Durophagous vertebrates feed on shelled prey and share many morphological traits; in particular, high leverage jaws with robust jaw-closing muscles. Myliobatid stingrays are no exception, having reinforced jaw skeletons, large jaw adductor muscles, and with all species in the family consuming some combination of shelled prey. Myliobatid rays have a long evolutionary history (65–70 million years) and number over thirty species, yet despite similar performance demands given their diet ecology, exhibit considerable morphological diversity of the feeding apparatus. We examined how feeding performance changes in the bullnose ray, Myliobatis freminvillei over its ontogeny, and compared how these rays produce crushing bite forces relative to confamilial and co-occurring cownose rays (Rhinopterinae). Within the durophagous family Myliobatidae, rhinopterines are more generalist in their dietary preferences, feeding on small bivalves and infaunal crustaceans, whereas eagle rays (Aetobatinae) prey on gastropods and bivalves exclusively, while bullnose/bat rays (Myliobatinae) consume a size range of gastropods and hermit crabs. We found that bullnose rays show isometric changes in feeding performance over their ontogeny, relying on the high mechanical efficiency of their jaws to crush shelled prey throughout their ontogeny. This manner of generating high bite forces diverges from cownose rays and other durophagous elasmobranchs, which primarily rely on muscular hypertrophy to generate forceful bites. These two lineages evolved distinct means of dismantling hard prey, which further showcases how multiplicity of form can result in similar ecological function. These predators are frequently subsumed within a single ecological category, durophagy, which underestimates their diversity.

硬食性脊椎动物以带壳猎物为食，并具有许多共同的形态特征。特别是具有强健的下颌闭合肌肉的高杠杆下颌。黄貂鱼也不例外，它们具有强化的下颌骨骼和大下颌内收肌，并且该科中的所有物种都食用某种带壳猎物的组合。鳐鱼具有悠久的进化历史（65-7000万年），数量超过30种，然而，尽管它们的饮食生态具有相似的性能要求，但其摄食器官却表现出相当大的形态多样性。我们研究了牛鼻魟 ( Myliobatis freminvillei)的摄食性能如何变化对其个体发育进行了研究，并比较了这些魟鱼如何与同族和同时出现的牛鼻鳐（犀牛亚科）产生压碎的咬合力。在硬食性蝠鲼科中，犀鳍鳐类的饮食偏好更为普遍，以小型双壳类和动物甲壳类动物为食，而鹰鳐 (Aetobatinae) 则专门捕食腹足类和双壳类动物，而牛鼻/蝙蝠鳐 (Myliobatinae) 则捕食各种大小的腹足类动物和寄居蟹。我们发现，圆鼻鳐在其个体发育过程中的摄食性能表现出等距变化，在其个体发育过程中依靠其颌部的高机械效率来压碎带壳猎物。这种产生高咬合力的方式与牛鼻鳐和其他硬食性软骨鱼类不同，后者主要依靠肌肉肥大来产生强力咬合。这两个谱系进化出了不同的拆除坚硬猎物的方法，这进一步展示了形式的多样性如何导致相似的生态功能。这些捕食者经常被归入单一的生态类别，即食肉动物，这低估了它们的多样性。