Closing the gaps in the origin of tetrapods

An increasing number of Late Devonian tetrapods have emerge from various localities and environments throughout the world. Just twenty years ago, all we knew of the transition of vertebrates from the water to land was the fossil Ichthyostega from Greenland. Today, 17 distinct Late Devonian tetrapod forms are known, including 9 named genera from 9 different individual localities worldwide. An article in press by Jennifer A. Clack, in Palaeogeography, Palaeoclimatology, Palaeoecology, nicely sums up all that we known of these new forms. One thing caught my attention in the article. Clack presents a novel idea concerning the way in which the first tetrapods may have walked on land. Previously, most people conjectured that early tetrapods medially-laterally "slittered" out of the water. But Clack, presents the idea that early tetrapods dorsally-ventrally "inch-wormed" out of the water based on the morphology of the vertebrate. Further investigation is required.


Jennifer A. Clack, The emergence of early tetrapods, Palaeogeography, Palaeoclimatology, Palaeoecology, In Press, Corrected Proof, Available online 8 September 2005.