Population level measures of skeletal pathologies in Mesozoic marine reptiles (Ichthyosauria)

古病理学是研究生物化石中的疾病和损伤的学科。它最引人注目的应用可以说是推断中生代脊椎动物的古生态学，行为和营养关系。在种群水平上，骨化硬组织的创伤性改变的频率可以揭示有关古代生态系统动态的重要信息，尽管创伤的最终原因往往难以确定。重要的是，缺乏足够的定量测试使得化石记录中骨骼病变的总体流行率不清楚，并导致缺乏明确的假设。我们目前的项目已经进行了第一次定量评估的古病理学在鱼龙，一组的古龙类secondarily海洋爬行动物著名的记录从早侏罗世PosidonienfenferFormation西南德国。我们编制了一个基线数据集的骨骼病理从五个鱼龙属在这个地层限制的时间间隔，以测试的变化率的病理发生和分布。我们观察到广泛的病理在Posidonia页岩鱼龙动物群，与头骨，肋骨，gastralia和前肢受伤特别普遍。在所有种属中均观察到病理性骨骼改变。我们测试了在生活中骨骼损伤与体型和个体发育状态（青少年与成年人）的关系。结果表明，病理是更频繁的成年人比少年，并在较大的物种比较小的物种相对更频繁。然而，这些初步的观察结果并不完全符合已发表的鱼龙骨骼病理学记录。例如，关节疾病的频率在Posidonia页岩鱼龙动物群中比其他地质单位低得多，肋骨创伤的发生率似乎要高得多。为了更严格地评估这些数据，并通过空间和时间的相关性，我们建议调查可比的鱼龙动物群，从中三叠世到早白垩世的骨病的频率。我们假设病理的相对频率在连续的时间箱中保持不变，并且可能更受身体大小和个体发育的内在影响。这个项目的扩展将建立一个新的范式，从保存的脊椎动物化石中的损伤和疾病痕迹推断古生物学。

Paleopathology is the study of illness and injury in fossil organisms. Its most spectacular application has arguably been to infer paleoecology, behaviour and trophic relationships in Mesozoic vertebrates. The frequency of traumatic modification in fossilized hard tissues at the population level can reveal important information about ancient ecosystem dynamics, although the ultimate cause of the trauma is often difficult to identify. Critically, a lack of adequate quantitative testing has rendered the overall prevalence of skeletal pathologies in the fossil record unclear, and has led to a dearth of explicit hypotheses. Our current project has undertaken the first quantitative assessment of paleopathologies in ichthyosaurs, a group of dolphin-like secondarily marine reptiles famously documented from the Early Jurassic Posidonienschiefer Formation of southwestern Germany. We compiled a baseline data set of skeletal pathologies from five ichthyosaurian genera over this stratigraphically restricted interval to test for variability in the rate of pathological occurrence and distribution. We observed a broad range of pathologies in the Posidonia Shale ichthyosaur fauna, with injuries to the skull, ribs, gastralia, and forelimb being particularly prevalent. Pathological skeletal modifications were observed in all species. We tested the relationship of skeletal damage during life with body size and ontogenetic status (juvenile vs. adult). Results show that pathologies are more frequent in adults than in juveniles, and are relatively more frequent in larger than in smaller species. However, these preliminary observations are not entirely consistent with the published record of ichthyosaur skeletal pathologies. For instance, the frequency of articular disease is much lower in the Posidonia Shale ichthyosaur fauna than in other geological units, and the incidence of traumatic injuries to the ribs appears to be much higher. In order to evaluate this data more rigorously, and correlate through both space and time, we propose to survey the frequency of osteopathologies in comparable ichthyosaur faunas, ranging from the Middle Triassic through to Early Cretaceous. We hypothesize that the relative frequency of pathologies will remain constant across successive time bins, and is likely more intrinsically influenced by body size and ontogeny. This project extension will establish a novel paradigm for inferring paleobiology from preserved traces of injury and disease in fossil vertebrates.