School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Godoy Cruz 2290, 1425, Ciudad Autónoma de Buenos Aires, Argentina.
BMC Ecol Evol. 2024 Jan 31;24(1):6. doi: 10.1186/s12862-023-02187-x.
Studies on pathological fossil bones have allowed improving the knowledge of physiology and ecology, and consequently the life history of extinct organisms. Among extinct vertebrates, non-avian dinosaurs have drawn attention in terms of pathological evidence, since a wide array of fossilized lesions and diseases were noticed in these ancient organisms. Here, we evaluate the pathological conditions observed in individuals of different brachyrostran (Theropoda, Abelisauridae) taxa, including Aucasaurus garridoi, Elemgasem nubilus, and Quilmesaurus curriei. For this, we use multiple methodological approaches such as histology and computed tomography, in addition to the macroscopic evaluation. The holotype of Aucasaurus shows several pathognomonic traits of a failure of the vertebral segmentation during development, causing the presence of two fused caudal vertebrae. The occurrence of this condition in Aucasaurus is the first case to be documented so far in non-tetanuran theropods. Regarding the holotype of Elemgasem, the histology of two fused vertebrae shows an intervertebral space between the centra, thus the fusion is limited to the distal rim of the articular surfaces. This pathology is here considered as spondyloarthropathy, the first evidence for a non-tetanuran theropod. The microstructural arrangement of the right tibia of Quilmesaurus shows a marked variation in a portion of the outer cortex, probably due to the presence of the radial fibrolamellar bone tissue. Although similar bone tissue is present in other extinct vertebrates and the cause of its formation is still debated, it could be a response to some kind of pathology. Among non-avian theropods, traumatic injuries are better represented than other maladies (e.g., infection, congenital or metabolic diseases, etc.). These pathologies are recovered mainly among large-sized theropods such as Abelisauridae, Allosauridae, Carcharodontosauridae, and Tyrannosauridae, and distributed principally among axial elements. Statistical tests on the distribution of injuries in these theropod clades show a strong association between taxa-pathologies, body regions-pathologies, and taxa-body regions, suggesting different life styles and behaviours may underlie the frequency of different injuries among theropod taxa.
对病态化石骨骼的研究提高了我们对生理学和生态学的认识，从而进一步了解了已灭绝生物的生活史。在已灭绝的脊椎动物中，非鸟类恐龙因其存在大量的化石病变和疾病而备受关注。在这里，我们评估了不同短吻鳄形类（兽脚亚目，阿贝力龙科）分类群个体中观察到的病理状况，包括 Aucasaurus garridoi、Elemgasem nubilus 和 Quilmesaurus curriei。为此，我们使用了多种方法，如组织学和计算机断层扫描，以及宏观评估。Aucasaurus 的正型标本显示出在发育过程中椎骨分段失败的几个特征，导致两个融合的尾椎存在。这种情况在 Aucasaurus 中发生，是迄今为止在非坚尾龙类兽脚亚目中记录的首例。关于 Elemgasem 的正型标本，两块融合椎骨的组织学显示椎体之间存在椎间盘间隙，因此融合仅限于关节面的远端边缘。这种病理学被认为是脊椎关节病，这是首例非坚尾龙类兽脚亚目脊椎关节病的证据。Quilmesaurus 右胫骨的微观结构排列显示在一部分外皮质中存在明显的变化，可能是由于存在辐射状纤维层状骨组织。虽然类似的骨组织存在于其他已灭绝的脊椎动物中，其形成原因仍存在争议，但它可能是某种疾病的反应。在非鸟类兽脚亚目中，创伤性损伤比其他疾病（如感染、先天或代谢性疾病等）更为常见。这些病变主要在大型兽脚亚目如阿贝力龙科、鲨齿龙科、鲨齿龙科和暴龙科中恢复，主要分布在轴性元素中。对这些兽脚亚目分类群中损伤分布的统计检验显示，分类群-病变、身体区域-病变和分类群-身体区域之间存在很强的关联，这表明不同的生活方式和行为可能是导致兽脚亚目分类群中不同损伤频率的原因。
