This chapter examines the origins of lissamphibia and amniota. It provides an overview of Paleozoic tetrapods, which includes the taxa on the divergence and diversification of lissamphibians and amniotes. Evolutionary changes in skulls, vertebrae, limb girdles, limbs, and ankles have enabled the tracking of the diversification of Paleozoic tetrapods and the interpretation of aspects of their biology. Meanwhile, the evolution of the amniotic egg in the Carboniferous has allowed amniotes to escape their dependence on water for reproduction. The chapter details the characteristics of amniotes that allowed for greater independence from moist habitats and the ability to grow very large. It explains how studying fossils can result in a greater understanding of the biology, ecology, and functional morphology of amniotes and their subsequent diversification.
