Osteohistological correlates of muscular attachment in terrestrial and freshwater Testudines

Abstract

Sharpey's fibers are considered the anatomical structures integrated to the muscles. Since these fibers leave marks at the microscopic level, their presence and distribution are used as evidence of muscle attachment in extinct and extant forms. In recent years, studies have been focusing on muscle–bone and tendon–bone interaction mostly on mammals. The main objective of this work is to contribute to the morphological and histological knowledge of muscle attachment in other amniotes, such as reptiles, and their variation related to different locomotor habits. In this way, a study was performed on terrestrial and aquatic turtles. The musculature related to the movement of the humerus, and pectoral girdle in Chelonoidis chilensis, Phrynops hilarii and Hydromedusa tectifera was analyzed. Dissections were performed mapping the origins and insertions of each muscle and undecalcified thin sections were performed in specific muscular attachment sites. We found some differences which were not previously reported, related to the insertion of the m. pectoralis, the m. coracobrachialis magnus and the origin of the m. tractor radii. The osteohistology revealed the presence of Sharpey's fibers in the cortex of all the bone elements analyzed. Patterns were established in relation to the orientation and density of Sharpey's fibers, which were used for the categorization of each muscle attachment site. The comparative micro‐anatomical study of these areas did not reveal any important differences between terrestrial and freshwater turtles in muscles involved with the rotation, abduction and adduction of the humerus. In this way, the preliminary results suggest an absence of correlation between the distribution and density of Sharpey's fibers between different habitat forms, at least in the bones and species analyzed.

Palaeobiology of the early sauropodomorph Mussaurus patagonicus inferred from its long bone histology

“…It is worth noting that, despite the important area of attachment for the femorotibialis muscles in the sauropsid femora (Petermann & Sander 2013; Pereyra et al . 2019), histological correlates for this muscle are only recorded in restricted portions of the cortex. Such a pattern is possibly the result of the varying tensile forces acting differently on different parts of a bone.…”

Osteohistology of the hyperelongate hemispinous processes of Amargasaurus cazaui (Dinosauria: Sauropoda): Implications for soft tissue reconstruction and functional significance

“…Although the sole occurrence of Sharpey's fibres cannot be considered as unequivocal evidence for a singular soft tissue present in relation to an osseous structure (e.g. Pereyra et al, 2019; Petermann & Sander, 2013), their particular distribution and orientation along the hemispinous process of Amargasaurus and the dicreosaurid indet. MOZ‐Pv 6126–1 suggest their association with a particular soft tissue.…”

“…de Buffrénil et al, 1986; Main et al, 2005) and relationships with soft tissues (e.g. Hieronymus et al, 2009; Lambertz et al, 2018; Pereyra et al, 2019; Woodruff et al, 2016). Strictly taking into account hyperelongated structures of the vertebrate neural arches, paleohistological studies have been conducted on Edaphosauridae and Sphenacodontidae (e.g.…”

Bone histology of Neogene angulate tortoises (Testudines: Testudinidae) from South Africa: palaeobiological and skeletochronological implications

“…[52]). Moreover, although histological studies on chelonian limb bones and/or shell bones have been used to determine skeletochronology and reconstruct growth rates of the testudines [48,49,[53][54][55][56][57][58][59][60][61][62], histological data from a single species, involving both modern and fossilized individuals is non-existent. Here, we fill this gap by investigating the bone histology of Chersina angulata from the Miocene to present, to assess whether their growth dynamics and life-history patterns changed over the past 5 million years.…”