Sinotyrannus kazuoensis

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Sinotyrannus (meaning "Chinese tyrant") is a genus of medium-large basal tyrannosauroid known from a single incomplete fossil specimen including a partial skull, from the Early Cretaceous of China. It is the largest known theropod from the Jiufotang Formation to date. The type species is S. kazuoensis, described by Ji et al., in 2009. The original description of Sinotyrannus proposed that it could have been the earliest tyrannosaurid due to its large size, but subsequent analyses place it as a proceratosaurid tyrannosauroid. The holotype of Sinotyrannus is KZV-001, a disarticulated partial skeleton including the front portion of the skull, three dorsal vertebrae, the incomplete ilia, three articulated manual phalanges (including an ungual), and other fragmentary bones The preserved cranial elements include the premaxilla, dentary, and anterior portions of the maxilla and nasals. The dorsal margin of the maxilla is unusually concave unlike the convex condition in tyrannosaurids. The nares are large and elliptical, supporting its relation to the Proceratosauridae. The dentary gradually curves upwards as it approaches its front edge.
Many teeth are preserved attached to the maxillae, with a roughly equal number of denticles on each side, similarly to those of tyrannosaurids. Sinotyrannus could perceivably have had a tall nasal crest like other proceratosaurids, although not enough of its nasals are preserved to be certain. The three preserved vertebrae have very tall neural spines. The proportions of the preserved manual phalanges support the idea that they belong to the second finger, and the ungual has a deep groove on each side. The ilia are mainly present as molds, with the mold of the external side of the left ilium being the most complete. The preacetabular blade is short and wide, with a massive pubic peduncle, while the postacetabular blade is longer and thinner, with a triangular ischial peduncle.
These traits of the ilia differentiate it from more advanced tyrannosauroids such as the tyrannosaurids. On the whole, the preserved remains suggest an animal with a large skull and large arms/claws for its size, similar to its relatives like Yutyrannus.
With an estimated mean size of 6.5 meters in length and 958 kg in weight based on its relative Yutyrannus, Sinotyrannus was among the largest proceratosaurids known, repudiating the previously presumed trend that tyrannosauroids gradually increased in size throughout the Cretaceous period from small basal forms like Dilong and Guanlong to advanced apex predators such as Tyrannosaurus. Reply

[DinoFan83]

Sinotyrannus skeletal by Daniel Barrera.

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Sinotyrannus size chart by Daniel Barrera.

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Sinotyrannus life restoration by Sean Fox.

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