The Freakiest of October CARBONIFEROUS Reptiles

The most important trait that distinguishes reptiles from amphibians is their reproductive system: the shelled eggs of reptiles are better able to withstand dry conditions, and thus don't need to be laid in water or moist ground. The evolution of reptiles was spurred by the increasingly cold, dry climate of the late Carboniferous period; one of the earliest reptiles yet identified, Hylonomus, appeared about 315 million years ago, and the giant (almost 10 feet long) Ophiacodon only a few million years later. By the end of the Carboniferous, reptiles had migrated well toward the interior of Pangea; these early pioneers went on to spawn the archosaurs, pelycosaurs and therapsids of the ensuing Permian period (and the archosaurs then went on to spawn the first dinosaurs).