Histology of Dvinosaurus campbelli (Temnospondyli, Dvinosauria) from the Late Permian Locality Gorokhovets, Vladimir Region

This study describes the microanatomical and histological structure of the femur and hypocentra of the neotenic temnospondyl amphibian Dvinosaurus campbelli from the Late Permian locality Gorokhovets, Vladimir Region (Upper Vyatkian Substage, subzone Chroniosuchus paradoxus of the Scutosaurus karpinskii zone). The femur of D. campbelli is characterized by a “pachyosteous” structure (dense thick periosteal cortex in the diaphysis) and a large number of growth marks (about 57); the hypocentrum has an “osteoporotic” structure. The neotenic nature of D. campbelli is confirmed by the presence of unresorbed cartilage in the skeletal elements of large-sized forms. Microanatomical and morphological features indicate that D. campbelli was an ambush feeder (using concealment during hunting).