Most of the species in the class what lay amniotic eggs?

Amniotic eggs, an evolutionary innovation that helped tetrapods more "advanced" than amphibians adapt to a fully terrestrial lifestyle, are an adaption utilized by most reptiles, with some live-bearing Snakes retaining the eggs inside the body until they hatch, though there are also Boas that are actually viviparous like most mammals. All Birds also lay amniotic eggs, as do Monotremes, a "primitive" order of mammals which consist of the Platypus and Echidna. Hope this helps! :) xxx