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The first major groups of amphibians developed in the Devonian period, around 370 million years ago, from lobe-finned fish which were similar to the modern coelacanth and lungfish. [21] These ancient lobe-finned fish had evolved multi-jointed leg-like fins with digits that enabled them to crawl along the sea bottom.
The resemblance between the crocodilians and phytosaurs in particular is quite striking; even to the point of having evolved the graduation between narrow- and broad-snouted forms, due to differences in diet between particular species in both groups. [88] Death adders strongly resemble true vipers, but are elapids. [89]
Modern amphibians, which evolved from earlier groups, are generally semiaquatic; the first stages of their lives are as waterborne eggs and fish-like larvae known as tadpoles, and later undergo metamorphosis to grow limbs and become partly terrestrial and partly aquatic.
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 Devonian saw the demise of virtually all jawless fish, save for lampreys and hagfish, as well as the Placodermi, a group of armoured fish that dominated much of the late Silurian, and the rise of the first labyrinthodonts, transitional between fish and amphibians. [10]
Tiktaalik, a transitional form between tetrapodomorph fish and labyrinthodonts, combining fishlike fins with a pectoral girdle separate from the skull. The labyrinthodonts have their origin in the early middle Devonian (398–392 Mya) or possibly earlier. They evolved from a bony fish group: the fleshy-finned Rhipidistia.
Mixing just as well with similar-sized fish as they do with their own species, these fully aquatic additions can reach up to 6.4 cm in size and live for five to seven years on average.
Eusthenopteron (from Greek: εὖ eû, 'good', Greek: σθένος sthénos, 'strength', and Greek: πτερόν pteron 'wing' or 'fin') [2] is a genus of prehistoric sarcopterygian (often called "lobe-finned") fish known from several species that lived during the Late Devonian period, about 385 million years ago.