Samuels Joshua X, Meachen Julie A, Sakai Stacey A
John Day Fossil Beds National Monument, Kimberly, Oregon 97848, USA.
J Morphol. 2013 Feb;274(2):121-46. doi: 10.1002/jmor.20077. Epub 2012 Sep 13.
Members of the order Carnivora display a broad range of locomotor habits, including cursorial, scansorial, arboreal, semiaquatic, aquatic, and semifossorial species from multiple families. Ecomorphological analyses from osteological measurements have been used successfully in prior studies of carnivorans and rodents to accurately infer the locomotor habits of extinct species. This study uses 20 postcranial measurements that have been shown to be effective indicators of locomotor habits in rodents and incorporates an extensive sample of over 300 individuals from more than 100 living carnivoran species. We performed statistical analyses, including analysis of variance (ANOVA) and stepwise discriminant function analysis, using a set of 16 functional indices (ratios). Our ANOVA results reveal consistent differences in postcranial skeletal morphology among locomotor groups. Cursorial species display distal elongation of the limbs, gracile limb elements, and relatively narrow humeral and femoral epicondyles. Aquatic and semiaquatic species display relatively robust, shortened femora and elongate metatarsals. Semifossorial species display relatively short, robust limbs with enlarged muscular attachment sites and elongate claws. Both semiaquatic and semifossorial species have relatively elongate olecranon process of the ulna and enlarged humeral and femoral epicondyles. Terrestrial, scansorial, and arboreal species are characterized by having primarily intermediate features, but arboreal species do show relatively elongate manual digits. Morphological indices effectively discriminate locomotor groups, with cursorial and arboreal species more accurately classified than terrestrial, scansorial, or semiaquatic species. Both within and between families, species with similar locomotor habits converge toward similar postcranial morphology despite their independent evolutionary histories. The discriminant analysis worked particularly well to correctly classify members of the Canidae, but not as well for members of the Mustelidae or Ursidae. Results are used to infer the locomotor habits of extinct carnivorans, including members of several extinct families, and also 12 species from the Pleistocene of Rancho La Brea.
食肉目动物表现出广泛的运动习性，包括来自多个科的奔跑型、攀缘型、树栖型、半水生型、水生型和半穴居型物种。在先前对食肉动物和啮齿动物的研究中，基于骨骼测量的生态形态学分析已成功用于准确推断已灭绝物种的运动习性。本研究采用了20种颅后测量方法，这些方法已被证明是啮齿动物运动习性的有效指标，并纳入了来自100多种现存食肉动物物种的300多个个体的大量样本。我们使用一组16个功能指数（比率）进行了统计分析，包括方差分析（ANOVA）和逐步判别函数分析。我们的方差分析结果显示，不同运动类型的动物在颅后骨骼形态上存在一致差异。奔跑型物种的四肢远端伸长，肢体元素纤细，肱骨和股骨上髁相对较窄。水生和半水生物种的股骨相对粗壮、缩短，跖骨伸长。半穴居型物种的四肢相对短而粗壮，肌肉附着部位增大，爪子伸长。半水生和半穴居型物种的尺骨鹰嘴突都相对较长，肱骨和股骨上髁增大。陆生、攀缘和树栖型物种的特征主要是具有中间特征，但树栖型物种的手指确实相对较长。形态指数能够有效地区分不同的运动类型，奔跑型和树栖型物种的分类比陆生、攀缘或半水生物种更准确。无论在科内还是科间，具有相似运动习性的物种尽管有独立的进化历史，但都趋向于具有相似的颅后形态。判别分析在正确分类犬科动物成员方面表现特别出色，但对鼬科或熊科成员的分类效果则不太理想。研究结果用于推断已灭绝食肉动物的运动习性，包括几个已灭绝科的成员，以及来自拉布雷亚牧场更新世的12个物种。
