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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.
As early tetrapods are found on two Devonian continents, Laurussia and Gondwana, as well as the island of North China, it is widely supposed that early tetrapods were capable of swimming across the shallow (and relatively narrow) continental-shelf seas that separated these landmasses. [38] [39] [40]
The trackways are late Middle Devonian in age based on a palynological assemblage from the Valentia Slate Formation and the U-Pb radioisotopic dating of an interstratified air-fall tuff bed to ca. 385 Ma, [3] making these tetrapod trackways some of the earliest recorded, along with traces of early Middle Devonian (Eifelian) age from Poland. [4]
The Zachelmie trackways are a series of Middle Devonian-age trace fossils in Poland, purportedly the oldest evidence of terrestrial vertebrates in the fossil record.These trackways were discovered in the Wojciechowice Formation, an Eifelian-age carbonate unit exposed in the Zachełmie Quarry of the Świętokrzyskie Mountains (Holy Cross Mountains).
Tulerpeton is an extinct genus of Devonian four-limbed vertebrate, known from a fossil that was found in the Tula Region of Russia at a site named Andreyevka. This genus and the closely related Acanthostega and Ichthyostega represent the earliest tetrapods.
The creature's name comes from the Gai-As rock formation in Namibia where the fossils were found and for the late paleontologist Jennifer Clack, who studied how tetrapods evolved.
The earliest ones, the stem tetrapods, spawned evolutionary lineages that led to true amphibians, reptiles and mammals. While this was taking place, some stem tetrapods persisted, especially in ...
Transitional forms prior to fully developed terrestrial tetrapods such as Acanthostega, are thought to have captured prey in the water. [13] Large coronoid fangs are present in the fishes Eusthenopteron, Panderichthys, and Tiktaalik, and the early tetrapod, Ventasega. In Acanthostega, which is more derived, the large teeth are absent.