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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 ...
Several groups of tetrapods have undergone secondary aquatic adaptation, an evolutionary transition from being purely terrestrial to living at least part of the time in water. These animals are called "secondarily aquatic" because although their ancestors lived on land for hundreds of millions of years, they all originally descended from ...
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.
Ichthyostega was a fairly large animal for its time, as it was broadly built and about 1.5 m (4.9 ft) long. The skull was low, with dorsally placed eyes and large labyrinthodont teeth. The posterior margin of the skull formed an operculum covering the gills.
Jennifer Alice Clack, FRS, FLS (née Agnew; 3 November 1947 – 26 March 2020) was an English palaeontologist and evolutionary biologist.She specialised in the early evolution of tetrapods, specifically studying the "fish to tetrapod" transition: the origin, evolutionary development and radiation of early tetrapods and their relatives among the lobe-finned fishes.
[18] [19] Tetrapods can be divided into four classes: amphibians, reptiles, birds and mammals. Marine tetrapods are tetrapods that returned from land back to the sea again. The first returns to the ocean may have occurred as early as the Carboniferous Period [ 20 ] whereas other returns occurred as recently as the Cenozoic , as in cetaceans ...
The tetrapods evolved from the lobe-finned fishes about 395 million years ago in the Devonian. [23] The specific aquatic ancestors of the tetrapods, and the process by which land colonization occurred, remain unclear, and are areas of active research and debate among palaeontologists at present.
Dozens of captive animal species have been found infected or proven able to be experimentally infected with SARS-CoV-2, the virus that causes COVID-19. The virus has also been found in over a dozen wild animal species. Most animal species that can get the virus have not been proven to be able to spread it back to humans.