Carboniferous

The Carboniferous was a geologic period from 358.9 mya (the Devonian period) to 298 mya (the Permian period).  During this time there were massive coal swamps that covered most of the planet.  The animal life of this time was changing drastically.  Enormous insects like Meganeura and Arthropleura was carnivores on land while the giant amphibians like Eogyrinus ruled the waters.  This was also the period of the first reptiles.  The Amniotes are all reptiles, birds, and mammals.  The very first Amniotes of the Carboniferous were Paleothyris and Protoclepsydrops.