{"title":"Mylodon darwinii (Owen, 1840): hair morphology of an extinct sloth","authors":"","doi":"10.1007/s00435-024-00652-9","DOIUrl":null,"url":null,"abstract":"<h3>Abstract</h3> <p><em>Mylodon darwinii</em> is an extinct terrestrial species of sloth with a wide fossil record in South America, the record of the skin and hairs found from "La Cueva del Milodón", Chile. More than a century after the first studies on its hair, we aimed to redescribe the morphological characteristics of the hairs of <em>M. darwinii</em> by applying modern protocols of trichology and microscopy. Hair patterns were also compared with those of two other extinct species of sloths available in the literature. Hairs from mummified specimen housed in Museo de La Plata (Argentina) were analyzed through light and scanning electron microscopy to identify their cuticular and medullary patterns. Guard hairs lack medulla and have a wavy cuticle with irregular scale orientation, while underhairs have an amorphous cuticle pattern and no medulla. Hence, the former ones help in the diagnosis of the hair morphology of the species, while the latter ones do not. Differences found in the final product of each microscopy technique are discussed and should be considered in future research. The outcomes presented herein are a step further toward the understanding of evolutionary processes within Xenarthra, providing important data for such a poorly studied group that has only been recorded in Central and South America.</p>","PeriodicalId":24027,"journal":{"name":"Zoomorphology","volume":"83 1","pages":""},"PeriodicalIF":1.1000,"publicationDate":"2024-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Zoomorphology","FirstCategoryId":"99","ListUrlMain":"https://doi.org/10.1007/s00435-024-00652-9","RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"ANATOMY & MORPHOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Mylodon darwinii is an extinct terrestrial species of sloth with a wide fossil record in South America, the record of the skin and hairs found from "La Cueva del Milodón", Chile. More than a century after the first studies on its hair, we aimed to redescribe the morphological characteristics of the hairs of M. darwinii by applying modern protocols of trichology and microscopy. Hair patterns were also compared with those of two other extinct species of sloths available in the literature. Hairs from mummified specimen housed in Museo de La Plata (Argentina) were analyzed through light and scanning electron microscopy to identify their cuticular and medullary patterns. Guard hairs lack medulla and have a wavy cuticle with irregular scale orientation, while underhairs have an amorphous cuticle pattern and no medulla. Hence, the former ones help in the diagnosis of the hair morphology of the species, while the latter ones do not. Differences found in the final product of each microscopy technique are discussed and should be considered in future research. The outcomes presented herein are a step further toward the understanding of evolutionary processes within Xenarthra, providing important data for such a poorly studied group that has only been recorded in Central and South America.
摘要 Mylodon darwinii 是一种已灭绝的陆生树懒物种，在南美洲有广泛的化石记录，其皮肤和毛发的记录发现于智利的 La Cueva del Milodón。在对达尔文树懒的毛发进行首次研究一个多世纪后，我们采用现代毛发学和显微镜技术重新描述了达尔文树懒毛发的形态特征。我们还将达尔文树懒的毛发形态与文献中另外两种已灭绝树懒的毛发形态进行了比较。通过光镜和扫描电子显微镜分析了保存在阿根廷拉普拉塔博物馆的木乃伊标本上的毛发，以确定它们的角质层和髓质模式。护毛缺乏髓质，角质层呈波浪状，鳞片方向不规则，而底毛的角质层形态无定形，没有髓质。因此，前者有助于诊断物种的毛发形态，而后者则没有帮助。本文讨论了每种显微镜技术的最终产品中发现的差异，这些差异应在今后的研究中加以考虑。本文介绍的结果为了解栉水母（Xenarthra）的进化过程又迈进了一步，为这个仅在中美洲和南美洲有记录的研究较少的类群提供了重要数据。
期刊介绍：
The journal publishes original research papers, reviews and method papers. While reviews should be designed as comparative surveys, summarizing the current knowledge from an evolutionary perspective, method papers should present new approaches or reviews on methods used in animal morphology. The research papers should be based on morphological investigation of invertebrates and vertebrates at the macroscopic, microscopic and ultrastructural level, including embryological studies.
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