Functional specialization and ontogenetic scaling of limb anatomy in Alligator mississippiensis
Functional specialization and ontogenetic scaling of limb anatomy in Alligator mississippiensis
复制标题
DOI：
10.1111/j.1469-7580.2009.01202.x
复制
发表时间：
2010-04-01
影响因子：
2.4
通讯作者：
Hutchinson, John R.
中科院分区：
文献类型：
--
作者：
Allen, Vivian;Elsey, Ruth M.;Hutchinson, John R.
鳄鱼展示了令人着迷的多样性的陆地步态和肢体运动，但仍然缺乏描述，对于了解它们的自然历史和进化非常重要。他们的肌肉骨骼解剖是这种多样性的关键，但目前只有对肌肉-肌腱单位解剖的定性研究。对个体发育系列标本(n=15，体质量0.5~60 kg)，记录了扬子鳄胸肢和盆肢肌肉的相对质量和内部构筑(束长度和生理横截面积)。通过减少长轴回归来分析数据，以确定与体重的比例关系。研究发现，骨盆肢体的伸肌(反重力)的生理横截面积和肌肉力量产生能力大于胸肢，这反映出鳄鱼与哺乳动物的不同之处在于，鳄鱼的后肢负荷大于前肢。肌肉质量和建筑通常被发现与身体质量成等距比例，这表明陆地运动能力的个体发育下降。这与之前的研究结果一致，这些研究表明，四肢骨骼长度的个体发育减少，以及力量下降的一般标度原理：动物的体重比率随着体型的增加而增加。等长测量发现的例外包括双侧肢体伸肌肌束长度的正异速生长，这表明工作范围的个体发育增加被解释为姿势可变性的增加--特别是主要的髋伸肌群--其解释因先前描述的这些肌肉的力矩臂的个体发育增加而复杂化。
Crocodylians exhibit a fascinating diversity of terrestrial gaits and limb motions that remain poorly described and are of great importance to understanding their natural history and evolution. Their musculoskeletal anatomy is pivotal to this diversity and yet only qualitative studies of muscle-tendon unit anatomy exist. The relative masses and internal architecture (fascicle lengths and physiological cross-sectional areas) of muscles of the pectoral and pelvic limbs of American alligators (Alligator mississippiensis Daudin 1801) were recorded for an ontogenetic series of wild specimens (n = 15, body masses from 0.5 to 60 kg). The data were analysed by reduced major axis regression to determine scaling relationships with body mass. Physiological cross-sectional areas and therefore muscle force-generating capacity were found to be greater in the extensor (anti-gravity) muscles of the pelvic limb than in the pectoral limb, reflecting how crocodylians differ from mammals in having greater loading of the hindlimbs than the forelimbs. Muscle masses and architecture were generally found to scale isometrically with body mass, suggesting an ontogenetic decrease in terrestrial athleticism. This concurs with the findings of previous studies showing ontogenetic decreases in limb bone length and the general scaling principle of a decline of strength : weight ratios with increasing size in animals. Exceptions to isometric scaling found included positive allometry in fascicle length for extensor musculature of both limbs, suggesting an ontogenetic increase in working range interpreted as increasing postural variability - in particular the major hip extensors - the interpretation of which is complicated by previous described ontogenetic increase of moment arms for these muscles.