Editing Scute (section)

==Birds==

The [[tarsometatarsus]] and toes of most birds are covered in two types of scales. Large scutes run along the dorsal side of the tarsometatarsus and toes, whereas smaller scutellae run along the sides. Both structures share histochemical homology with reptilian scales; however, work on their evolutionary development has revealed that the scales in bird feet have secondarily evolved via suppression of the feather-building genetic program.<ref name="SawKnap2003">Sawyer, R.H., Knapp, L.W. 2003. Avian Skin Development and the Evolutionary Origin of Feathers. J. Exp. Zool (Mol Dev Evol) 298B:57–72.</ref><ref name="Sawyeretal05">{{cite journal | last1 = Sawyer | first1 = R.H. | last2 = Rogers | first2 = L. | last3 = Washington | first3 = L. | last4 = Glenn | first4 = T.C. | last5 = Knapp | first5 = L.W. | year = 2005 | title = Evolutionary Origin of the Feather Epidermis | journal = Dev. Dyn. | volume = 232 | issue = 2| pages = 256–267 | doi=10.1002/dvdy.20291| pmid = 15637693 | s2cid = 44477271 | doi-access = free }}</ref><ref name="Dhouailly09">{{cite journal | last1 = Dhouailly | first1 = D | year = 2009 | title = A new scenario for the evolutionary origin of hair, feather, and avian scales | url =http://www.hal.inserm.fr/docs/00/38/16/27/PDF/inserm-00381627_edited.pdf | journal = Journal of Anatomy | volume = 214 | issue = 4| pages = 587–606 | doi=10.1111/j.1469-7580.2008.01041.x | pmid=19422430 | pmc=2736124}}</ref> Unblocking the feather suppression program results in feathers growing in place of scales along the tarsometatarsus and toes.<ref name="SawKnap2003" /><ref name="Sawyeretal05" /><ref name="Dhouailly09" /> Dinosaur species very close to the origin of birds have been shown to have had "hind wings" made of feathers growing from these areas, suggesting that the acquisition of feathers in dinosaurs was a whole-body event.<ref name="Dhouailly09" /> The bottoms of bird feet are covered in small, keeled scale-like structures known as reticulae. Evolutionary developmental studies on these scale-like structures have revealed that they are composed entirely of alpha keratin (true epidermal scales are composed of a mix of alpha and beta keratin).<ref name="Dhouailly09" /> These data have led some researchers to suggest that reticulae are in fact highly truncated feathers.<ref name="Dhouailly09" /><ref>{{cite journal | last1 = Zheng | first1 = X. | last2 = Zhou | first2 = Z. | last3 = Wang | first3 = X. | last4 = Zhang | first4 = F. | last5 = Zhang | first5 = X. | last6 = Wang | first6 = Y. | last7 = Xu | first7 = X. | year = 2013 | title = Hind wings in basal birds and the evolution of leg feathers | journal = Science | volume = 339 | issue = 6125| pages = 1309–1312 | doi=10.1126/science.1228753 | pmid=23493711| bibcode = 2013Sci...339.1309Z | citeseerx = 10.1.1.1031.5732 | s2cid = 206544531 }}</ref>