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The quadrate bone is a skull bone in most tetrapods, including amphibians, sauropsids (reptiles, birds), and early synapsids. In most tetrapods, the quadrate bone connects to the quadratojugal and squamosal bones in the skull, and forms upper part of the jaw joint. The lower jaw articulates at the articular bone, located at the rear end of the ...
The skull of Python reticulatus.. The skull of a snake is a very complex structure, with numerous joints to allow the snake to swallow prey far larger than its head.. The typical snake skull has a solidly ossified braincase, with the separate frontal bones and the united parietal bones extending downward to the basisphenoid, which is large and extends forward into a rostrum extending to the ...
Snakes and legless lizards have evolved the complete loss of their limbs. The upper jaw of Squamates is movable on the cranium, a configuration called kinesis. [28] This is made possible by a loose connection between the quadrate and its neighboring bones. [29] Without this, snakes would not be able consume prey that are much larger than ...
Modern examples of tetrapods without a quadratojugal include salamanders, mammals, birds, and squamates (lizards and snakes). [3] In tetrapods with a quadratojugal bone, it often forms a portion of the jaw joint. Developmentally, the quadratojugal bone is a dermal bone in the temporal series, forming the original braincase.
In snakes, the columella would be attached directly to the quadrate bone (c). Snakes have lost a tympanic membrane, and hence a distal attachment for the columella. The columella is instead connected to the quadrate bone of the jaw. Thus, snakes are able to detect and localize ground vibrations through the lower jaw, rather than the sides of ...
The skull of a snake differs from a lizards in several ways. Snakes have more flexible jaws, that is, instead of a juncture at the upper and lower jaw, the snake's jaws are connected by a bone hinge that is called the quadrate bone. Between the two halves of the lower jaw at the chin there is an elastic ligament that allows for a separation.
Relatively small snakes, leptotyphlopids rarely exceed 30 cm (12 in) in length; only Trilepida macrolepis and Leptotyphlops occidentalis grow larger. The cranium and upper jaws are immobile and no teeth are in the upper jaw. The lower jaw consists of a much elongated quadrate bone, a tiny compound bone, and a relatively larger dentary bone. [3]
Snakes possess the most exceptional cranial kinesis of any tetrapod. In amphibians, cranial kinesis varies, but has yet to be observed in frogs and is rare in salamanders . Almost all fish have highly kinetic skulls, and teleost fish have developed the most kinetic skulls of any living organism.