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Acanthostega (meaning "spiny roof" in Ancient Greek) is an extinct genus of stem-tetrapod, among the first vertebrate animals to have recognizable limbs.It appeared in the late Devonian period (Famennian age) about 365 million years ago, and was anatomically intermediate between lobe-finned fishes and those that were fully capable of coming onto land.
Evolutionary theory says all animals that are walking on land actually evolved from sea-dwelling creatures at some point in the ancient past. To study this further, scientists from McGill ...
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.
This animal is noticeable from its larger size (exceeded only by the elephant seals), nearly hairless skin, flattened snout and long upper canines, known as tusks. Like otariids, walruses can walk on land with their hind limbs. When moving in water, the walrus relies on its hind limbs for locomotion, while its forelimbs are used for steering.
Land and avian animals. List of prehistoric amphibian genera; List of prehistoric mammals; ... This page was last edited on 3 January 2025, at 18:11 (UTC).
These fish use a range of methods for land movement, such as lateral undulation, tripod-like walking (using paired fins and tail), and jumping. Many of these methods of locomotion incorporate multiple combinations of pectoral-, pelvic-, and tail-fin movement. Many ancient fish had lung-like organs, and a few, such as the lungfish and bichir ...
Despite eurypterids clearly being primarily aquatic animals that almost certainly evolved underwater (some eurypterids, such as the pterygotids, would even have been physically unable to walk on land), it is unlikely the "gill tract" contained functional gills when comparing the organ to gills in other invertebrates and even fish.
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