Department of Organismal Biology and Anatomy, The University of Chicago, 1027 E 57th St, Chicago, IL 60637, USA
Department of Ecology and Evolutionary Biology, Brown University, 80 Waterman Street, Providence, RI 02912, USA.
J Exp Biol. 2019 Jul 10;222(Pt 13):jeb197681. doi: 10.1242/jeb.197681.
Many species of fish process their prey with cyclic jaw motions that grossly resemble those seen in mammalian mastication, despite starkly different tooth and jaw morphologies. The degree of similarity between the processing behaviors of these disparate taxa has implications for our understanding of convergence in vertebrate feeding systems. Here, we used XROMM (X-ray reconstruction of moving morphology) to investigate prey processing behavior of , the ocellate river stingray, which has recently been found to employ asymmetrical, shearing jaw motions to break down its prey. We found that modulates its feeding kinematics to produce two distinct types of chew cycles: compressive cycles and overbite cycles. The latter are characterized by over-rotation of the upper jaw relative to the lower jaw, past the expected occlusal limit, and higher levels of bilateral asymmetry as compared with compressive chews. We did not find evidence of the mediolateral shearing motions typical of mammalian mastication, but overbite cycles appear to shear the prey item between the upper and lower toothplates in a propalinal fashion. Additionally, comparison of hyomandibular and jaw motions demonstrates that the angular cartilages decouple jaw displacement from hyomandibular displacement in rostrocaudal and mediolateral directions. The multiple similarities between mammalian mastication and the dynamic processing behavior of support the use of sub-family Potamotrygoninae as a model for studying evolutionary convergence of mastication-like processing.
许多鱼类在处理猎物时会进行周期性的颌部运动，这些运动与哺乳动物的咀嚼运动非常相似，尽管它们的牙齿和颌骨形态明显不同。这些不同类群的处理行为之间的相似程度对我们理解脊椎动物进食系统的趋同进化有影响。在这里，我们使用 XROMM（运动形态的 X 射线重建）来研究 ，即斑点河魟的猎物处理行为，最近发现它采用不对称的剪切颌运动来分解猎物。我们发现 调节其摄食运动学，产生两种不同类型的咀嚼循环：压缩循环和过咬循环。后者的特征是上颌相对于下颌过度旋转，超过预期的咬合极限，并且双侧不对称性比压缩咀嚼更高。我们没有发现典型的哺乳动物咀嚼的侧向剪切运动的证据，但过咬循环似乎以上下齿板之间的前向方式将猎物切成碎片。此外，对舌颌骨和颌骨运动的比较表明，角软骨在头尾部和侧向方向上使颌骨位移与舌颌骨位移解耦。哺乳动物咀嚼和 动态处理行为之间的多种相似性支持将 Potamotrygoninae 亚科作为研究咀嚼样处理趋同进化的模型。
