Temporal range: Early Cretaceous, 125.45–112.6 Ma
"Sinopliosaurus" fusuiensis by PaleoGeek.png
Speculative life restoration
Scientific classification

"Sinopliosaurus" fusuiensis
Hou, Yeh & Zhao, 1975

"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.[1] 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.[2] Other spinosaurid teeth from indeterminate forms have been reported from the formation, but remain undescribed.[3]


Tooth (third from left) compared to those of other Asian spinosaurs

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.[2]


"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.[4][5] 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.[6][7]


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.[3][8]


  1. ^ Hou, L., Yeh, H. and Zhao, X. (1975). Fossil reptiles from Fusui, Kwangshi. Vertebrata PalAsiatica 13; 24-33
  2. ^ a b Buffetaut, Eric; Suteethorn, Varavudh; Tong, Haiyan; Amiot, Romain (2008-09-01). "An Early Cretaceous spinosaurid from southern China". Geological Magazine. 145 (5): 745–748. Bibcode:2008GeoM..145..745B. doi:10.1017/S0016756808005360.
  3. ^ a b MO, JINYOU; Buffetaut, Eric; Tong, Haiyan; Amiot, Romain; Cavin, Lionel; Cuny, Gilles; Suteethorn, Varavudh; SUTEETHORN, SURAVECH; JIANG, SHAN (2015-07-02). "Early Cretaceous vertebrates from the Xinlong Formation of Guangxi (southern China): A review". Geological Magazine. -1 (1): 1–17. Bibcode:2016GeoM..153..143M. doi:10.1017/S0016756815000394.
  4. ^ Sales, Marcos A. F.; Schultz, Cesar L. (2017-11-06). "Spinosaur taxonomy and evolution of craniodental features: Evidence from Brazil". PLOS ONE. 12 (11): e0187070. Bibcode:2017PLoSO..1287070S. doi:10.1371/journal.pone.0187070. ISSN 1932-6203. PMC 5673194. PMID 29107966.
  5. ^ William Elliott HONE, David; Richard HOLTZ, Thomas (2017-06-01). "A Century of Spinosaurs - A Review and Revision of the Spinosauridae with Comments on Their Ecology". Acta Geologica Sinica - English Edition. 91 (3): 1120–1132. doi:10.1111/1755-6724.13328.
  6. ^ Hasegawa, Y; Buffetaut, Eric; Manabe, M; Takakuwa, Yuji (2003-03-01). "A possible spinosaurid tooth from the Sebayashi Formation (Lower Cretaceous), Gunma, Japan". Bulletin of the Gunma Museum of Natural History. 7: 1–5.
  7. ^ Katsuhiro, Kubota; Takakuwa, Yuji; Yoshikazu, Hasegawa (2017-03-31). "Second discovery of a spinosaurid tooth from the Sebayashi Formation (Lower Cretaceous), Kanna Town, Gunma Prefecture, Japan". Bulletin of the Gunma Museum of Natural History. 01.
  8. ^ Amiot, R.; Buffetaut, E.; Lécuyer, C.; Wang, X.; Boudad, L.; Ding, Z.; Fourel, F.; Hutt, S.; Martineau, F.; Medeiros, A.; Mo, J.; Simon, L.; Suteethorn, V.; Sweetman, S.; Tong, H.; Zhang, F.; Zhou, Z. (2010). "Oxygen isotope evidence for semi-aquatic habits among spinosaurid theropods". Geology. 38 (2): 139–142. Bibcode:2010Geo....38..139A. doi:10.1130/G30402.1.