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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.
The group of lobe-finned fishes that were the ancestors of the tetrapod are grouped together as the Rhipidistia, [60] and the first tetrapods evolved from these fish over the relatively short timespan 385–360 Ma. The early tetrapod groups themselves are grouped as Labyrinthodontia.
Tulerpeton is one of the early transition tetrapods – a marine animal capable of living on land. The separation of the pectoral-shoulder girdle from the head allowed the head to move up and down, and the strengthening of the legs and arms allowed the early tetrapods to propel themselves on land. Tulerpeton is important in the study of dactyly.
Other factors that caused aquatic tetrapods to spend more time on land caused the development of terrestrial hearing with the development of a tympanum within an otic notch and developed by convergent evolution at least three times. [10] There was also a change in the dermal bones of the skull in the aquatic tetrapods. [5]
It thrived as a top predator 40 million years before dinosaurs evolved to roam the Earth, according to the study. The most complete Gaiasia jennyae skeleton includes a well-preserved skull and ...
Westlothiana ("animal from West Lothian") is a genus of reptile-like tetrapod that lived about 338 million years ago during the latest part of the Viséan age of the Carboniferous. The genus is known from a single species, Westlothiana lizziae. It is the oldest known uncontroversial tetrapod, closely related to but not an amniote. [1]
The ancestors of true amniotes, such as Casineria kiddi, which lived about 340 million years ago, evolved from amphibian reptiliomorphs and resembled small lizards. At the late Devonian mass extinction (360 million years ago), all known tetrapods were essentially
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.