Amniota

Reptilia

Sauropsida. Synapsida. Amniote. The first amniotes (referred to as "basal amniotes") resembled small lizards and evolved from the amphibian reptiliomorphs about 312 million years ago,[2] in the Carboniferous geologic period.

Their eggs could survive out of the water, allowing amniotes to branch out into drier environments. The eggs could also "breathe" and cope with wastes, allowing the eggs and the amniotes themselves to evolve into larger forms. The amniotic egg represents a critical divergence within the vertebrates, one enabled to reproduce on dry land—free of the need to return to water for reproduction as required of the amphibians. From this point the amniotes spread across the globe, eventually to become the dominant land vertebrates.