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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 ...
The scales may be ossified or tubercular, as in the case of lizards, or modified elaborately, as in the case of snakes. [1] The scales on the top of lizard and snake heads has also been called pileus, after the Latin word for cap, referring to the fact that these scales sit on the skull like a cap. [2]
The scales and scutes of birds were thought to be homologous to those of reptiles, [4] but are now agreed to have evolved independently, being degenerate feathers. [ 5 ] [ 6 ] Carcharodontosaurid theropod dinosaur Concavenator , is known to have possessed these feather-derived tarsal scutes.
Lizard is the common name used for all squamate reptiles other than snakes (and to a lesser extent amphisbaenians), encompassing over 7,000 species, [1] ranging across all continents except Antarctica, as well as most oceanic island chains.
These differed in structure from the scales of lizards and snakes, which are an epidermal feature (like mammalian hair or avian feathers). [34] Recently, skin impressions from the genus Ascendonanus suggest that at least varanopsids developed scales similar to those of squamates. [35]
The feather fossils obtained from this specimen also suggest the presence of Stage IIIa feathers, a new discovery that indicates more complex feather structures were present in pterosaurs. The study describing this specimen further clarifies the timeline of avian feather evolution and suggests that the feather-specific melanosome signaling ...
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.
The hair cells are unspecialised, innervated by both afferent and efferent nerve fibres, and respond only to low frequencies. Though the hearing organs are poorly developed and primitive with no visible external ears, they can still show a frequency response from 100 to 800 Hz , with peak sensitivity of 40 dB at 200 Hz.