03. Bachelor's Thesis

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Browsing 03. Bachelor's Thesis by Subject "Baleen whales"

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    AN ENDEMIC BALEEN WHALE FROM THE LATE MIDDLE MIOCENE OF ANCIENT EASTERN PARATETHYS SEA, KARAGIYE.
    (Nazarbayev University School of Mining and Geosciences, 2024-04-26) Kadirbek, Dias
    The easternmost part of the Cenozoic Eurasian megalake known as the Eastern Paratethys was in what is known today as Kazakhstan. It is one of the largest basins of the Parathetys and its sediments are well exposed in the Karagiye Depression south east of Aktau. In this depression, the late Middle Miocene to early Late Miocene (13.1-10.6 Ma) is very well represented, containing remnants of a unique and exceptionally rich endemic marine fauna. This fauna includes whales, dolphins, seals, sharks, and fishes from the Eastern Paratethys. Here, recently discovered new remains of whales from the Karagiye Depression have been studied. They have been identified as Otradnocetus virodovi. The remains include two cranial bones (tip of the mandible and posterior part of the rostrum), two vertebrae (thoracic and cervical vertebrae), four forelimb bones (two scapula parts, humerus and radius), two rib fragments and a hyoid bone. Stratigraphic ages of the studied bones (based on bio- and magnetostratigraphic studies) range from 13.1-13.0 Ma to 12.4-12.0 Ma. The bone measurement follows Mchedlidze (1984), Gol'din et al. (2014), Gol'din (2018), and references therein. Based on the anatomic and osteological peculiarities of the listed bones, it was possible to show that they belong to the species Otradnocetus virodovi, superfamily Cetotherioidea. The forelimb bones showed high diagnostic features of Otradnocetus virodovi, the vertebral bones showed high similarity with previously described specimens, the cranial and rib bones matched outlines of the Otradnocetus virodovi. Otradnocetus virodovi was originally described by Mchedlidze in 1984 from the Middle Miocene of North Caucasus. The vertebrate finds from the Karagiye Depression broadened the paleobiogeographic distribution of many Miocene Paratethyan marine species from Eastern and/or Central Paratethys. Otradnocetus is one of the earliest cetotheres findings. Its fossil record from Karagiye is the third find from Paratethys showing that this megalake was the region where this dwarf baleen whales evolved before their spreading to the global ocean.