a subclass of extinct reptiles of the late Carboniferous to middle Jurassic periods. They were the most widely distributed and best-adapted land vertebrates of the late Paleozoic era. Most of the Synapsida were predators, although there were also herbivorous members. It is possible that the higher Synapsida were warm blooded. Numerous remains have been found on all continents except Australia. In the USSR fossils have been found in the northern European part in the Northern Dvina, Middle Volga, and Ural regions. The subclass comprises two orders, Pelycosauria and Therapsida, with about 60families. They are important in explaining the evolution of the higher vertebrates.
A. K. ROZHDESTVENSKII