Stygivenator molnari (Paul, 1988) Olshevsky, G., 1995

Olshevsky, G., 1995, The origin and evolution of the Tyrannosaurids, Part 1, Dino-Frontline 9, pp. 92-119 : 2

Box 2: Description of Stygivenator

Linnaean hierarchy:

Paraclass Reptilia

Parasubclass Diapsida

Paramfraelass Archosauria

Parasuperorder Theropodomorpha

Paraorder Theropoda

Suborder Tyrannosauria nov.

Family Tyrannosauridae

Subfamily Shanshanosaurinae nov.

Genus Stygivenator nov.

Type species Stygivenator molnari (Paul, 1988) n. comb.

Synonyms:

“Jordan theropod” of Molnar, 1978

Aublysodon molnaris Paul, 1988 [sic]

Aublysodon molnari Paul, 1989

Etymology: Stygi-, Latinized combining form of Styx, one of the three rivers of Hades, the underworld of Greek mythology, referring to the Hell Creek Formation, in which the type specimen was discovered; and -venator, combining form of venator, Latin for “hunter”; thus, “Hell Creek hunter"

Holotype specimen of type species: LACM 28471 (figure above by Tracy Lee Ford, view of left side of reconstructed skull; scale bar = 10 cm), associated skull material including the anterior portions of nasals and maxillae with teeth, a premaxillary tooth, incomplete left and right frontals and parietals, fragment of surangular including the jaw joint, and anterior portions of both dentaries with teeth. Presently at the Los Angeles County Museum of Natural History. The individual may have been subadult or even juvenile. An endocranial mold has been prepared from the specimen.

Type locality and horizon: Dark gray clay of the Hell Creek Formation on the Lester D. Engdahl ranch (not, as originally noted, the F. S. McKeever ranch) near Jordan, Garfield County, Montana, USA, near a large ceratopid skull (probably Triceratops ). Discovered in the summer of 1966 by Harley Garbani, on a Los Angeles County Museum expedition to Jordan under the direction of J. Reed MacDonald.

Diagnosis: Stygivenator is a shanshanosaurine genus characterized by several very long anterior maxillary and dentaxy teeth. The height of the largest anterior maxillary tooth equals or even surpasses the depth of the dentary at its location, so that were the jaws to close completely, the tips of the anterior maxillary teeth would extend slightly below the ventral margin of the snout. Anterior premaxillary tooth is considerably narrower in lateral view than the lectotype tooth of Aublysodon mirandus (see figure below) and somewhat smaller, precluding reference to that doubtful species.

The tooth row of the anterior portion of the dentary, including the first three dentary teeth, is elevated above the level of the remainder of the tooth row, and the anterior dentary teeth are procumbent.

Referred specimens: None

Figures

Holotype specimen of type species: LACM 28471 (figure above by Tracy Lee Ford, view of left side of reconstructed skull; scale bar = 10 cm), associated skull material including the anterior portions of nasals and maxillae with teeth, a premaxillary tooth, incomplete left and right frontals and parietals, fragment of surangular including the jaw joint, and anterior portions of both dentaries with teeth. Presently at the Los Angeles County Museum of Natural History. The individual may have been subadult or even juvenile. An endocranial mold has been prepared from the specimen.