Squatina is represented by complete skeletons in Germany's Late Jurassic (S. acanthoderma, FRAAS 1854). In most cases, it is only the teeth of this genus that leave a record through the Mesozoic and Cenozoic. Squatina teeth are extremely hard to seperate into species. Most fossil species are defined by geologic age and not by differences in the teeth. Modern species are often differentiated by color patterns, dorsal spines, barbels or other minor external variations. The teeth are similar in both jaws and vary only slightly with jaw position.