- any member of several orders of small to large lizardlike terrestrial and freshwater amphibians, some ancestral to land vertebrates, forming the extinct subclass Labyrinthodonta that flourished from the Devonian through the Triassic periods, characterized by a solid, flattened skull and conical teeth.
- having teeth with complexly infolded enamel surfaces.
- belonging to or pertaining to the Labyrinthodonta.
- any primitive amphibian of the order Labyrinthodontia, of late Devonian to Triassic times, having teeth with much-folded dentine
- Any of various extinct amphibians of the group Labyrinthodontia, which were the dominant animals of the late Paleozoic Era. Labyrinthodonts had stocky, lizardlike bodies with short limbs, and fishlike teeth with labyrinthine structure (with complex infolding of the enamel). They varied from the size of a salamander to that of a crocodile. One early genus, Ichthyostega, was probably the first terrestrial vertebrate.