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

我们最近在化石和新发现的海龟的骨壳元素中发现了意想不到的组织多样性和结构复杂性。在这个项目中，我们打算从它对系统问题的适用性、龟壳的生物力学以及检验龟类起源假说的可能性等方面来探索这一现象，这是目前激烈辩论的一个话题。为此，我们建议对所有高等龟类进行组织学采样和研究，从已知的最古老的海龟，晚三叠世的Proganochelys开始，扩展到高度衍生的海龟，如海龟(棱皮龟)和甲龟科(甲鱼，我们在其中发现了一种高度组织的胶合板结构)。在最常见的脊椎动物化石中，甲壳的残骸使得采样变得相对容易，这让人更惊讶的是，到目前为止，它们的组织学仍然没有得到研究。

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.