Describer

Brusatte, Benson, Chure, Xu, Sullivan, Hone (2009) vs Hu, 1964

Time

Cretaceous Early Barremian Aptian

Classification

Saurischia Theropoda Tetanurae [Allosauroidea] Carcharodontosauridae

Diet

Carnivore

Fossilsite

Lower Ulansuhai Formation of Dashuigou Group, Nei Mongol Zizhiqu, China

Info

Genus - Typespecies - Skull

Shaochilong maortuensis (Brusatte, Benson, Chure, Xu, Sullivan, Hone 2009) > Chilantaisaurus maortuensis (Hu, 1964)

Abstract

(Brusatte et al 2009) Little is known about the evolution of largebodied theropod dinosaurs during the Early to mid Cretaceous in Asia. Prior to this time, Asia was home to an endemic fauna of basal tetanurans, whereas terminal Cretaceous ecosystems were dominated by tyrannosaurids, but the intervening 60 million years left a sparse fossil record. Here, we redescribe the enigmatic large-bodied Chilantaisaurus maortuensis from the Turonian of Inner Mongolia, China. We refer this species to a new genus, Shaochilong, and analyze its systematic affinities. Although Shaochilong has previously been allied with several disparate theropod groups (Megalosauridae, Allosauridae, Tyrannosauroidea, Maniraptora), we find strong support for a derived carcharodontosaurid placement. As such, Shaochilong is the first unequivocal Asian member of Carcharodontosauridae, which was once thought to be restricted to Gondwana. The discovery of an Asian carcharodontosaurid indicates that this clade was cosmopolitan in the Early to mid Cretaceous and that Asian largebodied theropod faunas were no longer endemic at this time. It may also suggest that the ascent of tyrannosaurids into the large-bodied dinosaurian predator niche was a late event that occurred towards the end of the Cretaceous, between the Turonian and the Campanian.

Etymology

Shaochi Chinese for “shark tooth,” referring to the “sharktoothed” carcharodontosaurid theropods; long Chinese for dragon.

Partial skull and postcranial skeleton.

IVPP (Institute of Vertebrate Paleontology and Paleoanthropology) V2885.1-7, braincase, frontals, parietals, right nasal, right maxilla, quadrates, axis, and six caudal vertebrae, found associated (Hu 1964). All elements seem to represent a single individual, based on size, matching
articulations, and/or shared phylogenetic affinity.

Locality and horizon

Ulansuhai Formation, Maortu, People’s Republic of China (60 km north of Chilantai, Inner Mongolian Autonomous Region). The Ulansuhai Formation is often regarded as Aptian-Albian (late Early Cretaceous) based on perceived faunal similarities to other deposits of this age (e.g., Weishampel et al. 2004). However, radiometric dating of underlying strata indicates a maximum age of approximately 92 Ma (Turonian, early Late Cretaceous [“mid Cretaceous”]; Kobayashi and Lu 2003; Benson and Xu 2008).

Diagnosis

Allosauroid theropod possessing the following autapomorphies: maxillary antorbital fossa reduced in extent and nearly absent; paradental groove on medial surface of maxilla absent; deep, dorsoventrally oriented grooves located dorsally on maxillary interdental plates; pneumatic recess penetrates to posterior end of nasal; sagittal crest on frontal; large pneumatic foramen at anterodorsal corner of dorsal tympanic recess of prootic.

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