Ontogenetic bite-force modeling of Alligator mississippiensis: implications for dietary transitions in a large-bodied vertebrate and the evolution of crocodylian feeding
Ontogenetic bite-force modeling of Alligator mississippiensis: implications for dietary transitions in a large-bodied vertebrate and the evolution of crocodylian feeding
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DOI：
10.1111/jzo.12349
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发表时间：
2016-08-01
影响因子：
2
通讯作者：
Erickson, G. M.
中科院分区：
文献类型：
--
作者：
Gignac, P. M.;Erickson, G. M.
鳄类在个体发育过程中体型会大幅增加。特别是美国短吻鳄，密西西比短吻鳄，在孵化和衰老之间几乎跨越了四个体重等级。伴随着这些变化的是在rostrodental形态和喂养能力，促进饮食的重大转变的修改。这种解剖学变化与不同尺寸的生态位占据之间的关系尚不清楚。在这项研究中，我们专注于个体发育变化的影响力产生机制的颌骨关闭，以评估缩放对摄食生物力学的影响。我们开发了基于解剖的肌肉骨骼模型，在整个个体发育过程中产生最大咬合力，并与A.mississippiensis发育系列的数据进行了比较和测试，其中咬合力直接测量。通过对模型参数范围内尺度模式的检验，我们讨论了美洲鳄颌内收肌系统中的肌肉羽状排列和正异速生长是如何促进捕食策略和对猎物的口腔加工的，以及对这一大型类群的发育生态位转移的贡献。我们认为，我们的研究结果是广泛适用于皇冠鳄鱼，并反映了一个重要的，但往往被忽视，鳄鱼喂养生态形态学方面：沿岸的，坐着等待捕食增强腹后移位，特别是大，有力的腹翼肌。未来的研究鳄鱼的个体发育和进化的进食不应该忽视这些肌肉的功能和生态意义的饮食。
Crocodylians undergo substantial increases in size during ontogeny. The American alligator, Alligator mississippiensis, in particular traverses nearly four orders of body mass between hatching and senescence. Accompanying such changes are modifications in rostrodental morphology and feeding capabilities that facilitate major shifts in diet. How such anatomical changes relate to ecological niche occupation across sizes is not well understood. In this study, we focused on the effects of ontogenetic changes on the force-generating mechanisms for jaw closure to assess the impacts of scaling on feeding biomechanics. We developed dissection-based, musculoskeletal models of maximum bite-force generation throughout ontogeny and compared and tested their veracity with data from an A.mississippiensis developmental series, for which bite forces were directly measured. Through examinations of the scaling patterns within the parameters of our models, we discuss how muscle pennation and positive allometry in the American alligator jaw adductor system facilitate capture strategies and oral processing of prey, and contribute to developmental niche shifts in this large-bodied taxon. On the basis of conservation of the crocodylian jaw adductor system, we argue that our findings are broadly applicable to crown Crocodylia and reflect an important, but often overlooked, aspect of the crocodylian feeding ecomorphology: littoral, sit-and-wait predation is enhanced by posteroventrally displaced, exceptionally large, and forceful ventral pterygoideus muscles, in particular. Future studies on the ontogeny and evolution of feeding in crocodylians should not neglect the functional and ecological implications of these muscles' contributions to diet.