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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 ...
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.
Ichthyostegalia is an order of extinct amphibians, representing the earliest landliving vertebrates.The group is thus an evolutionary grade rather than a clade. [1] While the group are recognized as having feet rather than fins, most, if not all, had internal gills in adulthood and lived primarily as shallow water fish and spent minimal time on land.
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.
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.
Cartilaginous fish, class Chondrichthyes, consisting of sharks, rays and chimaeras, appeared by about 395 million years ago, in the middle Devonian. During the Late Devonian the first forests were taking shape on land. The first tetrapods appeared in the fossil record over a period, the beginning and end of which are marked with extinction events.
Suborder Feliformia (cat-like carnivorans and relatives) Family Nandiniidae (African palm civet) Family Prionodontidae (Asiatic linsangs) Family Felidae (domestic cats, leopards, lynxes, tigers, lions, cougars, and cat relatives) Family Viverridae (civets, African linsangs, and genets) Family Hyaenidae (hyenas and aardwolf)
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]