combining form repr. Gr. τρίγωνο-ς adj. three-cornered, triangular, neut. τρίγωνον as sb. a triangle; used in several scientific terms. Trigonocephale, -cephalous adjs., Zool. [Gr. κεφαλή head], having a triangular head, as a serpent of the genus Trigonocephalus; So Trigonocephalic a. Anthrop., having a malformation of the skull, caused by premature closing of the medio-frontal suture, in which the sides are flat and converge to an apex in front; Trigonocephaly, the condition of being trigonocephalic. Trigonocerous a., Zool. [Gr. κέρας horn], having horns of triangular section. Trigonocuneate a. [L. cune-us wedge], triangularly wedge-shaped. Trigonodont a., Comp. Anat. [Gr. ὀδούς, ὀδοντ- tooth], having the primitive cusps of the molar teeth arranged in a triangle. Trigonotype, Geom. [Gr. τύπος figure, image, TYPE], name for a trigonal trapezohedron (Cent. Dict., 1891).
1865. Morn. Star, 13 March. A *trigonocephale black serpent, brought over in 1842, is alive.
1878. Bartley, trans. Topinard’s Anthrop., v. 176. *Trigonocephalic, skull triangular at the top anteriorly, supposed to be owing to the medio-frontal synostosis. Ibid., Index, *Trigonocephaly.
1904. Duckworth, Morphol. & Anthropol., x. 253. A skull which viewed from above presents a peaked or rostrated appearance and has been described as triangular or trigonocephalic.
1848. Smart, *Trigonocerous, having three-angled horns,—applied to a species of fossil stag.
1864. in Webster.
1822. J. Parkinson, Outl. Oryctol., 224. *Trigono-cuneate, rather smooth on the upper part, longitudinally sulcated.
1897. H. F. Osborn in Amer. Nat., Dec., 1002. *‘Trigonodont’ is most appropriate because the first step in molar morphology is to identify the primitive triangle.
