Nature 250, 729 - 731 (30 August 1974); doi:10.1038/250729b0

Thegosis in herbivorous dinosaurs

RICHARD A. THULBORN

Department of Zoology, University of Queensland, St Lucia, Queensland 4067, Australia

THE name thegosis was coined by Every and Kühne¹ for the short and powerful process of tooth sharpening which is accomplished in mammals by the grinding of one tooth against another. Thegosis produces sharp-edged, planar (or curved planar) wear surfaces on the teeth. The thegosis wear facets cut straight across boundaries between dentine and enamel and are typically marked with deep parallel striations (not necessarily coincident with the maximum slope of the wear facet). In some mammals thegosis keeps certain teeth sharply honed for use as weapons (as with the canines of suids and hippopotamids); in others thegosis sharpens the teeth which deal with food (as with the carnassial apparatus in felids).

References

1.	Every, R. G., and Kühne, W. G., in Early Mammals (suppl. 1 to Zool. J. Linn. Soc., 50), edit by Kermack, D. M., and Kermack, K. A., (Academic, London and New York, 1971).
2.	Thulborn, R. A., Mems Servs. geol. Port. (in the press).
3.	Wiman, C., Palaeont. sin., C6 (n.s.), 1 (1929).
4.	Cooper, J. S., and Poole, D. F. G., J. Zool., 169, 85 (1973).
5.	Thulborn, R. A., Zool. J. Linn. Soc. (in the press).
6.	Haughton, S. H., Ann. S. Afr. Mas., 12, 343 (1924).
7.	Crompton, A. W., and Charig, A. J., Nature, 196, 1074 (1962).
8.	Thulborn, R. A., Zool. J. Linn. Soc., 49, 235 (1970).
9.	Ostrom, J. H., Bull. Am. Mus. nat. Hist., 122, 39 (1961).
10.	Hatcher, J. B., Marsh, O. C., and Lull, R. S., Monogr. U. S. geol. Surv., 49, 1 (1907).
11.	Ostrom, J. H., Postilla, No. 88, 1 (1964).
12.	Ostrom, J. H., Evolution, 20, 290 (1966).
13.	Galton, P. M., Lethaia, 6, 67 (1973).
14.	Sternberg, C. M., Bull. natn. Mus. Can., 123, 225 (1951).
15.	Thulborn, R. A., J. Zool., 164, 165 (1971).
16.	Janensch, W., Palaeontographica, suppl. 7 (3), 105 (1955).
17.	Gilmore, C. W., Bull. Dep. Geol. Univ. Alberta, 1, 1 (1924).
18.	Brown, B., and Schlaikjer, E. M., Ann. N.Y. Acad. Sci., 40, 133 (1940).
19.	Owen, R., Odontography (Hippolyte Baillière, London, 1840–1845).
20.	Gilmore, C. W., Proc. U. S. natn. Mus., 36, 197 (1909).
21.	Sternberg, C. M., J. Paleont., 14, 481 (1940).
22.	Osborn, H. F., Am. Mus. Novit., No. 144, 1 (1924).
23.	Russell, L. S., Univ. Toronto Stud. geol. Ser., 43, 1 (1940).
24.	Gilmore, C. W., Bull. U.S. natn. Mus., 89, 1 (1914).