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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 ...
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. The squamosal and quadratojugal bones together form the cheek region [4] and may provide muscular attachments for facial muscles. [5]
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Streptostyly is the fore-aft movement of the quadrate about the otic joint (quadratosquamosal joint), although transverse movements may also be possible. [2] Many hypothesized types of kinesis require basal joint kinesis ( neurokinesis of Iordansky, 1990), that is, movement between the braincase and palate at the basipterygoid joint.
Their quadrate bone articulation with the lower jaw resembled that of a pelican or other birds that can open their beak widely. Altogether, the pseudotooth birds would have filled an ecological niche almost identical to that of the larger fish-eating pteranodontian pterosaurs , whose extinction at the end of the Cretaceous may well have paved ...
The quadrate not only contacts the lower jaw, but also connects to the inner face of the quadratojugal and is overlapped by the 'hood' of the squamosal. The appearance of the quadrate is yet another unique aspect of Vancleavea. In most basal archosauriforms, the quadrate is tall and straight, but in Vancleavea it is short, stout, and arched ...
As a result, most of the posterior skull is clustered together, and the infratemporal fenestra is reduced to a small diagonal hole. The quadratojugal is a curved sliver of bone which twists back alongside the quadrate. Relative to T. longobardicus, the quadrate has a larger pterygoid ramus and a strongly hooked projection at its upper extent ...
The prefrontal is a smaller bone on the side margin of the skull roof between the frontal, lacrimal, and nasal. [25]: 38 predentary The predentary is an unpaired bone found in front of the dentaries of the lower jaw that formed the lower beak in ornithischians. [1]: 142 Its presence is considered an ornithischian synapomorphy. [99] premaxilla