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However, most tetrapod species today are amniotes, most of which are terrestrial tetrapods whose branch evolved from earlier tetrapods early in the Late Carboniferous. The key innovation in amniotes over amphibians is the amnion , which enables the eggs to retain their aqueous contents on land, rather than needing to stay in water.
Several groups of tetrapods have undergone secondary aquatic adaptation, an evolutionary transition from being purely terrestrial to living at least part of the time in water. These animals are called "secondarily aquatic" because although their ancestors lived on land for hundreds of millions of years, they all originally descended from ...
Though stem-tetrapods originated in the preceding Devonian, it was in the earliest Carboniferous that the first crown tetrapods appeared, with full scaleless skin and five digits. During this time, amphibians (including many extinct groups unrelated to modern forms, referred to as "basal tetrapods") were the predominant tetrapods, and included ...
List of tetrapod families. Add languages ... This list does not include families that are extinct. ... Suborder Vombatiformes (koala, wombats, and multiple extinct ...
This change from a body plan for breathing and navigating in gravity-neutral water to a body plan with mechanisms enabling the animal to breath in air without dehydrating and move on land is one of the most profound evolutionary changes known. [18] [19] Tetrapods can be divided into four classes: amphibians, reptiles, birds and mammals.
The evolution of tetrapods began about 400 million years ago in the Devonian Period with the earliest tetrapods evolved from lobe-finned fishes. [1] Tetrapods (under the apomorphy-based definition used on this page) are categorized as animals in the biological superclass Tetrapoda, which includes all living and extinct amphibians, reptiles, birds, and mammals.
Primitive four-legged animals, the ancestors of Amphibians, Reptiles, Synapsids, birds, as part of Reptiles , and mammals, synapsids. For more information, see Tetrapod . Wikimedia Commons has media related to Tetrapoda .
Cylindrical centra (the main body of the vertebrae; cylindrical centra are also found in several groups of early tetrapods) Pedicellate teeth (the crowns of the teeth are separated from the roots by a zone of fibrous tissue; also found in some Dissorophoidea; the teeth of some fossil salamanders are not pedicellate)