Comparative bone histology of the turtle shell (carapace and plastron): Implications for turtle systematics, functional morphology, and turtle origins

我们最近在化石和最近的海龟的骨壳元素中发现了意想不到的组织学多样性和结构复杂性。在这个项目中，我们建议从系统问题的适用性、龟壳的生物力学以及测试海龟起源假说的潜力等方面来探索这一现象，这是一个目前备受争议的话题。为此，我们建议对所有高等龟类进行组织学取样和研究，从已知最古老的龟——晚三叠世原龟开始，延伸到高度衍生的海洋皮龟科（棱皮龟）和三甲壳龟（软壳龟，我们在其中发现了高度组织的胶合板结构）。由于龟壳残骸是最常见的脊椎动物化石之一，因此取样相对容易，更令人惊讶的是，它们的组织学迄今尚未得到研究。

We recently discovered an unexpected histological diversity and structural complexity in the bony shell elements of fossil and recent turtles. In this project, we propose to explore this phenomenon in terms of its applicability to systematic questions, biomechanics of the turtle shell, and potential for testing hypothese of turtle origins, a topic that is hotly debated at present. To this end, we propose the histologic sampling and study of all higher turtle groups, beginning with the oldest known turtle, the Late Triassic Proganochelys, and extending to such highly derived as the marine Dermochelyidae (leatherback turtles) and Trionychidae (soft-shelled turtles, in which we discovered a highly organized plywood structure). Sampling is made relatively easy by remains of turtle shells beeing among the most common vertebrate fossils, making it even more surprising that their histology remains unstudied so far.