Komodo Reptile Scales

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At the end of the ventral scales of the snake is a cloacal plate that protects the opening to the cloaca (a shared opening for waste and reproductive material to pass) on the underside near the tail. This scale has also been the anal scale, which is a misnomer since it does not cover an anus but a cloaca. This cloacal scale may be single or paired. Most authors have differentiated between single and divided cloacal scales. However, based on the origin of scales during development, a scale does not spontaneously divide, but it originates as paired structures that subsequently overlap. The part of the body beyond the cloacal scale is considered to be the tail. [13] Brysse, K. (2008). "From weird wonders to stem lineages: The second reclassification of the Burgess Shale fauna". Studies in History and Philosophy of Science Part C: Biological and Biomedical Sciences. 39 (3): 298–313. doi: 10.1016/j.shpsc.2008.06.004. PMID 18761282. Most reptiles are diurnal animals. The vision is typically adapted to daylight conditions, with color vision and more advanced visual depth perception than in amphibians and most mammals. a b Landberg, Tobias; Mailhot, Jeffrey; Brainerd, Elizabeth (2003). "Lung ventilation during treadmill locomotion in a terrestrial turtle, Terrapene carolina". Journal of Experimental Biology. 206 (19): 3391–3404. doi: 10.1242/jeb.00553. PMID 12939371. a b Piñeiro, Graciela; Ferigolo, Jorge; Ramos, Alejandro; Laurin, Michel (2012). "Cranial morphology of the Early Permian mesosaurid Mesosaurus tenuidens and the evolution of the lower temporal fenestration reassessed". Comptes Rendus Palevol. 11 (5): 379–391. Bibcode: 2012CRPal..11..379P. doi: 10.1016/j.crpv.2012.02.001.

There is evidence that reptiles are sentient and able to feel emotions including anxiety and pleasure. [130] Defense mechanisms [ edit ] Spotila, J.R.; O'Connor, M.P.; Dodson, P.; Paladino, F.V. (1991). "Hot and cold running dinosaurs: body size, metabolism and migration". Modern Geology. 16: 203–227.

Identification of cephalic scales is most conveniently begun with reference to the nostril, which is easily identified on a snake. There are two scales enclosing the nostril which are called the nasals. In colubrids, the nostril lies between the nasals, while in vipers it lies in the centre of a single nasal scale. [22] The outer nasal (near the snout) is called the prenasal while the inner nasal (near the eye) is called the postnasal. Along the top of the snout connecting the nasals on both sides of the head are scales called internasals. Between the two prenasals is a scale at the tip of the snout called the rostral scale. [22] Hearing in humans relies on 3parts of the ear; the outer ear that directs sound waves into the ear canal, the middle ear that transmits incoming sound waves to the inner ear, and the inner ear that helps in hearing and keeping your balance. Unlike humans and other mammals, snakes do not possess an outer ear, a middle ear, and a tympanum but have an inner ear structure with cochleas directly connected to their jawbone. [93] They are able to feel the vibrations generated from the sound waves in their jaw as they move on the ground. This is done by the use of mechanoreceptors, sensory nerves that run along the body of snakes directing the vibrations along the spinal nerves to the brain. Snakes have a sensitive auditory perception and can tell which direction sound being made is coming from so that they can sense the presence of prey or predator but it is still unclear how sensitive snakes are to sound waves traveling through the air. [94] Skin [ edit ] Skin of a sand lizard, showing squamate reptiles iconic scales Some squamate species (e.g., pythons and monitor lizards) have three-chambered hearts that become functionally four-chambered hearts during contraction. This is made possible by a muscular ridge that subdivides the ventricle during ventricular diastole and completely divides it during ventricular systole. Because of this ridge, some of these squamates are capable of producing ventricular pressure differentials that are equivalent to those seen in mammalian and avian hearts. [70] a b Laurin, M.; Reisz, R.R. (1995). "A reevaluation of early amniote phylogeny" (PDF). Zoological Journal of the Linnean Society. 113 (2): 165–223. doi: 10.1111/j.1096-3642.1995.tb00932.x. Scale arrangements are important, not only for taxonomic utility, but also for forensic reasons and conservation of snake species. [19]

Cisneros, Juan C.; Damiani, Ross; Schultz, Cesar; daRosa, Átila; Schwanke, Cibele; Neto, Leopoldo W.; Aurélio, Pedro L.P. (2004). "A procolophonoid reptile with temporal fenestration from the middle Triassic of Brazil". Proceedings of the Royal Society B. 271 (1547): 1541–1546. doi: 10.1098/rspb.2004.2748. PMC 1691751. PMID 15306328. Despite the early proposals for replacing the paraphyletic Reptilia with a monophyletic Sauropsida, which includes birds, that term was never adopted widely or, when it was, was not applied consistently. [2] Bearded dragon ( pogona) skeleton on display at the Museum of Osteology Antediluvian monster", a Mosasaurus discovered in a Maastricht limestone quarry, 1770 (contemporary engraving) Exposed parts of reptiles are protected by scales or scutes, sometimes with a bony base ( osteoderms), forming armor. In lepidosaurians, such as lizards and snakes, the whole skin is covered in overlapping epidermal scales. Such scales were once thought to be typical of the class Reptilia as a whole, but are now known to occur only in lepidosaurians. [ citation needed] The scales found in turtles and crocodiles are of dermal, rather than epidermal, origin and are properly termed scutes. [ citation needed] In turtles, the body is hidden inside a hard shell composed of fused scutes. 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] Lizard scales [ edit ] Lizard head scales, from Boulenger 1890: 168. [3]

Snakes of Northwest Arizona

In the 18th century, the reptiles were, from the outset of classification, grouped with the amphibians. Linnaeus, working from species-poor Sweden, where the common adder and grass snake are often found hunting in water, included all reptiles and amphibians in class "III – Amphibia" in his Systema Naturæ. [7]