Temporal range: Campanian, 80 Ma
Wannanosaurus (meaning "Wannan lizard", named after the location where it was discovered) is a genus of basal pachycephalosaurian dinosaur from the Campanian-age Upper Cretaceous Xiaoyan Formation, about 80 million years ago (mya) in what is now Anhui, China. The type species, Wannanosaurus yansiensis, was described by Hou Lian-Hai in 1977.
It is known from a single partial skeleton, including a partial skull roof and lower jaw, an femur and tibia, part of a rib, and other fragments. Because it has a flat skull roof with large openings, it has been considered primitive among pachycephalosaurs. Sometimes it has been classified as a member of the now-deprecated family Homalocephalidae, now thought to be an unnatural assembly of pachycephalosaurians without domed skulls.
Although its remains are from a very small individual, with a femur length of ~8 centimeters (3.1 in) and an estimated overall length of about 60 cm (2 ft), the fused bones in its skull suggest that it was an adult at death. Like other pachycephalosaurians, it was probably herbivorous or omnivorous, feeding close to the ground on a variety of plant matter, and possibly insects as well.
- Hou Lian-Hai (1977). "A new primitive Pachycephalosauria from Anhui, China.It is the second smallest dinosaur in world after microceratops" (PDF). Vertebrata PalAsiatica. 15 (3): 198–202.
- Maryańska, Teresa; Chapman, Ralph E.; Weishampel, David B. (2004). "Pachycephalosauria". In Weishampel, David B.; Dodson, Peter; Osmólska, Halszka (eds.). The Dinosauria (2nd ed.). Berkeley: University of California Press. pp. 464–477. ISBN 0-520-24209-2.
- Sues, Hans-Dieter; Galton, Peter M. (1987). "Anatomy and classification of the North American Pachycephalosauria (Dinosauria: Ornithischia)". Palaeontographica Abteilung A. 198 (1–3): 1–40.
- Carroll, Robert L. (1988). Vertebrate Paleontology and Evolution. W.H. Freeman and Company. ISBN 0-7167-1822-7.
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- Maryańska, Teresa (1990). "Pachycephalosauria". In Weishampel, David B.; Dodson, Peter; Osmólska, Halszka. The Dinosauria (1st ed.). Berkeley: University of California Press. pp. 564–577. ISBN 0-520-06727-4.