Describer

Sereno, Tan, Brusatte, Kriegstein, Zhao, and Cloward 2009

Time

Cretaceous Early Barremian Aptian

Classification

Saurischia Theropoda Tyrannosauria Tyrannosauridae

Diet

Carnivore

Fossilsite

Yixian Formation, Lujiatun Beds, Liaoning, China

Info

Holotype

LH PV18, partially articulated skeleton composed of disarticulated cranial bones representing most of the skull and postcranial skeleton, lacking portions of the forelimb and the distal one-half of the tail (beyond the eleventh caudal).

The holotype represents a young adult, as shown by fusion of the nasals and braincase elements in the skull and at least partial fusion of all neurocentral sutures. Catalogued in the collection of the Long Hao Institute of Geology and Paleontology (Hohhot, Nei Mongol Autonomous Region) and the University of Chicago (Chicago).

Etymology

Raptor, plunderer (Greek); rex, king (Greek); kriegsteini, after Roman Kriegstein, in whose honor the specimen was secured for scientific study.

Locality

Approximately 41° 20’N and 119° 40’E, collected privately in the border area between Liaoning Province and the Nei Mongol Autonomous Region of the People’s Republic of China.

Horizon and associations

Lujiatun Beds of the Yixian Formation, comprising a tuffaceous fluvial facies of the Jehol Group with its well known Jehol Biota that includes the teleost Lycoptera and pelecypods, which were found in association with the holotypic skeleton (16). The matrix around the fossil is light green, massive, poorly sorted, tuffaceous, micaceous sandstone with fibrous gypsum. The light-colored, uncrushed bones were buried for the most part in articulation. The absence of laminated, fine-grained sediment or conchostracans characterizes the Lujiatun Beds of the Yixian Formation, dated to the late Early Cretaceous (Barremian-Aptian, ca. 125 Ma).

Diagnosis

Basal tyrannosauroid with a narrow accessory pneumatic fossa within the antorbital fossa dorsal to the maxillary fenestra, jugal suborbital ramus of particularly narrow depth (transverse width approximately 60% vertical depth), and absence of a vertical crest on the iliac
blade dorsal to the acetabulum.