A neoplasm in cranial bone of an early Triassic amphibian has been investigated. Although no tissue has survived, the cranial flat bone is similar to that in living animals of the same class. Evidence is presented in support of a hypothesis that the neoplasm is a skeletal tumor which consists of non-functional bone and looks like an atypical tumorous bone of skeletal origin. It was identified as a parostotic osteosarcoma on the basis of macro- and microscopic and X-ray examination.