New Finds of Early Cretaceous Fossil Vertebrate Remains on the Territory of Yakutia pp. 141-146
Authors: (P.N. Kolosov, Diamond and Precious Metal Geology Institute, Siberian Branch of the Russian Science Academy, Yakutsk, Republic Sakha, Yakutia, Russia)
Abstract: Recent discoveries of dinosaur localities in high-latitude (polar) regions and the necessity of understanding the reasons why these prehistoric animals lived there in severe climatic conditions have aroused considerable interest in them [6, 9]. As noted by L. A. Nesov [6, p. 51], ―neither the hypothesis of migratory hadrosaurs nor that of their permanent residence in high-latitude areas can adequately explain how the process of incubating eggs occurred and how the adult and young dinosaurs passed the winter in northeast Russia‖. In the Late Mesozoic, the territory of present-day Teete was located somewhat north of 60° N in a polar region . The dinosaur localities in northern Alaska also had a similarly high-latitude position. There the average annual temperature ranged in the Late Cretaceous from a maximum +13oC to a minimum +2o . In the Neocomian, the average annual temperature in the Arctic basin did not exceed +15oC . This paper presents new factual material obtained from Teete, which suggests that in the Early Cretaceous (Berriasian-Barremian-Neocomian) armored ankylosaurs inhabited this locality (a polar region). The Teete (photo 1) locality represents outcrops extending laterally along the right bank of Teete Creek flowing from west to east. From bottom to top, the cross-section includes: 1. Grey sandstones in the Teete Creek mouth, with a yellow weathered surface (visible thickness is 0.3 m). They contain horsetail remains. Higher up occurs a 4-m thick talus-covered horizon. The talus suggests the presence of grey sands here. 2. Grey sands and sandstones (9.3 m). Chemical and petrological studies of the rocks conducted by G.V. Ivensen  show that the sands represent psammitic tuffs, and the sandstones, psammitic tuffites. 3. Greenish-grey clayey sand with lenticular interbeds of arenaceous limestones. Remains of vertebrates (reptiles, cynodonts, and amphibians) are present. Petrologically, the sand is psammitic tuffite. 4. Greenish-grey and dark-grey sandy clays (3 m) interbedded with light-grey sands containing freshwater fauna and rare fossils of vertebrates.