YAKUTSK, March 11. /TASS/. A group of scientists plans an expedition to the polar site of the dinosaur fauna in Yakutia's Suntarsky District to discover new remains of dinosaurs and other Mesozoic animals, as well as to find data on the adaptation of those animals to circumpolar conditions, Pyotr Kolosov, a chief researcher at the Institute of Diamond and Precious Metals Geology of the Russian Academy of Sciences' Siberian Branch, told TASS.
Remains of dinosaurs and related vertebrates (dinosaur fauna) that lived in the polar latitudes in the Mesozoic era have been found only at a few locations across the world. The only dinosaur site of the Early Cretaceous age in the Northern Hemisphere is the area of the Teete Creek in the Vilyui River basin in Yakutia. This remote area is some 100 km from the village of Horo.
"A group of scientists from the St. Petersburg State University and the Zoological Institute of the Russian Academy of Sciences is planning an expedition this summer. Further studies of the Teete site will make it possible to describe new taxa (groups of one or more populations of an organism or organisms - TASS) of dinosaurs and other Mesozoic vertebrates, as well as to obtain new data on the adaptation of those animals to circumpolar conditions," the scientist said.
According to him, the researchers will search for reasons of the animals' extinction. "Our institute keeps the data showing that volcanic activity was the cause of both the survival and extinction of dinosaurs: due to powerful volcanic eruptions, dust emissions, the vegetation must have gradually disappeared. The vegetation was the food base of herbivorous dinosaurs and thus they died. Predatory dinosaurs also lacked food," the scientist noted.
Earlier expeditions
In 1988, as well as in 2002-2012, Kolosov managed searches for dinosaur fauna in the Suntarsky District. The expeditions featured local residents and school students. They rode horses to the excavation site - through the taiga, swamps and streams.
The participants in those expeditions managed to find large skeletal elements and teeth of various groups of dinosaurs. They also found fragmentary bone elements (vertebrae, limb bones, jaws) of salamanders, choristodera, lizards. The finds of vertebrate remains in the deposits of the Early Cretaceous in Yakutia added another location to the polar areas where those animals had lived.
In 2017-2019, scientists from St. Petersburg conducted comprehensive paleontological studies at Teete. In addition to vertebrates' remains, they found bones of mammaliformes (a group of organisms including mammals and their closest extinct relatives) and mammals. "In the study of the discovered vertebrate remains, we described new genera of Mesozoic mammaliformes, mammals and salamanders. The presence of stem salamanders, basal turtles and other Jurassic vertebrates in the Teete Early Cretaceous fauna vertebrates indicates that that territory was a refugium (an area where a species or group of species survived or are experiencing an unfavorable period of geological time for them, during which these life forms were disappearing over large areas - TASS) for Jurassic relics," the expert said.
"Judging by the available finds, in Teete used to live predatory dinosaurs, but their relationships have not been determined yet, and the herbivorous forms were represented mainly by stegosaurs, as well as by rarer sauropods. The findings of 12 sauropod teeth make Teete the northernmost location of sauropods," the scientist noted.
The unique discovery in Teete of a tooth of a very young, probably newborn, sauropod, for the first time indicates that those lizards could breed in high latitudes. The find allows scientists to suggest the dinosaurs living there did not migrate to reproduce, but lived in those latitudes year-round.
Polar dinosaurs
The conducted research has significantly expanded the fauna composition at the Teete site. Scientists have identified new taxa of salamanders, mammaliamorphs and mammals. The presence of the mammalian genus Gobiconodon confirms the hypothesis that genus had spread from Asia to North America by Beringia.
"At the beginning of the Cretaceous period, like it was also in the Jurassic, there were two huge supercontinents on the Earth: the northern one - Laurasia, which united North America, Europe, Asia and the northern part of China. Significant parts of Laurasia in the Northern Hemisphere in the Early Cretaceous epoch were elevated lands. Dinosaurs crossed into North America by land, not through the Bering Strait. Unlike ichthyosaurs, dinosaurs are land animals," the scientist said.
The Teete fauna composition has turned out to be atypical for the Cretaceous period and indicates that there used to live relict species more characteristic of the Jurassic period. The presence of Cretaceous relict vertebrates in Teete and in the Lower Cretaceous localities of Western Siberia also indicates that there were no significant differences between high-latitude (Yakutia) and moderate-latitude (Western Siberia) vertebrate complexes.
"Thus, the transition between the Jurassic and the Early Cretaceous biotas in Northern Asia was gradual. Despite the conducted research, the Teete vertebrate complex has not exhausted its scientific potential and requires further study. In future exploration, new materials on salamanders, lizards, dinosaurs and mammals may be discovered. Additional materials will be used to describe new genera and species of choristodera, dinosaurs," the scientist said in conclusion.