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We dread from them as they may have the potential to wipe out us by their venom. They may be snakes. Snakes belong to the suborder Serpents and are legless, crawling and elongating reptiles. They will vary from lizards as they lack eyelid and external ears. They are really ectothermic, amniotes covered by overlapping scales like all other squamates. The skull bone fragments of snakes are demarcated by presence of a sizable number of bones that enable these to prey on a prey which is a lot bigger than them. Jaws are highly movable. They have an individual functional lung. Some kinds bear a pair of vestigial claws on either side of the cloaca. They can be found in every continents except Antarctica. Fifteen families have been identified comprising of 456 genera and 2,900 varieties. They range in proportions from 10 cm like that of thread snake to the bigger pythons and anacondas which are about 7.6 meters long. The recently discovered fossil of snake Titanoboa was about 15 meters long.
Snakes are thought to have evolved from their terrestrial or aquatic lizard ancestors during the Cretaceous period. Modern snakes appeared during the Paleocene period. Majority of the species are non-poisonous and the venomous species use their venom as a measure of self-defence. Some venomous snakes have the potential to kill even humans. Non-venomous snakes either swallow the prey alive or kill it by constriction. The modern English word snake comes from the Old English word snaca which means to crawl or to creep. Fossil record of snakes is relatively poor as the skeletons are relatively small making fossilization impossible. 150 million year old specimens of snakes have been discovered in South America and South Africa. Fossil records suggest that the snakes have evolved from the burrowing lizards. Primitive snakes among the modern ones are the pythons and the boas.
Snake skeleton is chiefly composed of skull, hyoid, vertebral column, vestiges and ribs of pelvis and hind limbs in the henophidian snakes. Skull includes a good braincase to which other bones are loosely articulated making the jaws flexible so that effective feeding and prey capture can commence. The kept and right sides of the low jaw are signed up with to a ligament while the posterior end of lower jaw is articulated with the quadrate making the jaw more mobile. Mandibles and quadrate help in picking sound borne vibrations also. Hyoid is a tiny bone located in the neck region serving for the attachment of the tongue muscles. Vertebral column comprises 200-400 vertebrae. Tail vertebrae fewer and lack ribs. Vertebrae of body bear two ribs. Vertebrae have strong articulation with muscles to be able to bring about effective locomotion in absence of limbs. Autotomy is absent in snakes. Pythons and boas have a set of vestiges of hind limbs by means of pelvic spurs present on either side of the cloaca consisting of the vestiges of ilium and femur.
Snakes are thought to have evolved from their terrestrial or aquatic lizard ancestors during the Cretaceous period. Modern snakes appeared during the Paleocene period. Majority of the species are non-poisonous and the venomous species use their venom as a measure of self-defence. Some venomous snakes have the potential to kill even humans. Non-venomous snakes either swallow the prey alive or kill it by constriction. The modern English word snake comes from the Old English word snaca which means to crawl or to creep. Fossil record of snakes is relatively poor as the skeletons are relatively small making fossilization impossible. 150 million year old specimens of snakes have been discovered in South America and South Africa. Fossil records suggest that the snakes have evolved from the burrowing lizards. Primitive snakes among the modern ones are the pythons and the boas.
Snake skeleton is chiefly composed of skull, hyoid, vertebral column, vestiges and ribs of pelvis and hind limbs in the henophidian snakes. Skull includes a good braincase to which other bones are loosely articulated making the jaws flexible so that effective feeding and prey capture can commence. The kept and right sides of the low jaw are signed up with to a ligament while the posterior end of lower jaw is articulated with the quadrate making the jaw more mobile. Mandibles and quadrate help in picking sound borne vibrations also. Hyoid is a tiny bone located in the neck region serving for the attachment of the tongue muscles. Vertebral column comprises 200-400 vertebrae. Tail vertebrae fewer and lack ribs. Vertebrae of body bear two ribs. Vertebrae have strong articulation with muscles to be able to bring about effective locomotion in absence of limbs. Autotomy is absent in snakes. Pythons and boas have a set of vestiges of hind limbs by means of pelvic spurs present on either side of the cloaca consisting of the vestiges of ilium and femur.
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