Editing Xenarthra (section)

===Vision===
Xenarthrans have been determined to have single-color vision. [[Polymerase chain reaction|PCR]] analysis determined that a mutation in a stem xenarthran led to long-wavelength sensitive-cone (LWS) [[monochromacy]] (single color vision), common in nocturnal, aquatic and subterranean mammals.<ref name="Emerling2015">{{Cite journal |last1=Emerling |first1=Christopher A. |last2=Springer |first2=Mark S. |date=2015-02-07 |title=Genomic evidence for rod monochromacy in sloths and armadillos suggests early subterranean history for Xenarthra |journal=Proceedings of the Royal Society B: Biological Sciences |volume=282 |issue=1800 |pages=20142192 |doi=10.1098/rspb.2014.2192 |issn=0962-8452 |pmc=4298209 |pmid=25540280}}</ref> Further losses led to rod monochromacy in a stem [[Cingulata|cingulate]] and a stem [[pilosa]]n, pointing to a subterranean ancestry; the ancestors of Xenarthra had the reduced eyesight characteristic of vertebrates that live underground.<ref name="Emerling2015" /> Some authorities state that xenarthrans lack a functional [[pineal gland]]; pineal activity is related to the perception of light.<ref>{{cite book|last1=Axelrod|first1=J.|url=https://books.google.com/books?id=VH7SBwAAQBAJ&q=pineal+regularly+present+Xenarthra&pg=PA62|title=The Pineal Gland and its Endocrine Role|date=December 2013|publisher=Springer |isbn=9781475714517|via=Google Books}}{{full citation needed|date=June 2019}}</ref>