The first amniotes apparently arose in the Late Carboniferous. They descended from earlier <answer>reptiliomorph amphibious tetrapods</answer>, which lived on land that was already inhabited by insects and other invertebrates as well as by ferns, mosses and other plants. Within a few million years, two important amniote lineages became distinct: the synapsids, which would later include the common ancestor of the mammals; and the sauropsids, which would eventually come to include turtles, lizards, snakes, crocodilians, dinosaurs and birds. Synapsids have a single hole (temporal fenestra) low on each side of the skull.
From which group did amniotes descendents of?
reptiliomorph amphibious tetrapods