and Laurin around the turn of the millennium has greatly helped in pinpointing the transition. The early reptile-like amphibians were mostly aquatic, the first highly terrestrially adapted groups being the Seymouriamorpha and the Diadectomorpha. The seymouriamorphs were small to medium-sized animals with stout limbs, their remains are sometimes found in what has been interpreted as dry environments, indicating their skin had a water-tight epidermal horny overlay or even scales as evident in Discosauriscus. Their skeletons are very similar to those of early reptiles, though finds of seymouriamorph tadpoles have shown they retained an amphibian reproduction. The diadectomorph families are generally considered to be the closest known relatives of modern amniotes. They too are thought to have been on the amphibian side of the divide, despite no known diadectomorph fossil tadpoles. Analysis of new finds and composition of larger trees do however indicate the phylogeny may not be as well understood as traditionally thought. Several authors have suggested that terrestrial eggs evolved from amphibian eggs laid on land to avoid predation on the eggs and competition from other labyrinthodonts. The amniote egg would necessarily have had to evolve from one with an anamniote structure, as those found in fish and modern amphibians. In order for such an egg to excrete CO2 on land without the specialized membranes to aid in respiration, it would have to be very small, 1 cm in diameter or smaller. Such very small eggs with direct development would severely restrict the adult size, thus the amniotes would have evolved from very small animals. A number of small, fragmentary fossils of possibly diadectomorph affinity has been proposed as the first amniote, including Gephyrostegus, Solenodonsaurus, Westlothiana and Casineria. Fossilized footprints found in New Brunswick indicate the first reptiles were established by 315 million years ago. History of classification The term labyrinthodont was coined by Hermann Burmeister in reference to the tooth structure. Labyrinthodontia was first used as a systematic term by Richard Owen in 1860, and assigned to Amphibia the following year. It was ranked as an order under class Amphibia by Watson in 1920 and as a superorder by Romer in 1947. An alternative name, Stegocephalia was created in 1868 by American palaentologist Edward Drinker Cope, from Greek stego cephalia—"roofed head", and refer to anapsid skull and the copious amounts of dermal armour some of the larger forms evidently had. This term is widely used in 19th and