Large dissorophoid skeletal elements from the Lower Permian Richards Spur Fissures, Oklahoma, and their paleoecological implications

Skeletal remains attributable to large dissorophoid amphibians, including f our femora, two humeri, and an isolated palatine bone, have recently been r ecovered from the Lower Permian fissure fill deposits at Richards Spur, Okl ahoma. Three of the femora are assignable to Acheloma cumminsi. One humerus represents an indeterminate trematopid, perhaps A, cumminsi, whereas the r emaining humerus and femur an evidently of dissorophid origin and probably assignable to Cacops. The palatine bone is of unusual morphology and eviden tly represents a third distinct large dissorophoid taxon. Although the Rich ards Spur faunal assemblage is unquestionably dominated by small animals su ch as Captorhinus aguti, Cardiocephalus, and Euryodus, the discovery of rar e, larger skeletal elements at the site implies that some elements of the f auna approached or slightly exceeded a body length of about one meter. Alth ough probably uncommon in the vicinity of the fissures, such larger species were clearly not excluded from the deposits by preservational biases. Like other taxa known from Richards Spur the dissorophoids were fully terrestri al as adults, and their presence reinforces previous interpretations of the Richards Spur paleoenvironment as an arid highland region. However, some R ichards Spur taxa have also been reported from lowland "deltaic" localities such as South Grandfield, Oklahoma. implying that their distribution was m ore cosmopolitan.