Flightlessness and long bone allometry in Palaeognathiformes and Sphenisciformes
Flightlessness and long bone allometry in Palaeognathiformes and Sphenisciformes
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DOI：
10.1163/156854297x00175
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发表时间：
1997-05-01
期刊：
影响因子：
--
通讯作者：
Casinos, A
中科院分区：
文献类型：
--
作者：
Cubo, J;Casinos, A
仅有的两个主要类群--古陆亚目和海鞘亚目已经丧失了飞行能力。然而，这种不能飞行的后果是完全不同的。虽然古鼻目动物都是奔跑的鸟类，但水栖类动物适应于游泳。为了研究小腿和翼骨的形态，测量了肱骨、尺骨、尺骨、桡骨、股骨、胫颧骨和颧骨的长度、矢状径、横径和面积二阶矩。对14种古颌目的33个标本和7个种的11个标本进行了研究。来自其他鸟类目的几种非飞行物种也被考虑在内。以体重为自变量，计算各参数的回归方程。并计算每根骨的矢状径/横径之比。大多数关联式与等轴测条件有很大不同。从力学角度来看，最有趣的结果是，腿部长骨面积的第二个力矩总是具有较强的正异速生长，而在翅膀长骨的情况下，伸缩显示出较高的负异速生长。在生物统计学上，蝶形目动物显示出恒定的翅膀长骨形态，横径比矢状径大得多。相比之下，古颌形目的翼骨形态变化很大，影响其长度和直径。
Palaeognathiformes and Sphenisciformes are the only two major taxa that have lost the capacity for flying. Nevertheless, the consequences of this flightlessness are completely different. While Palaeognathiformes are all running birds, Sphenisciformes are adapted to swimming. To study the morphology of leg and wing bones, length, sagittal and transverse diameters and second moment of area of humerus, ulna, radius, femur, tibiotarsus and tarsometatarsus were measured. Thirty-three specimens from fourteen species of Palaeognathiformes and eleven specimens from seven species of Sphenisciformes were studied. Several non-flying species from other avian orders were also considered. Regressions of all these parameters were calculated with body mass as the independent variable. For each bone, the ratio sagittal diameter/transverse diameter was also calculated. Most of the correlations are significantly different from the isometric condition. From a mechanical point of view, the most interesting result is that the second moment of area of the leg long bones always scales with strong positive allometry, whereas in the case of the wing long bones, the scaling shows high negative allometry. Biometrically, Sphenisciformes display a constant wing long bone morphology, with transverse diameters much larger than sagittal. In contrast, Palaeognathiformes present a highly variable morphology of the wing bones, affecting length and diameters.