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By the Upper Devonian period, the fin-limb transition as well as other skeletal changes such as gill arch reduction, opercular series loss, mid-line fin loss, and scale reduction were already completed in many aquatic organisms. [3] As aquatic tetrapods began their transition to land, several skeletal changes are thought to have occurred to ...
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 ...
Tulerpeton is one of the early transition tetrapods – a marine animal capable of living on land. The separation of the pectoral-shoulder girdle from the head allowed the head to move up and down, and the strengthening of the legs and arms allowed the early tetrapods to propel themselves on land. Tulerpeton is important in the study of dactyly.
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 vertebrate land invasion refers to the transition of vertebrate animals from being aquatic/semiaquatic to predominantly terrestrial during the Late Devonian period. This transition allowed some vertebrates to escape competitive pressure from other aquatic animals and explore niches on land, [1] which eventually established the vertebrates as the dominant terrestrial phylum.
[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 ...
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.
As biodiversity has grown, so has the number of species and the number of niches that tetrapods have occupied. The first tetrapods were aquatic and fed primarily on fish. Today, the Earth supports a great diversity of tetrapods that live in many habitats and subsist on a variety of diets. [24]