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The apparent absence of these glands in non-mammaliaformes may suggest that fur did not originate until that point in synapsid evolution. [40] It is possible that fur and associated features of true warm-bloodedness did not appear until some synapsids became extremely small and nocturnal, necessitating a higher metabolism. [40]
While reptile scales use a sophisticated naming system (see figures), there has been a certain confusion because of synonymous names. For instance, the ventral scales are often called ventrals but gastrosteges is common in the older literature. In more recent publications they are often abbreviated as VSR (for ventral scale rows) or simply V. [4]
Unlike amphibians, reptiles do not have an aquatic larval stage. Most reptiles are oviparous, although several species of squamates are viviparous, as were some extinct aquatic clades [6] – the fetus develops within the mother, using a (non-mammalian) placenta rather than contained in an eggshell. As amniotes, reptile eggs are surrounded by ...
The scales of all reptiles have an epidermal component (what one sees on the surface), but many reptiles, such as crocodilians and turtles, have osteoderms underlying the epidermal scale. Such scales are more properly termed scutes. Snakes, tuataras and many lizards lack osteoderms. All reptilian scales have a dermal papilla underlying the ...
A dragonfly in its radical final moult, metamorphosing from an aquatic nymph to a winged adult.. In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is a process by which an animal casts off parts of its body to serve some beneficial purpose, either at specific times of the year, or at specific points in ...
Reptiles evolved from amphibious ancestors which left the water and became terrestrial. To prevent loss of moisture, reptilian skin lost the softness and moisture of amphibian skin and developed a thick stratum corneum with multiple layers of lipids, which served as an impermeable barrier, as well as providing protection from ultraviolet light. [5]
Snake scales are not discrete, but extensions of the epidermis—hence they are not shed separately but as a complete outer layer during each molt, akin to a sock being turned inside out. [61] Snakes have a wide diversity of skin coloration patterns which are often related to behavior, such as the tendency to have to flee from predators.
A = Anapsid, B = Synapsid, C = Diapsid. It was traditionally assumed that first reptiles were anapsids, having a solid skull with holes only for the nose, eyes, spinal cord, etc.; [10] the discoveries of synapsid-like openings in the skull roof of the skulls of several members of Parareptilia, including lanthanosuchoids, millerettids, bolosaurids, some nycteroleterids, some procolophonoids and ...