"Sinopliosaurus" fusuiensis

"Sinopliosaurus" fusuiensis is a species of spinosaurid theropod dinosaur from the Early Cretaceous Xinlong Formation of Guangxi Province, southern China. It is known only from teeth that were initially identified as those of a pliosauroid, but are now known to have come from an animal similar to Siamosaurus.

History of research 

In 1975, five fossil teeth were described by Chinese palaeontologists Hou Lian-Hai, Yeh Hsiang-K'uei, and Zhao Xi-Jin. The specimens were collected from the Xinlong Formation of the Guangxi Province in southern China, and assigned by Hou and colleagues to a new species of Sinopliosaurus, a pliosauroid known only from limb elements found in the Early Jurassic. A 2008 paper by Eric Buffetaut and colleagues referred the four of the original specimens (one was not found in the museum collection) to a new species of spinosaurid dinosaur. Other spinosaurid teeth from indeterminate forms have been reported from the formation, but remain undescribed.

Description 

Out of the four teeth referred to "S". fusuiensis, three were in a bad state of preservation, therefore the species description was based on the most intact specimen (IVPP V 4793). It is partially deformed and missing the uppermost part of the tip, the crown of the tooth is 6.9 cm (2.7 in) long, measuring 1.3 cm by 1.65 cm (0.5 in by 0.6 in) at its base. A distinct series of ridges are present along the length of the crown, with the gaps between them having fine wrinkle-like structures; these features have been observed in spinosaurid teeth recovered from Japan and Thailand. The most close resemblance is to the teeth of Siamosaurus from the Sao Khua Formation in Thailand.

Classification 
"Sinopliosaurus" fusuiensis is difficult to clearly distinguish from other cretaceous spinosaurids like Siamosaurus, due to the uncertainties of naming new theropod taxa using isolated teeth. Until skull material is found associated with teeth from an Asian spinosaur, a more precise classification of the various teeth found in China, Thailand, and Japan cannot be attained.

Palaeoecology 
In 2010, an Isotope analysis on spinosaur teeth by Romain Amiot and colleagues found that the Xinlong Formation spinosaurs had semi-aquatic habits similar to those of water-dwelling turtle species.

References

Category:Spinosaurids
Category:Early Cretaceous dinosaurs of Asia
Category:Paleontology in Guangxi