| Siamotyrannus Temporal range: Early Cretaceous, 135 Ma |
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|---|---|
| Illustration of the pelvic bones and tail vertebrae | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Superorder: | Dinosauria |
| Order: | Saurischia |
| Suborder: | Theropoda |
| Node: | Avetheropoda |
| Infraorder: | †Carnosauria |
| Genus: | †Siamotyrannus Buffetaut, Suteethorn & Tong, 1996 |
| Species: | †S. isanensis Buffetaut et al., 1996 |
Siamotyrannus (meaning "Siamese Tyrant") is a genus of theropod dinosaur from the early Cretaceous (Aptian-Albian). It is known from a partial skeleton which includes part of the pelvis, the sacrum, and a number of vertebrae. The fossils were found in 1993 by Somchai Traimwichanon in the Sao Khua Formation of northeastern Thailand.[1] As evidenced by its name, it was originally thought to be a tyrannosauroid, though due to lacking some of the primary tyrannosauroid synapomorphies that define the clade, its position here is not certain.[2] Some analyses have categorized Siamotyrannus as a primitive carnosaur rather than a basal tyrannosauroid, and it has several features that may determine it to be an allosaurid or a sinraptorid. Little is known of the appearance of the animal, though the known elements suggest it was approximately 6.5 meters long.[3]