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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 Python reticulatus.. 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 extending to the ...
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.
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 ...
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]
Pythons and boas—primitive groups among modern snakes—have vestigial hind limbs: tiny, clawed digits known as anal spurs, which are used to grasp during mating. [26]: 11 [28] The families Leptotyphlopidae and Typhlopidae also possess remnants of the pelvic girdle, appearing as horny projections when visible.
In the case of limb loss during evolution, vestigial structures testify to this change (remains of the pelvis, rudimentary femur or spurs in boas, pythons and Typhlops). The evolutionary process of transforming quadrupedal lizards into legless forms results in three main characteristics: the regression of the limbs is carried out gradually, via ...
[10]: 11 [11] Pythons and boas—primitive groups among modern snakes—have vestigial hind limbs: tiny, clawed digits known as anal spurs, which are used to grasp during mating. [10]: 11 [12] The Leptotyphlopidae and Typhlopidae groups also possess remnants of the pelvic girdle, sometimes appearing as horny projections when visible.