JURASSIC DINOSAUR FAUNAS IN ZIGONG - 自贡恐龙博物馆

that lateral margin of squamosal distinctly arched medially; exoccipital not contacting its
opposite on occipital condyle; a median ventral ridge of pterygoid originated from main body of
pterygoid; and anteriorly positioned choanae.
In addition, splenial entering symphysis anteriorly for a relatively long distance,
well-sculptured outer surface of dentary and ventral surface of splenial, extraordinarily expanded
scapular blade, presence of coracoid foramen, strongly thickened and expanded head of humerus,
well-developed deltopectoral crest, a developed process of radiale for ulna, six rows of ventral
osteoderms of presacral, and three rows of ventral osteoderms of caudal may be unique to H.
chowi , while these characters are uncertain in H. dashanpuensis.
Holotype A nearly complete skeleton including complete skull and lower jaws, most of
vertebrae, some bones of girdles and limbs, and most osteoderms. ZDM 0146.
Locality and horizon Zigong Dairy Factory, Huidong, Zigong; Shangshaximiao
Formation, Late Jurassic.
Order Saurischia
Suborder Theropoda
Infraorder Carnosauria
Family Megalosauridae Huxley, 1869
Genus Szechuanosaurus Young, 1942
Revised diagnosis Medium-sized megalosaur with body length of 4~7 m. It is
characterized by skull shorter than neck; large first antorbital fenestra, orbit and infratemporal
fenestra; very small second antorbital fenestra; penetrative maxillary fossa; low dentary;
distinctly compressed teeth with serrated anterior and posterior margins; dental formula Pm4 +
M15~17 / D15~16; 9~10 cervicals, 13 dorsals, 5 co-ossified sacrals; sacral neural spines not
fused; posterior caudals with elongated prezygapophyses; low ilium; distal end of pubis with an
undeveloped foot-like process; distal end of ischium expanded but lacking foot-like process; and
metatarsals not fused.
Type species Szechuanosaurus campi Young, 1942.
Szechuanosaurus campi Young, 1942
Revised diagnosis Medium-sized theropod about 5 m of body length. It is recognized by
distinctly compressed teeth with serrated anterior and posterior margins; thicker premaxillary
teeth trending to incisors, with symmetrical and medially bent crowns; 9 cervicals, 13 dorsals, 5
coalesced sacrals, and about 45 caudals; plate-like dorsal neural spines with a robust expanded
dorsal tip; sacral neural spines not fused; narrow neural spines of anterior caudals; posterior
caudals with elongate prezygapophyses; low ilium with its anterior process shorter than posterior
process; distal ends of pubis with an undeveloped foot-like process; forelimb about 2/5 of length
of hindlimb; femur longer than tibia; metatarsal II, III and IV not fused; metatarsal I and V
reduced; and compressed claws.
Holotype Several isolated teeth. IVPP V 235, V 236, V 238 and V 239.