Feature scales are enlarged scales found on various reptiles. Despite their close resemblance to osteoderms, they have no boney component to them.1 Examples of reptiles that are known to possess feature scales are iguanas,2 and many non-avian dinosaurs such as Carnotaurus,1 Brachylophosaurus,3 diplodocids,4 and various ceratopsians.5 The term was coined by Australian paleontologist Phil R. Bell in 2012 in reference to the midline scutes of the hadrosaurid Saurolophus.6

Feature scales are distinguished from basement scales (typical, small scales that make up most of the overall scales), by their notable size difference, being significantly wider and taller.6
References
References
- Czerkas, Stephen A.; Czerkas, Sylvia J. (1997). "The Integument and Life Restoration of Carnotaurus". In Wolberg, D. I.; Stump, E.; Rosenberg, G. D. (eds.). Dinofest International. Academy of Natural Sciences, Philadelphia. pp. 155–158.
- "Anoles, Iguanas, and Relatives: Iguanidae | Encyclopedia.com". www.encyclopedia.com. Retrieved 2021-03-31.
- Murphy, N.L.; Trexler, D.; Thompson, M. (2006). ""Leonardo," a mummified Brachylophosaurus from the Judith River Formation". In Carpenter, K. (ed.). Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs. Indiana University Press. pp. 117–133. ISBN 0-253-34817-X.
- Czerkas, S.A. (1993). "Discovery of dermal spines reveals a new look for sauropod dinosaurs". Geology. 20 (12): 1068–1070. Bibcode:1992Geo....20.1068C. doi:10.1130/0091-7613(1992)020<1068:dodsra>2.3.co;2.
- Bell, Phil R.; Hendrickx, Christophe; Pittman, Michael; Kaye, Thomas G.; Mayr, Gerald (August 12, 2022). "The exquisitely preserved integument of Psittacosaurus and the scaly skin of ceratopsian dinosaurs". Communications Biology. 5 (1): 809. doi:10.1038/s42003-022-03749-3. ISSN 2399-3642. PMC 9374759. PMID 35962036.
- Bell, P.R. (2012). "Standardized Terminology and Potential Taxonomic Utility for Hadrosaurid Skin Impressions: A Case Study for Saurolophus from Canada and Mongolia". PLOS ONE. 7 (2) e31295. Bibcode:2012PLoSO...731295B. doi:10.1371/journal.pone.0031295. PMC 3272031. PMID 22319623.
- Samuelson, Phillip (1995-06-01), "The Lizard King", Reptiles Magazine, 3 (2): 64–84, Bibcode:1996SciAm.274f..26M, doi:10.1038/scientificamerican0696-26a