Hamrick M W, Rosenman B A, Brush J A
Department of Anthropology, Kent State University, Ohio 44240, USA.
Am J Phys Anthropol. 1999 Jul;109(3):397-413. doi: 10.1002/(SICI)1096-8644(199907)109:3<397::AID-AJPA8>3.0.CO;2-9.
A comparative morphometric analysis of isolated proximal and intermediate phalanges attributed to the paromomyids Ignacius graybullianus and Phenacolemur simonsi was undertaken to test the hypothesis that these fossil phalanges exhibit evidence of a dermopteran-like interdigital patagium. Linear dimensions were collected for the fossil phalanges and a comparative sample of associated proximal and intermediate phalanges representing extant tree squirrels, tree shrews, dermopterans (colugos), gliding rodents and marsupials, and prosimian primates. Quantitative data indicate that the proximal and intermediate phalanges of paromomyids are most similar in their overall shape to those of the dermopteran Cynocephalus. The proximal phalanges of paromomyids and colugos possess well-developed flexor sheath ridges and broad, high shafts, whereas the intermediate phalanges of these taxa are most similar to one another in their trochlear morphology. Discriminant analysis indicates that all of the paromomyid intermediate phalanges resemble those from colugo toes more so than those from colugo fingers. Moreover, the relative length and midshaft proportions of both the proximal and intermediate phalanges of paromomyids closely resemble those of several squirrels that lack an interdigital patagium. The following conclusions are drawn from this study: 1) paromomyids share a number of derived phalangeal features with modern dermopterans that may be indicative of a phylogenetic relationship between them, 2) existing intermediate phalanges of paromomyids are inconsistent with the "mitten gliding" hypothesis because they do not possess the distinctive length and midshaft proportions characteristic of colugo manual intermediate phalanges, and 3) paromomyids share with colugos and the scaly-tailed squirrel Anomalurus several aspects of phalangeal morphology functionally related to frequent vertical clinging and climbing on large-diameter arboreal supports.
对归属于副鼠科的格雷布尔伊格那修斯鼠（Ignacius graybullianus）和西蒙氏 Phenacolemur 鼠（Phenacolemur simonsi）的分离近端指骨和中间指骨进行了比较形态测量分析，以检验这些化石指骨是否表现出类似皮翼目动物指间翼膜的证据这一假设。收集了化石指骨的线性尺寸以及一个比较样本，该样本包含现存松鼠、树鼩、皮翼目动物（鼯猴）、滑翔啮齿动物和有袋动物以及原猴亚目灵长类动物的相关近端指骨和中间指骨。定量数据表明，副鼠科的近端指骨和中间指骨在整体形状上与皮翼目动物鼯猴（Cynocephalus）的最为相似。副鼠科和鼯猴的近端指骨具有发育良好的屈肌鞘嵴和宽阔、高大的骨干，而这些类群的中间指骨在滑车形态上彼此最为相似。判别分析表明，所有副鼠科的中间指骨与鼯猴脚趾的中间指骨比与鼯猴手指的更为相似。此外，副鼠科近端指骨和中间指骨的相对长度和骨干比例与几种没有指间翼膜的松鼠非常相似。从这项研究得出以下结论：1）副鼠科与现代皮翼目动物共有一些衍生的指骨特征，这可能表明它们之间存在系统发育关系；2）副鼠科现有的中间指骨与“手套滑翔”假设不一致，因为它们不具备鼯猴手部中间指骨特有的独特长度和骨干比例；3）副鼠科与鼯猴和鳞尾松鼠（Anomalurus）在指骨形态的几个方面具有功能相关性，这些方面与在大直径树木支撑物上频繁垂直攀爬有关。
