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Sarcopterygii (/ ˌ s ɑːr k ɒ p t ə ˈ r ɪ dʒ i. aɪ /; from Ancient Greek σάρξ (sárx) 'flesh' and πτέρυξ (ptérux) 'wing, fin') — sometimes considered synonymous with Crossopterygii (from Ancient Greek κροσσός (krossós) 'fringe') — is a clade (traditionally a class or subclass) of vertebrate animals which includes a group of bony fish commonly referred to as lobe ...
The first lobe-finned fish, found in the uppermost Silurian (c. 418 Mya), closely resembled spiny sharks, which became extinct at the end of the Paleozoic. In the Early to Middle Devonian (416–385 Mya), while the predatory placoderms dominated the seas, some lobe-finned fish came into freshwater habitats.
They evolved from lobe-finned fish of the clade Sarcopterygii, appearing in coastal water in the middle Devonian, and giving rise to the first amphibians. [ 59 ] 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 ...
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. [20] These ancient lobe-finned fish had evolved multi-jointed leg-like fins with digits that enabled them to crawl along the sea bottom.
Coelacanth. Coelacanths (/ ˈsiːləkænθ / ⓘ SEE-lə-kanth) (order Coelacanthiformes) are an ancient group of lobe-finned fish (Sarcopterygii) in the class Actinistia. [2][3] As sarcopterygians, they are more closely related to lungfish and tetrapods (which includes amphibians, reptiles, birds and mammals) than to ray-finned fish.
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 more extreme version found in early tetrapods is known as "labyrinthodont" or "labyrinthodont plicidentine". This type of tooth structure has evolved independently in several types of bony fishes, both ray-finned and lobe finned, some modern lizards, and in a number of tetrapodomorph fishes.
"Labyrinthodont"-grade vertebrates evolved from lobe-finned fishes in the Devonian, though a formal boundary between fish and amphibian is difficult to define at this point in time. "Labyrinthodont" generally refers to extinct four-limbed tetrapods with a large body size and a crocodile-like lifestyle.