A DEVONIAN TETRAPOD FROM NORTH-AMERICA

An early tetrapod fossil from the Upper Devonian of Pennsylvania (Cats kill Formation) extends the temporal range of tetrapods in North Ameri ca and suggests that they attained a virtually global equatorial distr ibution by the end of the Devonian. Derived features of the shoulder g irdle indicate that appendicular mechanisms of support and propulsion were well developed even in the earliest phases of tetrapod history. T he specialized morphology of the pectoral skeleton implies that the di versity of early tetrapods was great and is suggestive of innovative l ocomotor patterns in the first tetrapods.