Dissertation Research: Functional Morphology, Ontogeny, and Evolution of New Hard Tissue, Trabecular Cartilage

布雷纳德9801636 尽管有一个完全软骨骨架，鲨鱼和鳐可以夸耀最快的鱼，灰鲭鲨;最大的鱼，鲸鲨;和一种可以压碎蛤蜊和螃蟹的鱼，牛鼻鳐。鲨鱼和鳐鱼骨骼中的一种特殊的软骨叫做棱柱软骨，它由一个柔软的核心组成，周围环绕着一层钙晶体，这些钙晶体可以覆盖骨骼元素。尽管表面矿化，棱柱形软骨不如骨骼坚硬和坚固，这应该排除了使用下颚压碎坚硬猎物的可能性。初步研究结果表明，牛鼻鳐，Rhinoptera bondarium，加强其颌骨与一个新的描述类型的棱柱软骨，“小梁软骨”。在小梁软骨中，硬矿物质的支柱以防止颌表面变形的模式穿过软骨核心。本研究将探讨小梁软骨的几个关键方面。小梁的生物力学功能将使用借用材料工程的技术来确定。将检查支柱的发育，以确定矿物质如何沉积在不含血管的软骨深处。最后，这个拟议的适应粉碎硬猎物的进化历史将被确定。

Brainerd 9801636 In spite of having an entirely cartilaginous skeleton, the sharks and rays can boast of the fastest fish, the Mako Shark; the largest fish, the Whale Shark; and a fish which can crush clams and crabs, the Cownose Ray. particular type of cartilage in the skeleton of sharks and rays is called prismatic cartilage, and it is composed of a soft core surrounded by plates of calcium crystals that serve to stiffen the skeletal elements. Despite this surface mineralization, prismatic cartilage is less stiff and strong than bone, and this should preclude the use of the jaws to crush hard prey. Preliminary results for this proposal indicate that the Cownose Ray, Rhinoptera bonasus, stiffens its jaws with a newly described type of prismatic cartilage, "trabecular cartilage". In trabecular cartilage, struts of hard mineral run through the cartilage core in a pattern that prevents deformation of the surface of the jaws. This study will investigate several key aspects of trabecular cartilage. The biomechanical function of trabeculae will be determined using techniques borrowed from materials engineering. The development of the struts will be examined to determine how mineral is deposited deep within a cartilage that contains no blood vessels. Finally, the evolutionary history of this proposed adaptation for crushing hard prey will be determined.