parasphenoid


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parasphenoid

(ˌpærəˈsfiːnɔɪd)
n
(Anatomy) a bone next to the sphenoid bone in the skull of some animals
adj
(Anatomy) of or relating to the parasphenoid bone
References in periodicals archive ?
1994) figured a dipnoan parasphenoid bone from the uppermost Famennian Witpoort Formation of South Africa, which is similar morphologically to that described as Andreyevichthys epitomus Krupina, 1987.
The parasphenoid and occipital bones are well mineralized but are not extremely dense.
In the parasphenoid bone region (Os parasphenoidale), the parasphenoid rostrum (Rostrum parasphenoidale--RP) (Fig.
Moreover, the parasphenoid is beginning to be observed in the region of the pituitary fenestra.
The neurocranium is not depressed; the vomeral tooth row is restricted to a small crest and the parasphenoid is straight in sagittal profile and thin.
In order to access the otoliths, the gill arches and flesh covering the parasphenoid bones were first removed.
3); one pair of slender uroneurals; three epurals; a free parhypural; three thin supraneurals, generally straight; two supernumerary spines on first dorsal pterygiophore; no procumbent spines (spurs); thin Y-shaped basisphenoid, free from parasphenoid and prootics; neurocranium with frontal tabs similar to Vincentia Castelnau, 1872 (Fraser 1972: pl 31); supramaxilla absent; posttemporal smooth or with 1-3 small serrae on posterior margin; preopercle with 2-3 small, widely spaced serrae near angle, ridge smooth; infraorbitals smooth; infraorbital shelf present on third bone; ring of scleral cartilage, no ossification present; 7 branchiostegals; ceratohyal notched, suture smooth with epihyal; urohyal with short anterior process.
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).
pachycephalus: "Cranium very thick and heavy; interorbital space deeply concave, about 3 1/2 in base of cranium; cranial spines broad and stout, the pointed tips directed backward; preocular, postocular, tympanic and parietal spines present; supraocular, coronal and nuchal spines absent; supraocular ridges exceedingly high and stout, forming a narrow flat area between them; frontal ridges barely evident, can not be seen without elimination of the skin; parietal ridges broad and high, but a little lower than the supraocular ridges; nasal spines stout, directed upward and slightly backward; mesethmoid processes strongly compressed, directed forward and upward; parietal bones separated; base of cranium straight; ventral process of basisphenoid entirely meeting the parasphenoid.
The cultriform process of the parasphenoid is blunt anteriorly, does not reach to the vomers, and does not taper.