Fossil range: 360 Ma Late Devonian
Hynerpeton ("creeping animal (herpeton) from Hyner") was a basal carnivorous tetrapod that lived in the lakes and estuaries of the Late Devonian period around 360 million years ago. Like many primitive tetrapods, it is sometimes referred to as an "amphibian", though it is not a true member of the class Amphibia. The Late Devonian saw the evolution of plants into trees and growing into vast forests pumping oxygen into the air, possibly giving Hynerpeton an edge because it evolved complex lungs to exploit it. Its lungs probably consisted of sacs like modern terrestrial vertebrates. Only a few bones have been found from Hynerpeton, in Red Hill, Pennsylvania, U.S.A.. The known fossils include two shoulder girdles, two lower jaws, a jugal bone and some gastralia.
The structure of the shoulder girdle indicates this animal may have been one of the earlier, more primitive tetrapods to evolve during the Devonian. Information on the relationship of the known fossils of Hynerpeton to other Devonian tetrapods can be found in Gaining Ground The Origin and Evolution of Tetrapods by J.A. Clack.
It is thought that that these early amphibians are descended from lobe-finned fish, such as Hyneria, whose stout fins evolved into legs and their swim bladder into lungs. It is still not known whether Hynerpeton is the direct ancestor to all later backboned land animals (including humans), but the fact that it had eight fingers, not five, suggests that it is simply our evolutionary cousin.
In popular culture
Hynerpeton is featured in the first episode of the 2005 documentary series Walking With Monsters. It was seen fancifully and erroneously evolving from Cephalaspis, and then walking on land. One of the Hynerpeton meets a gruesome end when a predatory Hyneria fish ambushes it at the water's edge, shortly after a mating session with a female Hynerpeton.
Tim Haines, and Paul Chambers. The Complete Guide to Prehistoric Life. Pg. 30-31. Canada: Firefly Books Ltd., 2006