Temporal range: Late Triassic
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Allokotosauria
Order: Trilophosauria
Family: Trilophosauridae
Genus: Tricuspisaurus
Robinson, 1957
Type species
Tricuspisaurus thomasi
Robinson, 1957

Tricuspisaurus is an extinct genus of trilophosaur. Fossils are known from the Ruthen Quarry in Glamorgan, Wales. Like some other trilophosaurs, it has an edentulous, or toothless beak. Tricuspisaurus gets its name from its heterodont dentition, which includes tricuspid teeth, or teeth with three cusps. The type species, T. thomasi, was named in 1957 along with the closely related trilophosaur Variodens inopinatus from Somerset, England.[1]

Although originally classified as a trilophosaur, Tricuspisaurus was reclassified as a procolophonid in 1993 by paleontologists Hans-Dieter Sues and Paul E. Olsen.[2] This was due to similarities between its tricuspid teeth and those of the newly described procolophonid Xenodiphyodon. Along with Tricuspisaurus, Variodens and Trilophosaurus jacobsi were also considered to be procolophonids.[3] However, more recently described cranial material from T. jacobsi indicates that it is a trilophosaur, which suggests that Tricuspisaurus is also a trilophosaur rather than a procolophonid.[4]


  1. Robinson, P.L. (1957). "An unusual sauropsid dentition". Zoological Journal of the Linnean Society. 43 (291): 283–293. doi:10.1111/j.1096-3642.1957.tb01554.x.
  2. Sues, H.-D.; Olsen, P.E. (1993). "A new procolophonid and a new tetrapod of uncertain, possibly procolophonian affinities from the Upper Triassic of Virginia". Journal of Vertebrate Paleontology. 13 (3): 282–286. doi:10.1080/02724634.1993.10011510.
  3. Fraser, N.C. (1997). "Assemblages of small tetrapods from British Late Triassic fissure deposits". In Fraser, N.C. and Sues, H.-D. (eds.). In the Shadow of the Dinosaurs: Early Mesozoic Tetrapods. Cambridge and New York: Cambridge University Press. pp. 214–225. ISBN 9780521458993.
  4. Heckert, A.B.; Lucas, S.G.; Rinehart, L.F.; Spielmann, J.A.; Hunt, A.P.; Kahle, R. (2006). "Revision of the archosauromorph reptile Trilophosaurus, with a description of the first skull of Trilophosaurus jacobsi, from the Upper Triassic Chinle Group, West Texas, USA". Palaeontology. 49 (3): 621–640. doi:10.1111/j.1475-4983.2006.00556.x.

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