by Alexei HERMAN, Dr. Sc. (Geol. & Min.), Geological Institute, Russian Academy of Sciences
What natural conditions did dinosaurs live in? Numerous remains of these reptiles were found in the regions with a tropical or subtropical climate and weak seasonality in the Mesozoic (251 - 65 Ma). That is why discovery of remains in the Arctic Regions--Chukotka and Alaska-interested paleontologists and generated a number of hypotheses explaining how this has become possible.
MYSTERIES OF THE CRETACEOUS
In 1961, US geologist Robert Liscomb found a multitude of dinosaur bones in the northern part of Alaska (70 °N) that he originally took for remains of not very ancient Cenozoic* mammals. Only in the mid-1980s an exceptional value of this discovery became clear: the bones turned out to be bones of dinosaurs that inhabited the Arctic Regions long ago, at the end of the Cretaceous**. Further paleontological excavations were carried out in this region by American paleontologists Anthony Fiorillo, Roland Gangloff and their associates who found thousands of bones for several years. These research works gave rise to disputes on the ecology of discovered animals: were they permanent residents of the Arctic Regions or migrated to the south in winter? What did they eat? How and at what speed did they move?
By now, at the site located in the low reaches of the Colville River in the Ocean Point area named the Liscomb Quarry after its discoverer, remains of cartilaginous and bony fish, Hesperornis birds, multituberculate, marsupial and placental mammals, dinosaurs--small and big theropods (carnivors from the Dromaeosaurus, Saurornitholestes, Troodon genera and tyrannosaurids
* The Cenozoic--a period in geological history that started about 65 mln years ago and lasts till now.--Ed.
** The Cretaceous--the latest period of the Mesozoic; began 145 mln years ago, lasted for 80 mln years.--Ed.
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