a group of Late Permian fossil amphibians and reptiles that lived west of the Urals.
The Severnaia Dvina fauna was discovered in the late 19th century by the Russian paleontologist V. P. Amalitskii on the Malaia Severnaia Dvina River near the city of Kotlas. After many years of excavation more than 20 skeletons, dozens of skulls, and thousands of individual bones were discovered. The finds, which constitute one of the world’s best collections of ancient terrestrial vertebrates, are housed at the Museum of the Paleontological Institute of the Academy of Sciences of the USSR. The fauna has been studied by several Russian scientists, including P. P. Sushkin, A. P. Bystrov, and A. P. Gart-man-Veinberg.
Most of the Severnaia Dvina fauna accumulated in river deltas. The skeletal remains very frequently form the nucleus of concretions in dense sandstone that possibly formed around the decomposing remains of the animals. Most of the fossils belong to the Pareiasauria (genus Skutosaurus)—a suborder of herbivorous reptiles. The others belong to various groups of Theromorpha: predatory mammal-toothed reptiles included Inostrancevia and Dvinia, and herbivores included dicynodonts. Amphibian remains include Kotlassia (which resembled reptiles in a number of anatomic characteristics) and Dvinosaurus (a neotenic labyrinthodont).
Study of the Severnaia Dvina fauna is important in the identification of the early evolutionary stages of reptiles and mammals and in the stratigraphic analysis of the continental beds of the Upper Paleozoic.
A. K. ROZHDESTVENSKII