Wu, Currie, Dong, Pan & Wang 2009
Saurischia Theropoda Tetanurae
Upper Lufeng Formation, Yunnan, China
A new theropod dinosaur, Shidaisaurus jiae gen, et sp. nov., has been desccribed on the basis of an incomplete skeleton. The specimen was found near the base of the Upper Lufeng Formation (early Middle Jurassic) in Yunnan, China. It is the first theropod dinosaur from the Middle Jurassic of Yunnan. Shidaisaurus jiae is distinguishable from the Jurassic theropods by certain features from the braincase, axis, and pelvic girdle. The absence of any pleurocoels in the axis or in any anterior dorsal vertebrae suggests that the new Lufeng theropod is relatively primitive and more plesiomorphic than most of the Middle to Late Jurassic theropods from China. Most Chinese taxa of Jurassic theropod dinosaurs have not been wel desdribed; a further detailed study will be necassary for us to determine their phylogenetic relationships with Shidaisaurus jiae.
Horizon and Locality: Near the base of the Upper Lufeng Formation (early Middle Jurassic): A'na, Laochangjing village, Chuanjie township, lufeng Countt, Yunnan, China
Holotype: Lufeng Dinosaur Museum-Lufeng Chuanjie A'na (LDM-LCA) 9701-IV, a partial skeleton that lacks most caudal vertebrae, ribs, pectoral girdles,a nd limb bones.
Etymology: Shidaisaurus is derived from the second word of Jin-Shidai, the name of the company who owns the "Jurassic World" at the fossil locality. The Chinese word "Shidai" represents times, age, era, and epoch. The specific name is derived from the first word of character of the Jin-Shidai Company. The Chinese word "Jin" is the metal gold and often used as the first word of names of companies of many kinds, indicating that the companies would stand up forever as gold would.
Diagnosis: A medium to large-sized theropod that differs from other tetanurans with the following combination of characters: supraoccipital excluded from the foramen magnum by exoccipitals; paroccipital process down turned slightly (approximately 110 degrees from vertical); axis with a large, sharply pointed epipophysis and a thin lamina between the epipophysis and neural spine that is broader than in other theropods where it is present; anteroventral to dorsoposterior pubic length is almost the same as the height of the iliac blade; lacks a ventral notch distal to the oburator process on the ischium; and has an ischium that is relatively long (more than 96% the length of the pubis.