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Thus, those very few tetrapod fossils found in this "gap" are all the more prized by palaeontologists because they document these significant changes and clarify their history. The transition from an aquatic, lobe-finned fish to an air-breathing amphibian was a significant and fundamental one in the evolutionary history of the vertebrates.
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 ...
It is included here to complete the transition of lobe-finned fishes to tetrapods, even though Pederpes is no longer a fish. By the late Devonian, land plants had stabilized freshwater habitats, allowing the first wetland ecosystems to develop, with increasingly complex food webs that afforded new opportunities.
The braincase of Ventastega has a mixture of fish-like and tetrapod-like characteristics, indicating that changes in the braincase during the fish-tetrapod transition occurred through a series of many small changes instead of one large change. [6]
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.
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.
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 ...
A notable characteristic that make a tetrapod's skull different from a fish's are the relative frontal and rear portion lengths. The fish had a long rear portion while the front was short; the orbital vacuities were thus located towards the anterior end. In the tetrapod, the front of the skull lengthened, positioning the orbits farther back on ...