Skeletal Trauma With Implications for Intratail Mobility in Edmontosaurus Annectens From a Monodominant Bonebed, Lance Formation (Maastrichtian), Wyoming Usa

Abstract

This study presents evidence of pre-mortem traumatic injury and its sequalae on multiple Edmontosaurus annectens skeletal elements recovered from a largely monodominant Cretaceous (Maastrichtian) bonebed. The sample consists of 3013 specimens excavated and prepared from two quarries, of which 96 elements manifest one or more macroscopic bone abnormalities and 55 specimens display pathology attributable to physical trauma. Evidence of traumatic pathology is strongly associated (P < .05) with body region, occurring disproportionately in the caudal vertebrae. Pre-mortem fractures with subsequent bone remodeling and hypertrophic ossification of caudal neural spines are present principally in the middle and mid-distal regions of the tail, while fractures of the vertebral centra are present primarily in the distal tail region. Other skeletal regions, such as chevrons, phalanges of the manus and ribs display unambiguous evidence of healed trauma, but with less frequency than the tail. These findings, in combination with current understanding of hadrosaurian tail biomechanics, indicate that intervertebral flexibility within the middle and mid-distal region of the tail likely rendered these caudal vertebrae more susceptible to the deleterious effects of repeated mechanical stress and subsequent trauma, potentially accompanying running locomotion and other high-impact herd interactions. Healed fractures within the region are also suggestive of accumulated injuries due to a combination of tail usage in defense and possibly accidental bumping/trampling associated with gregarious behavior.

Osseous paleopathologies of Bonapartesaurus rionegrensis (Ornithopoda, Hadrosauridae) from Allen Formation (Upper Cretaceous) of Patagonia Argentina

“…The occurrence of both pathological caudal vertebrae of Bonapartesaurus in the middle region of the tail is consistent with the interpretation of hadrosaurids having flexible and vulnerable middle to posterior region of the tail (Siviero et al, 2020). Hadrosaurids tail have moderate size epaxial muscles and large size hypaxial ones (Persons and Currie, 2014), where the major component of the latter is the caudofemoralis muscle, which tappers posteriorly reaching the middle of the tail (Siviero et al, 2020). The presence of this large muscle, combined with the presence of ossified tendons in the anterior half region of the tail, made the anterior region highly mechanically stable (Siviero et al, 2020).…”

“…It depends not only in having closely related living relatives on which be able to see the muscles, but also the osteological correlates on the studied fossil (Bryant and Russell, 1992;Witmer, 1995Witmer, , 1997. Many paleontologists have attempted to infer the muscles in fossil vertebrates, and particularly focused in mammals and dinosaurs (e.g., Tarsitano, 1981;Carrano and Hutchinson, 2002;Dilkes, 2000;Dumbravă et al, 2013;Norman, 1986;Schachner et al, 2011Schachner et al, , 2020Siviero et al, 2020).…”

“…In the hadrosaurid fossil record, the lesions in the tail elements are very common (Tanke and Rothschild, 2014;Siviero et al, 2020). Lesions in the tail are usually found in adults more than in juveniles, and they have been identified as fractures, spinal osteomyelitis, congenital deformities, spondyloarthropathies, and/or neoplasms (Ramirez-Velasco et al, 2017;Tanke and Rothschild, 2014).…”

Description and etiology of paleopathological lesions in the type specimen of Parasaurolophus walkeri (Dinosauria: Hadrosauridae), with proposed reconstructions of the nuchal ligament

“…Different reconstructions of the morphology of the structure based on the pathological conditions affecting the neural spines of ROM 768 are proposed. frequency of fossilized injuries and diseases among the dinosaurian fossil record (Bertozzo et al in prep;Rothschild et al, 2003;Siviero et al, 2020;Tanke & Rothschild, 2002. In addition, new research and technologies over the past 30 years have provided a larger sample of pathological specimens for comparative purposes, as well as enabling a better understanding to be gained of the external and internal structure of fossilized lesions and diseases in dinosaurs.…”

“…During Parks’ time, interest in dinosaur paleopathology was in its infancy (see Moodie, 1923), and no proper references or comparative material were available. Today, based on subsequent large collections of skeletons and skeletal material, we know that large ornithopod dinosaurs have the highest frequency of fossilized injuries and diseases among the dinosaurian fossil record (Bertozzo et al in prep; Rothschild et al, 2003; Siviero et al, 2020; Tanke & Rothschild, 2002, 2014). In addition, new research and technologies over the past 30 years have provided a larger sample of pathological specimens for comparative purposes, as well as enabling a better understanding to be gained of the external and internal structure of fossilized lesions and diseases in dinosaurs.…”