Their heads were flat and massive, with a host of labyrinthodont teeth. Ichthyostegidae is a small family of extinct labyrinthodont amphibian from the Devonian. The term "labyrinthodont" was coined by Hermann Burmeister in reference to the tooth structure. Tadpole remains with telltale external gills are also known from several labyrinthodont groups. The skull was flat with dorsally placed eyes and armed with large labyrinthodont teeth. The more extreme version found in early tetrapods is known as "labyrinthodont" or "labyrinthodont plicidentine". The South Polar region also was home to the last labyrinthodont amphibian, "Koolasuchus". Animals inhabiting the coal forests were invertebrates (particularly insects), fish, labyrinthodont amphibians, and early reptiles. Its teeth were conical and labyrinthodont, with infolding of enamel and dentin. Early in the 20th century the sixth labyrinthodont amphibian discovery was made somewhere in Kansas. Baphetids were large labyrinthodont predators of the Late Carboniferous period (Namurian through Westphalian) of Europe.