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Lizards and snakes share a movable quadrate bone, distinguishing them from the rhynchocephalians, which have more rigid diapsid skulls. [5] Some lizards such as chameleons have prehensile tails, assisting them in climbing among vegetation. [6] As in other reptiles, the skin of lizards is covered in overlapping scales made of keratin. This ...
For instance, descendants of the first reptiles include modern reptiles, mammals and birds; the agnathans have given rise to the jawed vertebrates; the bony fishes have given rise to the land vertebrates; a group of amphibians, the labyrinthodonts, have given rise to the reptiles (traditionally including the mammal-like synapsids), which in ...
The number of vertebrae in a region can vary but overall the number remains the same. In a human spinal column, there are normally 33 vertebrae. [3] The upper 24 pre-sacral vertebrae are articulating and separated from each other by intervertebral discs, and the lower nine are fused in adults, five in the sacrum and four in the coccyx, or tailbone.
The hemipenis is the intromittent organ of Squamata, [4] which is the second largest order of vertebrates with over 9,000 species distributed around the world. They differ from the intromittent organs of most other amniotes such as mammals, archosaurs and turtles that have a single genital tubercle, as squamates have the paired genitalia remaining separate. [5]
Squamata (/ s k w æ ˈ m eɪ t ə /, Latin squamatus, 'scaly, having scales') is the largest order of reptiles, comprising lizards and snakes.With over 12,162 species, [3] it is also the second-largest order of extant (living) vertebrates, after the perciform fish.
Glass lizards have eyelids and can blink, but snakes have immovable, transparent scales and can’t blink. Snakes can unhinge their jaws to swallow large prey, but glass lizards can’t.
Reptiles, from Nouveau Larousse Illustré, 1897–1904, notice the inclusion of amphibians (below the crocodiles). In the 13th century, the category of reptile was recognized in Europe as consisting of a miscellany of egg-laying creatures, including "snakes, various fantastic monsters, lizards, assorted amphibians, and worms", as recorded by Beauvais in his Mirror of Nature. [7]
They are adapted to arid or semiarid areas. The spines on the lizard's back and sides are modified reptile scales, which prevent water loss through the skin, whereas the horns on the head are true horns (i.e., they have a bony core). A urinary bladder is absent. [1] Of the 21 species of horned lizards, 15 are native to the USA.