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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 ]
[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.
Anilios endoterus is a terrestrial subterranean species of burrowing snake that has a worm-like appearance. [6] Like many other snakes in the Typhlopidae family, the eyes of the interior blind snake are vestigial and appear like small, dark eye-spots under the scales of their head [6] and are mainly used to detect light.
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]
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 greatest predator of the ground squirrel is a snake—the type of snake varying by the locality. As a result, ground squirrels have evolved to perform anti-snake displays to defend themselves. [6] These squirrels tend to be put on a prominent display, specifically by moving their tail back-and-forth horizontally.
Like many insect body parts, including mandibles, antennae and stylets, cerci are thought to have evolved from what were legs on the primal insect form, [3] a creature that may have resembled a velvet worm, Symphylan or a centipede, worm-like with one pair of limbs for each segment behind the head or anterior tagma.
This small species rarely exceeds 32 in (81.3 cm) in length. It has a large, rounded head, and fairly heavy body for its size, with eyes with vertical pupils. Like other rattlesnakes, its tail has a rattle, which is composed of keratin. Each time the snake sheds its skin, a new segment is added to the rattle.