source: Novosibirsk State University –
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Scientists from the Laboratory of Nuclear and Innovative Medicine performed CT scans of five jaw fragments from woolly rhinoceroses that inhabited southern Siberia during the Pleistocene. Faculty of Physics of Novosibirsk State UniversityHigh-quality 3D images of valuable finds allow paleontologists to understand how these ancient animals changed their teeth and compare the data obtained with modern rhinoceroses, which are endangered. Tomographic studies provide scientists with valuable information about paleontological specimens that is impossible to obtain using other research methods. The image of the object is scanned in three projections. It can be rotated, zoomed in, zoomed out, and fragmented.
“The paleontological samples under study are interesting because they are fragments of the jaws of not adult individuals, but of young ones, the estimated age of which is from 3.5 to 5 years and, possibly, a little older. It was at this age that baby woolly rhinoceroses changed their milk teeth to permanent ones. This process is long, and we are interested to know exactly how it happened. It is possible to find out to what extent permanent teeth were formed in the animals from which the specimens we studied originated, only by looking inside the jaw. There are only two options to do this. The first is to disassemble the jaw fragment mechanically and see how it is arranged inside. But for paleontological samples this is extremely undesirable, since their integrity will be damaged, and the sample itself, which is of scientific value, will be lost. The second option is to conduct a CT scan of the samples, study the resulting images and obtain the necessary information without destroying the samples. Therefore, we chose the second path. Thanks to him, we will try to understand at what age each individual died and correlate the data obtained with those that are typical for modern rhinoceroses. In this way, we will be able to establish whether the development of woolly rhinoceroses was similar to the development of modern rhinoceroses, or whether there were any differences between them,” said a senior researcher at the Laboratory of Lithogeodynamics of Sedimentary Basins at the Institute of Geology and Mineralogy. V.S. Soboleva Dmitry Malikov.
Preserving the integrity of the specimens is particularly important in this case. While skeletal remains of adult woolly rhinoceroses are relatively common, discoveries of similar specimens from calves are very rare. Their bones are much more fragile than those of adult animals, which directly impacts their preservation. Five dental specimens were submitted for study: four large jaw fragments and one almost complete lower jaw. Some specimens contain only deciduous teeth, clearly belonging to individuals who had not yet reached the age of tooth replacement. In others, partially erupted permanent and partially worn deciduous teeth are visible. In one of these, a permanent tooth can be seen almost displacing a deciduous tooth. In the most complete jaw, one can see how the bone tissue was torn to expose the formed permanent molar. This process is less noticeable in the other specimens.
"Computer tomography images will allow us to see the formation of permanent teeth and the displacement of deciduous teeth within the jaw body. This will allow us to more accurately assess the sequence in which these processes occurred, allowing us to compare them with similar processes in living rhinoceroses. This will allow us to estimate the size of permanent teeth that have not yet erupted and to determine how woolly rhinoceros calves may have differed in size not only from adults but also from other calves of similar ages," explained Dmitry Malikov.
The geological age of the studied samples ranges significantly—from 120,000 to 15,000 years ago. They were discovered in the southern Krasnoyarsk Krai, the Altai Krai, and the Irkutsk Region. These findings formed the basis for the research work of Dmitry Malikov and his colleague, paleontologist, PhD in Geographical Sciences, and research fellow at the Laboratory of Mesozoic and Cenozoic Geology at the Institute of the Earth's Crust SB RAS, Alexey Klementyev, who provided several samples for CT scanning.
A remarkable specimen was found in the bed of the Likhachev Stream near the village of Ust-Kozlukha in the Krasnoshchyokovsky District of the Altai Territory in June 2021.
"A series of studies has established that the age stages of the woolly rhinoceros are similar to those of modern white and black rhinoceroses, allowing us to determine the individual age of fossil remains. Their teeth also erupt in the same order and at approximately the same time. This suggests that this individual was three years old at the time of its death. Around this age, modern rhinoceroses are separated from their mothers when their next offspring are born. This calf was likely not ready for independent life. Perhaps the young animal lacked the experience to survive its first winter on its own," explained Dmitry Malikov.
As Ulyana Krechetova, a CT scanner operator at the NSU Laboratory of Mathematics and Physics, explained, the samples were scanned using a standard dental mode, which is typically used for similar studies of living specimens. However, additional adjustments were required because the samples being examined are larger and more dense than living tissue.
"Computer tomography is indispensable in such studies, when it is necessary to study the internal structure of a sample without destroying it. The NSU Laboratory of Paleontological Research has conducted numerous studies of paleontological specimens, and we continue to accumulate experience in this field. The images we obtain will be interpreted and studied in detail, with results planned for this year. They may reveal previously unknown information about the ecology, evolution, and developmental characteristics of these representatives of Siberia's ancient fauna. For our laboratory's researchers, studying such unusual objects is a scientific endeavor in itself, aimed at determining the optimal working conditions for such specimens. Our research will continue with the creation of three-dimensional models. We will explore solutions to enhance the clarity of the data obtained and facilitate its use by paleontologists," said Vladimir Kanygin, Head of the NSU Laboratory of Paleontological Research.
According to Dmitry Malikov, research into the remains of prehistoric fauna can contribute to the preservation of modern biological diversity.
"Currently, most large mammals, including rhinoceroses, are endangered. This further complicates the work of scientists, as some types of research require the capture of an animal for scientific purposes and in-depth study in a laboratory. Naturally, in such cases, the animal is permanently removed from the wild. However, for endangered species, the loss of even one individual is quite significant for the population, so such studies are conducted extremely rarely. Studying fossil specimens and comparing them with their living relatives could be a solution to this problem," said Dmitry Malikov.
Last year, the Laboratory of Nuclear and Innovative Medicine of the Physics Faculty of NSU conducted tomographic scanning of defective mammoth tusksAnd bone remains of ancient horses.
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