Plio-Pleistocene Megalonychid Sloths of North America
Plio-Pleistocene Megalonychid Sloths of North America
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北美上更新世巨齿树懒
DOI：
10.58782/flmnh.inzu2148
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发表时间：
1968
期刊：
影响因子：
--
通讯作者：
S. Webb
中科院分区：
文献类型：
--
作者：
S. Hirschfeld;S. Webb
虽然地懒出现在南美洲的Mustersan（始新世晚期），但直到Hemphillian（上新世中期）才在北美发现，当时出现了三个属，其中两个是巨爪类。现在看来，巨爪龙属在当时广泛分布于北美。最原始的是M。mathisi，新种，来自Mehrtens组上部，默塞德公司，加州。M的其他材料。来自苏族公司上蛇溪通道的curvidens Matthew，内布拉斯加州，不同之处在于其较短的颊齿和较窄的犬齿从后来的物种。同样，我们还收集了一批晚Blancan（早更新世）M.来自兰德尔公司的西塔峡谷的细口鱼科普，得克萨斯州，表现出小的颅骨，牙齿和足的差异，从典型的晚更新世物种的巨爪。M. leptonyx（Marsh）是一个可疑的名称。综述了巨爪类的一般特征，分析了其齿系的巨大变异性。北美最早的巨爪类是一个新的属和种，Pliometanastes protistus，来自Alachua Co.，麦基希农场的早期Hemphillian沉积物。佛罗里达。描述了这一新属的相对完整的材料。另一个来自新墨西哥州的新物种，？P. galushai和其他来自北美西部的记录。该属与巨爪龙或任何西印度巨爪龙没有特别的关系，但起源于一些中新世-上新世的种群，这些种群都是由它们产生的。
Although ground sloths appear in South America in Mustersan (late Eocene) time, they are not found in North America until the Hemphillian (middle Pliocene) when three genera appear, two of them megalonychids. It now appears that the genus Megalonyx was widely distributed through North America by that time. The most primitive is M. mathisi, new species, from the upper Mehrtens formation, Merced Co., California. Additional material of M. curvidens Matthew from the Upper Snake Creek channels of Sioux Co., Nebraska, differs in its shorter cheek teeth and narrower caniniforms from later species. Likewise a fine collection of late Blancan (early Pleistocene) M. leptostomus Cope from Cita Canyon, Randall Co., Texas, exhibits small cranial, dental and podial differences from typical late Pleistocene species of Megalonyx. M. leptonyx (Marsh) is a nomen dubium. The general features of Megalonyx are reviewed and the great variability of its dentition is analyzed. The earliest megalonychid from North America is a new genus and species, Pliometanastes protistus, from early Hemphillian deposits at McGehee Farm, Alachua Co., Florida. Relatively complete material of this new genus is described. Another new species from New Mexico, ?P. galushai, and other records from western North America are presented. The genus bears no special relationship to Megalonyx nor to any of the West Indian megalonychids, but stems from some Mio-Pliocene stock that gave rise to all of these.