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Pelvic spur. Pelvic spurs (also known as vestigial legs) are external protrusions found around the cloaca in certain superfamilies of snakes belonging to the greater infraorder Alethinophidia. [1] These spurs are made up of the remnants of the femur bone, which is then covered by a corneal spur, or claw-like structure. [1]
The skull of a snake is a very complex structure, with numerous joints to allow the snake to swallow prey far larger than its head. The typical snake skull has a solidly ossified braincase, with the separate frontal bones and the united parietal bones extending downward to the basisphenoid, which is large and extends forward into a rostrum ...
Eupodophis. Eupodophis is an extinct genus of snake from the Late Cretaceous period. It has two small hind legs and is considered a transitional form between Cretaceous lizards and limbless snakes. The feature, described as vestigial, was most likely useless to Eupodophis. [1] The type species Eupodophis descouensi was named in 2000 and resides ...
Snakes originated about 120 million years ago. Early snakes had vestigial limbs, with the oldest-known fully limbless snake living around 85 million years ago, according to George Washington ...
The term spur is sometimes used to describe the pelvic spur, vestigial limbs found in primitive snakes, such as boas and pythons and in the striped legless lizard. [3] [4] The spurs primarily serve as holdfasts during mating. As these form at the terminal end of the limb, they may properly be claws rather than true spurs.
More advanced snakes have no remnants of limbs, but basal snakes such as pythons and boas do have traces of highly reduced, vestigial hind limbs. Python embryos even have fully developed hind limb buds, but their later development is stopped by the DNA mutations in the ZRS.
Vestigiality. In humans, the vermiform appendix is sometimes called a vestigial structure as it has lost much of its ancestral digestive function. Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. [1]
Ophidia / oʊˈfɪdiə / (also known as Pan-Serpentes[2]) is a group of squamate reptiles including modern snakes and reptiles more closely related to snakes than to other living groups of lizards. Ophidia was defined as the "most recent common ancestor of Pachyrhachis and Serpentes (modern snakes), and all its descendants" by Lee and Caldwell ...