The labyrithodonts were some of the dominant animals from the Devonian to the Lower Triassic (about 390 to 210 million years ago).
The group is an evolutionary grade (a polyphyletic or paraphyletic group) of species which look rather similar.
The name describes the pattern of infolding of the dentine and enamel of the teeth, which often fossilise.
They are also have a heavily armoured skull roof (so they also have an even older name “Stegocephalia”), and complex vertebrae.
0.4 inch excellent tiny claw. Complete.