Eryops megacephalus (Cope 1877; AMNH 4189; Permian, 280 mya; up to 3m in length, 60 cm skull) was derived from a sister to Sclerocephalus. It retained the broad overlapping ribs of earlier tetrapods, but had stronger limbs and elevated nares.
Edops craigi (Romer and Witter 1942; Early Permian; 2m in length) Edopoids also had particularly big premaxillae (the bones that form the tip of the snout) and proportionally small external nostrils.
Cope ED 1877. Descriptions of extinct Vertebrata from the Permian and Triassic formations of the United States. Proceedings of the American Philosophical Society 17(100):182-193.
Lloyd G 1850. On a new species of Labyrinthodon from the New Red Sandstone of Warwickshire. Report of the British Association for the Advancement of Science 19:56–57.
Romer AS and Witter RV 1942. Edops, a primitive rhachitomous amphibian from the Texas Red Beds. The Journal of Geology 50(8):925–960.
Schoch RR 1997. Cranial anatomy of the Permian temnospondyl amphibian Zatrachys serratus Cope 1878, and the phylogenetic position of the Zatrachydidae. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen. 206 (2): 223–248.
Urban M and Berman DS 2007. First occurrence of the late Paleozoic amphibian Zatrachys serratus (Temnospondyli, Zatrachydidae) in the eastern United States. Annals of Carnegie Museum. 76 (3): 157–164.
