Claorhynchus

Claorhynchus Temporal range: Late Cretaceous
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Sauropsida
Superorder:	Dinosauria
Order:	Ornithischia
Suborder:	Cerapoda
Infraorder:	uncertain
Genus:	Claorhynchus Cope, 1892
Binomial name
Claorhynchus trihedrus Cope, 1892

Claorhynchus (meaning "broken beak", as it is based on broken bones from the snout region) is a dubious genus of ornithischian dinosaur with a confusing history behind it. It has been considered to be both a hadrosaurid and a ceratopsid, sometimes the same as Triceratops, with two different assignments as to discovery formation and location, and what bones make up its type remains.

History

Paleontologist and naturalist Edward Drinker Cope described what he interpreted as an "agathaumid" (horned dinosaur)'s rostral bone and predentary AMNH 3978, which he said came from the Laramie Formation of Montana.^[1] It was soon thought to be a hadrosaurid, though.^[2][3] In their influential monograph, Richard Swann Lull and Nelda E. Wright regarded the genus as a dubious type of hadrosaurid, based on premaxillae and a predentary.^[4]

This opinion stood until the work of Michael K. Brett-Surman, who stated in his dissertation that, having rediscovered and reexamined the material with Douglas A. Lawson, it was most likely part of a ceratopsid's neck frill, probably part of the squamosal of Triceratops.^[5] This information reached Donald F. Glut's series of dinosaur encyclopedias in a confusing form; its entry states that a squamosal and tooth from South Dakota were referred to the genus, and these are what Brett-Surman and Lawson identified, keeping the supposed beak remains separate.^[6] Additionally, other major reviews have left the genus as an indeterminate hadrosaurid.^[7][8]

Thus, there are two views: one that this genus represents a piece of Triceratops frill, and one that it is a dubious hadrosaurid. The photograph of the specimen in Glut's encyclopedia shows a mass of thick polygonal fragments. At any rate, no modern sources consider its material to permit classification farther than to family, and so it is mostly a historical curiosity at this point.

References

1. ^ Cope, E.D. (1892). Fourth note on the Dinosauria of the Laramie. The American Naturalist 26:756-758.
2. ^ Hatcher, J.B. (1902). The genus and species of the Trachodontidae (Hadrosauridae, Claosauridae) Marsh. Annals of the Carnegie Museum 14(1):377-386.
3. ^ Hatcher, J.B., Marsh, O.C., and Lull, R.S. (1907). The Ceratopsia. Government Printing Office:Washington, D.C., 300 pp. ISBN 0405127138
4. ^ Lull, R.S., and Wright, N.E. (1942). Hadrosaurian Dinosaurs of North America. Geological Society of America Special Paper 40:1-242.
5. ^ Brett-Surman, M.K. 1989(1988). A revision of the Hadrosauridae (Reptilia: Ornithischia) and their evolution during the Campanian and Maastrichtian. Ph.D. dissertation, George Washington University:Washington, D.C.. pp.1-272.
6. ^ Glut, D.F. (1997). "Claorhynchus". Dinosaurs: The Encyclopedia. McFarland & Company. p. 299.. ISBN 0-89950-917-7. 
7. ^ Weishampel, D.B., and Horner, J.R. (1990). Hadrosauridae. In: Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.). The Dinosauria. University of California Press:Berkeley, 534-561. ISBN 0-520-24209-2
8. ^ Horner, J.R., Weishampel, D.B., and Forster, C.A. (2004). Hadrosauridae. In: Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.). The Dinosauria (second edition). University of California Press:Berkeley, 438-463. ISBN 0-520-06727-4.

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