[D] Beishanlong grandis [sG] [T]
Makovicky, Li, Gao, Lewin, Erickson & Norell, 2009
Cretaceous Early Aptian Albian
Saurischia Theropoda Tetanurae Coelurosauria Ornithomimosauria
Xinminpu Group, Yujingzi Basin, Gansu, China
The Ornithomimosaur (ostrich-mimic dinosaur), Beishanlong grandis, is described from from an associated, partial postcranial skeleton from the Aptian-Albian Xinminpu Group of northern Gansu, China. Beishanlong is similar to another Aptian-Albian ornithomimosaur, Harpymimus, with which it shares a phylogenetic position as more derived than the Barremian Shenzhousaurus and as sister to a Late Cretaceous clade composed of Garudimimus and the Ornithomimidae. Beishanlong is one of the largest definitive ornithomimosaurs yet described, though histological analysis shows that the holotype individual was still growing at its death. Together with the co-eval and sympatric therizinosaur Suzhousaurus and the oviraptorosaur Gigantoraptor, Beishanlong provides evidence for the parallel evolution of gigantism in separate lineages of beaked and possibly herbivorous coelurosaurs within a short time span in Central Asia.
Beishanlong from the Mandarin Bei Shan for Northern Mountain, and long for dragon; and grandis from the Latin in reference to the large size of this taxon.
FRDC-GS GJ (06) 01–18, associated postcranial skeleton; FRDC-GS GJ (unnumbered), hindlimb elements of large specimen; FRDC-GS JB(07)01-01, a pair of isolated pubes probably referable to this taxon. All material is housed at the Fossil Research and Development Center (FRDC), Third Geology and Mineral Resources Exploration Academy, Gansu Provincial Bureau of Geo-Exploration and Mineral Development in Lanzhou, China. Other institutional abbreviations are AMNH, American Museum of Natural History, New York, USA; IGM, Mongolian Institute of Geology, Ulanbaatar, Mongolia; RTMP, Royal Tyrrell Museum of Palaeontology, Drumheller, Canada.
Locality and horizon
White Ghost Castle field area, Yujingzi Basin, Gansu, China. The holotype derives from grey mudstones near the bottom of the Early Cretaceous (Aptian-Albian) Xinminpu Group exposed in the basin with a hadrosauroid (cf. Equijubus) dominated fauna. A second partial skeleton was collected from the overlying red beds, where small neoceratopsians (cf. Auroraceratops) are the dominant faunal element. Tang et al. (2001) and Li et al. (in press) provide further information on faunal associations of this taxon. An isolated pair of pubes probably referable to Beishanlong was found near the holotype at approximately the same level.
Large ornithomimosaur with notched anterior caudal neural spine; keeled midcaudal centra with divided neural spines and prominent ridges connecting pre- and postzygapophyses; scapula with pronounced fossa at rostral end of supraglenoid buttress; shallow coracoid with prominent lateral ridge emanating from coracoid tuber and deep notch between glenoid and postglenoid process; curved pollex ungual, but straighter unguals on digits II and III; curved ischial shaft; third metatarsal proximally pinched but visible along extensor surface of foot; curved pedal unguals. These traits represent a combination of unique, primitive and derived traits.