On Megatherium gallardoi (Mammalia, Xenarthra, Megatheriidae) and the Megatheriinae from the Ensenadan (lower to middle Pleistocene) of the Pampean region, Argentina
On Megatherium gallardoi (Mammalia, Xenarthra, Megatheriidae) and the Megatheriinae from the Ensenadan (lower to middle Pleistocene) of the Pampean region, Argentina
复制标题
阿根廷潘皮亚地区 Ensenadan（下更新世至中更新世）的 Megatherium gallardoi（哺乳动物、Xenarthra、Megatheriidae）和 Megatheriinae
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
A. Scarano
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文献类型：
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作者：
D. Brandoni;E. Soibelzon;A. Scarano
阿根廷中新世中期至全新世早期记录了Mejuiinae（哺乳动物，Xenarthra，Mejuiidae）。只有包括几个有争议的有效性的物种的Meidium属，被确认为Pamerican地区的更新世。美洲扁角叶蝉是研究得最好的物种，经常出现在Lujanian阶的沉积物中[Equus（Amerhippus）neogeus Biozone，c. 0.13-0.08 My）。另一方面，M。gallardoi和M. silenum，均来自布宜诺斯艾利斯省Ensenadan沉积物（Mesotherium cristatum Biozone），被一些作者认为是M americanum的异名。本文的主要目的是完成对M. gallardoi，澄清其分类地位，并建立其与其他megatheriines的关系。M. gallardoi是：前上颌骨彼此不融合或与上颌骨不融合;下颌支相对较低;股骨外侧和内侧骨干边缘明显凹陷，骨干横向扩张;髌骨软骨内侧复位;肱骨和股骨强健。在解剖学和比较分析的基础上，我们提出：1）M. gallardoi为有效种; 2）标本MACN Pv 5002（M. gallardoi）为成年个体; gallardoi与M. americanum和M. altiplanicum; 4）Msilenum（阿根廷Ensenadan阶已知的另一个Mesophiinae）应被认为是nomen vanum，因为它缺乏诊断特征，无疑对应于一个幼年个体。
The Megatheriinae (Mammalia, Xenarthra, Megatheriidae) are recorded in Argentina from the middle Miocene to the early Holocene. Only the genus Megatherium, comprising several species of controversial validity, is recognized for the Pleistocene of the Pampean region. Megatherium americanum is the best studied species and occurs frequently in sediments assigned to the Lujanian stage [Equus (Amerhippus) neogeus Biozone, c. 0.13-0.08 My). On the other hand, M. gallardoi and M. silenum, both from Ensenadan sediments (Mesotherium cristatum Biozone) of Buenos Aires Province, have been considered by some authors as synonyms ofM americanum. The main goal of this contribution is to complete the description of M. gallardoi, clarify its taxonomic status, and establish its relationships with other megatheriines. The most remarkable features of M. gallardoi are: premaxillae not fused to each other or to the maxillae; mandibular ramus relatively low; femur with lateral and medial diaphyseal margins markedly concave, diaphysis expanded transversely; medial reduction of the patellar trochlea; humerus and femur robust. Based on the anatomical and comparative analysis, we propose that: 1) M. gallardoi is a valid species; 2) specimen MACN Pv 5002 (holotype of M. gallardoi) is an adult individual; 3) M. gallardoi is related to the clade formed by M. americanum and M. altiplanicum; and 4) M silenum (the other Megatheriinae known for the Ensenadan Stage of Argentina) should be considered nomen vanum because it lacks diagnostic features and corresponds undoubtedly to a juvenile individual.