parasphenoid


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parasphenoid

[¦par·ə′sfē‚nȯid]
(vertebrate zoology)
A bone in the base of the skull of many vertebrates.
References in periodicals archive ?
The pterygoids join anterior to the posterior interpterygoid vacuities, covering the parasphenoid, as in most of the brachauchenine pliosaurids (Williston, 1903; Schumacher et al., 2013; Benson and Druckenmiller, 2014; Paramo-Fonseca et al., 2016).
From the region of the parasphenoid bone (the parasphenoidale) we highlight the projection of the rostro-parasphenoidal (Rostrum parasphenoidale--RP, Figures.
The palate exhibits two interpterygoid vacuities: the anterior interpterygoid vacuity is lanceolate with a pointed anterior and a more rounded posterior margin; the posterior interpterygoid vacuity is more rounded with a slightly pointed anterior end, and is divided longitudinally by the parasphenoid, as is usual in plesiosaurs (Andrews, 1910, 1913).
The parasphenoid is a triradial bone observed in the anterior region of the pituitary fenestra.
The third synapomorphy concerns the presence of a 'tongue-bite mechanism' with dorsal teeth on parasphenoid, a feature that is homoplasy free within the fishes examined (261: 0 [right arrow] 1).
[7] Anterolateral process of parasphenoid (Costa 1998a) (CI: 0.16; RI: 0.78): (0) short, free; (1) long, attached to pterosphenoid.
owstoni: "Cranium thin and papery; interorbital space and occiput flat, the former about 3.3 times in base of the cranium; preocular, postocular, tympanic and parietal spines present, but small and weak; nuchal spines sometimes present; supraocular and coronal spines absent; cranial ridges absent except for the parietal ridges which are low but never scaled over; parietals separated; mesethmoid processes never directed upward; base of cranium markedly curved; ventral process of basisphenoid feeble, never attached to the parasphenoid; nasal spines low, but strong; preorbital lobes without spines; second suborbital bone much wider than long.
The toothplates consist of two elements; the basibranchial and parasphenoid. The plates described herein are similar to those tentatively referred to Casierius heckelii by Huggins (1990) from the Trinity Group.
Vertical, complete laminar bony connection mesially to the eye between frontal, dorsally, and parasphenoid, ventrally.
Anatomical abbreviations are:a-a, angular-articular; bo, basioccipital; de, dentary; fr, frontal; fv, facet on maxilla for articulation with vomer; ipr, internal (anterior) process of the maxilla; le, lateral ethmoid; mpr, maxillary (posterior) process of the maxilla; rex, maxilla(e); ha, nasal; nc, nutrient canal; pa, parasphenoid; pd, predentary; pmx, premaxilla(e); pn, prenasal; pop, preopercle; pt, pterygoid; qu, quadrate; sph, sphenotic; tr, triangular region of maxilla; vo, vomer.