Phuwiangosaurus

Phuwiangosaurus (meaning "Phu Wiang lizard") is a genus of titanosaur dinosaur from the Early Cretaceous (Valanginian-Hauterivian) Sao Khua Formation of Thailand. The type species, P. sirindhornae, was described by Martin, Buffetaut, and Suteethorn in a 1993 press release and was formally named in 1994. The species was named to honor Princess Maha Chakri Sirindhorn of Thailand, who was interested in the geology and palaeontology of Thailand, while the genus was named after the Phu Wiang area, where the fossil was discovered. Phuwiangosaurus was originally assigned to Titanosauria, but more recent studies have placed it in a more basal position within the Titanosauriformes. Phylogenetic analyses presented by D'Emic (2012), Mannion et al. (2013), and Mocho et al. (2014) resolve Phuwiangosaurus within the Euhelopodidae, alongside genera such as Euhelopus and Tangvayosaurus. Other analyses have failed to find support for such a grouping, including some finding it to be paraphyletic at the base of Somphospondyli. The type specimen of Phuwiangosaurus sirindhornae was discovered in Phu Wiang National Park in 1982, and excavated and prepared over the next several years. The specimen was described as representing a new genus and species, Phuwiangosaurus sirindhornae, by Valérie Martin, Eric Buffetaut, and Varavudh Suteethorn in 1994. The genus name refers to its discovery in Phu Wiang, and the species name honors Princess Maha Chakri Sirindhorn of Thailand for her interest in the paleontology of the country. Phuwiangosaurus sirindhornae is known from several specimens, all of which were found in the Sao Khua Formation of Thailand. The holotype, SM PW 1, is a partial skeleton of an adult individual, which consists of three cervical vertebrae, three dorsal vertebrae, ribs, a chevron, both scapulae, a coracoid, the left humerus, the left ulna, both ilia, ischia, pubes, and femora, and the left fibula. A dorsal vertebra and a caudal vertebra excavated at the same site years later probably belong to the same specimen.