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 parasphenoid is a triradial bone observed in the anterior region of the pituitary fenestra.
Within the Neomorphinae, there are five characteristics that are shared by the group Geococcyx, Morococcyx and Neomorphus that differ from Tapera and Dromococcyx: the lateral length of the frontal is larger, the lateral process of the parasphenoid is reduced, the lateral orbitonasal foramen is larger, the bony lamella covering the nasal aperture is larger and the dorsal process of the nasal is absent.
3 times in base of the cranium; cranial spines well developed, directed straightly backward; preocular, postocular, tympanic and parietal spines always present supraocular, corneal and nuchal spines absent; parietal ridges high and naked; frontal ridges low but distinct, the space between them shallowly concave; supraocular edges low or depressed, as high as or lower than the frontal ridges; mesethmoid processes slightly elevated upward; base of cranium some-what curved; parietals separated or partly meeting; ventral process of the basisphenoid well developed, entirely meeting the parasphenoid.
The cultriform process of the parasphenoid is pointed and extends to the level of the neopalatines in E.
Its counter element, the parasphenoid toothplate, has a concave occlusal surface (Fig.
However, this is not the case and in fact Laurin and Reitz (1995) used 'parasphenoid wings' to describe a condition where the wing is a raised, posterior extension of the parasphenoid that extends beyond its central depressed portion posteriorly.
Vertical, complete laminar bony connection mesially to the eye between frontal, dorsally, and parasphenoid, ventrally.
Two flat elements, presumably the ventral surface of the parasphenoid (pa) and a small portion of the vomer (vo), are visible.
A monogeneric atheriniform family with the parasphenoid concave rather than convex, parasphenoid myodomes present; mesethmoid morphology unique, nasal septum formed by ethmoid and mesethmoid; parietals not contributing to posttemporal fossa; anterior vertebral parapophyses with lateral ridges; interdorsals absent; cleithrum dorsal enclosure absent; membrane just posterior to genital opening; and pelvic posteromedial process elongate.
Material: A parasphenoid (or), a right mandible (ch), two sacra (ch and sd), a left and a right ilium (rd and sd), and a femur (ch) [MSUVP 2052] identified by JAH.
Both parasphenoid and basibranchial toothplates, referrable to the Paralbulinae, are known from the site.