Bertozzo Filippo, Manucci Fabio, Dempsey Matthew, Tanke Darren H, Evans David C, Ruffell Alastair, Murphy Eileen
School of Natural and Built Environment, Queen's University Belfast, Belfast, UK.
CI2Paleo, Sociedade de Historia Natural, Torres Vedras, Portugal.
J Anat. 2020 Dec 1;238(5):1055-69. doi: 10.1111/joa.13363.
Paleopathology, or the study of ancient injuries and diseases, can enable the ecology and life history of extinct taxa to be deciphered. Large-bodied ornithopods are the dinosaurs with the highest frequencies of paleopathology reported to-date. Among these, the crested hadrosaurid Parasaurolophus walkeri is one of the most famous, largely due to its dramatic elongated and tubular nasal crest. The holotype of Parasaurolophus walkeri at the Royal Ontario Museum, Canada, displays several paleopathologies that have not been discussed in detail previously: a dental lesion in the left maxilla, perhaps related to periodontal disease; callus formation associated with fractures in three dorsal ribs; a discoidal overgrowth above dorsal neural spines six and seven; a cranially oriented spine in dorsal seven, that merges distally with spine six; a V-shaped gap between dorsal spines seven and eight; and a ventral projection of the pubic process of the ilium which covers, and is fused with, the lateral side of the iliac process of the pubis. These lesions suggest that the animal suffered from one or more traumatic events, with the main one causing a suite of injuries to the anterior aspect of the thorax. The presence of several lesions in a single individual is a rare observation and, in comparison with a substantial database of hadrosaur paleopathological lesions, has the potential to reveal new information about the biology and behavior of these ornithopods. The precise etiology of the iliac abnormality is still unclear, although it is thought to have been an indirect consequence of the anterior trauma. The discoidal overgrowth above the two neural spines also seems to be secondary to the severe trauma inflicted on the ribs and dorsal spines, and probably represents post-traumatic ossification of the base of the nuchal ligament. The existence of this structure has previously been considered in hadrosaurs and dinosaurs more generally through comparison of origin and insertion sites in modern diapsids (Rhea americana, Alligator mississippiensis, Iguana iguana), but its presence, structure, and origin-attachment sites are still debated. The V-shaped gap is hypothesized as representing the point between the stresses of the nuchal ligament, pulling the anterior neural spines forward, and the ossified tendons pulling the posterior neural spines backward. Different reconstructions of the morphology of the structure based on the pathological conditions affecting the neural spines of ROM 768 are proposed. Finally, we review the history of reconstructions for Parasaurolophus walkeri showing how erroneous misconceptions have been perpetuated over time or have led to the development of new hypotheses, including the wide neck model supported in the current research.
古病理学，即对古代损伤和疾病的研究，能够帮助解读已灭绝分类单元的生态和生活史。大型鸟脚亚目恐龙是迄今为止报道中古病理学出现频率最高的恐龙。其中，有冠饰的鸭嘴龙科沃克氏副栉龙是最著名的恐龙之一，主要因其显著延长的管状鼻冠。加拿大皇家安大略博物馆收藏的沃克氏副栉龙的正模标本显示出一些此前未被详细讨论过的古病理学特征：左上颌骨的一处牙齿病变，可能与牙周病有关；三根背肋骨折处伴有骨痂形成；第六和第七节背神经棘上方有盘状增生；第七节背椎有一个向前的棘突，在远端与第六节棘突融合；第七和第八节背棘之间有一个V形间隙；以及髂骨耻骨突的腹侧突起，覆盖并与耻骨髂突的外侧融合。这些损伤表明这只动物遭受了一次或多次创伤事件，主要的那次创伤对胸部前方造成了一系列损伤。在单个个体中出现多种损伤的情况较为罕见，与大量鸭嘴龙古病理学损伤数据库相比，有可能揭示有关这些鸟脚亚目恐龙生物学和行为的新信息。髂骨异常的确切病因仍不清楚，尽管人们认为它是前部创伤的间接后果。两个神经棘上方的盘状增生似乎也是肋骨和背棘严重创伤的继发结果，并可能代表项韧带基部的创伤后骨化。此前人们通过比较现代双孔类动物（美洲鸵鸟、密西西比鳄、绿鬣蜥）的起源和附着部位，对鸭嘴龙及更广泛的恐龙中的这种结构的存在进行过研究，但它的存在、结构以及起源附着部位仍存在争议。V形间隙被推测代表项韧带向前拉前神经棘的应力与骨化肌腱向后拉后神经棘的应力之间的平衡点。基于影响皇家安大略博物馆768号标本神经棘的病理状况，提出了该结构形态的不同重建方案。最后，我们回顾了沃克氏副栉龙的重建历史，展示了错误的误解是如何随着时间的推移而延续，或者如何导致新假说的发展，包括当前研究中支持的宽颈模型。
