[D] Siluosaurus zhangqiani [sG] [T]
Describer
Dong, 1997
Time
Cretaceous Early ?Barremian
Classification
Ornithischia Ornithopoda
Diet
Herbivore
Fossilsite
Gongpoquan Basin, Xinminbao Group, Mazongshan Area, Gansu Province, China
Info
Genus - Typespecies
Etymology
The generic name is derived from Chinese Pinyin \\\"Silu\\\" (meaning Silk Road), along which the Dinosaur Expedition was carried out in 1992. The \\\"sours\\\" is from Greek for a lizard. The specific name is in honor of Zhang Qian (who was a diplomatist of the Han dynasty B.C. 206 ~A.D. 23), for his contributuons to establishing the diplomatic and trade relationships between China and countries along the \\\"Silk Road\\\" during his time.
Material
A complete premaxillary tooth and a nearly complete cheek tooth collected from Xinminbao Group. IVPP V. 11117, 1-2, field number 9208-21-4.
Diagnosis
The smallest known hypsilophodontid taxon, differing from other members of the family in the followings: premaxillary teeth possesing a spear-shaped, symmetrical (both-sides) crown (width-hight 1/1), a relatively long root with no cingulum; crowns of premaxillary teeth lacking recurved tip but bearing fine ridges; crowns of cheek teeth asymmetrical, with cingulum separated from root; lingual surface of cheek teeth appearently flat, with five fine ridges (denticles) that are straight and reach the base of the crown but lacking a midridge (center denticle); labial surface of cheek teeth slightly convex, with inclined longitudinal ridges that do not reach the base of the crown and a pronounced central ridge that is triangular in outline.
Description
V 11123 is a premaxillary tooth. It is 7 mm high and 2.2 mm wide across the base of the crown. The crown is nearly symmetrical on both the libgual and labial surfaces, in contrast to the condition seen in Hypsilophodon (Galton, 1974) in which the labial surface is less comvex than the lingual surface. The root is long and clearly separated from the crown by a slight constriction. The root is circular in the cross-section. The crown is slightly yellow in colour but the root is brown. Both surfaces are smooth and obviously covered by a layer of thin enamal. These features are simialrly present in the premaxillary teeth of Galtonia from the Upper Triassic of Pennsylvania.
The cheeck tooth is represented by a nearly complete crown. The crown is 3.7 mm in height and 4.2 mm in width. As in other hypsilophodontids, the crown bears a fine ridge. The crown is asymmetrical on both the labial and lingual surfaces and distincly separated by a cingulum from the root. The lingual surface seems to be flat. with five fine ridges (denticles) that are straight and reach the base of the crown. There is no midrange (center denticle). The labial surface is slightly convex and covered by inclined longitudinal ridges that do not reach the base of the crown. As is the premaxillary tooth, a central ridge that is triangular in outline is present on the labial surface.
Dong, 1997
Time
Cretaceous Early ?Barremian
Classification
Ornithischia Ornithopoda
Diet
Herbivore
Fossilsite
Gongpoquan Basin, Xinminbao Group, Mazongshan Area, Gansu Province, China
Info
Genus - Typespecies
Etymology
The generic name is derived from Chinese Pinyin \\\"Silu\\\" (meaning Silk Road), along which the Dinosaur Expedition was carried out in 1992. The \\\"sours\\\" is from Greek for a lizard. The specific name is in honor of Zhang Qian (who was a diplomatist of the Han dynasty B.C. 206 ~A.D. 23), for his contributuons to establishing the diplomatic and trade relationships between China and countries along the \\\"Silk Road\\\" during his time.
Material
A complete premaxillary tooth and a nearly complete cheek tooth collected from Xinminbao Group. IVPP V. 11117, 1-2, field number 9208-21-4.
Diagnosis
The smallest known hypsilophodontid taxon, differing from other members of the family in the followings: premaxillary teeth possesing a spear-shaped, symmetrical (both-sides) crown (width-hight 1/1), a relatively long root with no cingulum; crowns of premaxillary teeth lacking recurved tip but bearing fine ridges; crowns of cheek teeth asymmetrical, with cingulum separated from root; lingual surface of cheek teeth appearently flat, with five fine ridges (denticles) that are straight and reach the base of the crown but lacking a midridge (center denticle); labial surface of cheek teeth slightly convex, with inclined longitudinal ridges that do not reach the base of the crown and a pronounced central ridge that is triangular in outline.
Description
V 11123 is a premaxillary tooth. It is 7 mm high and 2.2 mm wide across the base of the crown. The crown is nearly symmetrical on both the libgual and labial surfaces, in contrast to the condition seen in Hypsilophodon (Galton, 1974) in which the labial surface is less comvex than the lingual surface. The root is long and clearly separated from the crown by a slight constriction. The root is circular in the cross-section. The crown is slightly yellow in colour but the root is brown. Both surfaces are smooth and obviously covered by a layer of thin enamal. These features are simialrly present in the premaxillary teeth of Galtonia from the Upper Triassic of Pennsylvania.
The cheeck tooth is represented by a nearly complete crown. The crown is 3.7 mm in height and 4.2 mm in width. As in other hypsilophodontids, the crown bears a fine ridge. The crown is asymmetrical on both the labial and lingual surfaces and distincly separated by a cingulum from the root. The lingual surface seems to be flat. with five fine ridges (denticles) that are straight and reach the base of the crown. There is no midrange (center denticle). The labial surface is slightly convex and covered by inclined longitudinal ridges that do not reach the base of the crown. As is the premaxillary tooth, a central ridge that is triangular in outline is present on the labial surface.