Describer

Ji Q., Ji, S.A. & Zhang 2009

Time

Cretaceous Early

Classification

Saurischia Theropoda Tyrannosauria ?Tyrannosauridae

Diet

Carnivore

Fossilsite

Jiufotang Formation, Dachengzi town, Kazuo County, Liaoning, China

Length

9~10 meter

Info

Abstract

An incomplete theropod skeleton including partial skull, mandibles, ilia was collected frtom Early Cretaeous Jiufotang Formation of Kazuo County, western Liaoning Province. It can be estimated that this theropod may reach 9~10 meters in total length. It should be classified whitin Tyrannosauroidae by its tall premaxillary body, median vertical ridge on the external surface of ilium. It differs from the Late Cretaceous tyrannosaurids by much large extarnal naris, sligthly concave anterior portion of maxiallary dorsal margin, maxillary fenestra reaching past the rostral margin of antiorbital fossa but keeping apart from the ventral margin of antiorbital fossa. Thus, Sinotyrannus kazuoensis gen. et sp. nov. is erected, perhaps representing the earliest member of Tyrannosauridae. This is the largest known pre-Late Cretaceous tyrannosauroid, and also the largest theropod from the Jehol Biota of western Liaoning and the adjecent regions. The discovery of this taxon not only suggest that East Asia should be one of the most important evolutionary centers of tyrannosauroids, but also provides the significant evidences for studying the origin of Tyrannosauridae, and the composition and ecosystem of the Jehol Biota.

Holotype

KZV-001, the disarticulated skeleton including the anterior portions of skull and mandibles, three articulated dorsal vertebrae, several dorsal ribs, incomplete ilia, partial manual phalanges, and some other fragmentary bones. This specimen is housed in the Bureau of Land and Resources of Kazuo County, Liaoning Province.

Etymology

The generic name is composed of the Latin \\\\\\\"SIno-\\\\\\\" (an acient name of China), and Greek \\\\\\\"tyrannus\\\\\\\"(tyrant). The specific name is after \\\\\\\"Kazuo\\\\\\\", the county in which the type specimen was discovered.

Locality and horizon

Dachengzi town, Kazuo County, western Liaoning Province, China; lower part of Jiufotang Formation, Early Cretaceous

Diagnosis

Large tyrannosauroid roughly 9~10 meters long, much longer than other Late Jurassic or Early Cretaceous tyrannosauroids. This new genus falling into the size of Late Cretaceous tyrannosauroids, but differing from those in the following combined characters: proportionally large external naris; anterior portion of the dorsal amrgin of maxilla slightly concave; maxillary fenestra reaching past the rostral marginof the antorbital fossa; the preacetaqbular blade of ilium comparatively short, and lacking the ventrally expanded anterior hook.

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