SARCOPTERYGIAN APPENDAGES ON LATE DEVONIAN FLOODPLAINS

Late Devonian freshwater ecosystems contained a diversity of sarcopterygian fish and early tetrapods that specialized for diverse modes of locomotion. Much of this diversity is seen in the design of their appendages. Appendages vary in size, shape, extent of the dermal skeleton, number of endochondral elements and in the kinds of joints that allow movements between neighboring bones. The result of this diversity is a suite of appendages that function as paddles and props, some of which are able to guide movements over complex substrates. The adaptive radiation of appendage design also witnesses the parallel evolution of similar designs in different lineages. This kind of evolution is informative of both the functional and developmental factors that underlie limb variation. The variations of appendage design reflect the diversity of new ecological opportunities that were available to sarcopterygians in the evolving ecosystems of Late Devonian floodplains.