Fossil Profile: Eoplacophis

Placophida ancestrally comprised a clade of arboreally adapted acripod placoderms. Though they were ancestrally semi-aquatic burrowers with robust digging forelimbs at first, the group that gave rise to shellsnakes found them useful for ascending trees as well. Shellsnakes would have ancestrally climbed using these arms, but this method of movement has gone out of fashion. Most extant shell snakes either strangle branches with their bodies, undulate the scales of their belly, or in the most derived iactocauds, grew a pair of limbs from their claspers. Such groups use their forlimbs to aid prey capture instead. Eoplacophis is the earliest representative of a shellsnake which did so. Despite its basal body plan, its discovery in the late Apauovian, Dome 4's chronological equivilent of the Permian, makes it a surprisingly young taxon and would have co-existed with the earliest true shlugs if the molecular clock is to be believed.