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Therefore, Panderichthys can only be a "late-surviving relic", [14] showing traits that evolved during the transition from fish-like creatures to tetrapods, but whose date does not reflect that transition. The tracks "force a radical reassessment of the timing, ecology and environmental setting of the fish–tetrapod transition, as well as the ...
Ichthyostega (from Greek: ἰχθῦς ikhthûs, 'fish' and Greek: στέγη stégē, 'roof') is an extinct genus of limbed tetrapodomorphs from the Late Devonian of what is now Greenland. It was among the earliest four-limbed vertebrates ever in the fossil record and was one of the first with weight-bearing adaptations for terrestrial locomotion.
As aquatic tetrapods began their transition to land, several skeletal changes are thought to have occurred to allow for movement and respiration on land. Some adaptations required to adjust to non-aquatic life include the movement and use of alternating limbs, the use of pelvic appendages as sturdy propulsors, and the use of a solid surface at ...
At any rate, it demonstrates that the fish–tetrapod transition was accompanied by significant character incongruence in functionally important structures.". [70] p. 638. From the end of the Devonian to the Mid Carboniferous a 30 million year gap occurs in the fossil record.
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 period (419–359 Mya), also known as the Age of Fishes, saw the development of early sharks, armoured placoderms and various lobe-finned fish, including the tetrapod transitional species. The evolution of fish began about 530 million years ago during the Cambrian explosion.
Tetrapodomorpha (also known as Choanata [3]) is a clade of vertebrates consisting of tetrapods (four-limbed vertebrates) and their closest sarcopterygian relatives that are more closely related to living tetrapods than to living lungfish.
In most analyses, the group as traditionally imagined is actually an evolutionary grade, the last "fishes" of the tetrapod stem line, though Chang and Yu (1997) treated them as the sister clade to Tetrapoda. [15] [16] Elpistostegalia was re-defined as a clade containing Panderichthys and tetrapods. [7] Below is a cladogram from Swartz, 2012. [7]