3D quantitative comparative analysis of long bone diaphysis variations in microanatomy and cross‐sectional geometry

Abstract

Long bone inner structure and cross-sectional geometry display a strong functional signal, leading to convergences, and are widely analyzed in comparative anatomy at small and large taxonomic scales. Long bone microanatomical studies have essentially been conducted on transverse sections but also on a few longitudinal ones. Recent studies highlighted the interest in analyzing variations of the inner structure along the diaphysis using a qualitative as well as a quantitative approach. With the development of microtomography, it has become possible to study three-dimensional (3D) bone microanatomy and, in more detail, the form-function relationships of these features. This study focused on the selection of quantitative parameters to describe in detail the cross-sectional shape changes and distribution of the osseous tissue along the diaphysis. Two-dimensional (2D) virtual transverse sections were also performed in the two usual reference planes and results were compared with those obtained based on the whole diaphysis analysis. The sample consisted in 14 humeri and 14 femora of various mammalian taxa that are essentially terrestrial. Comparative quantitative analyses between different datasets made it possible to highlight the parameters that are strongly impacted by size and phylogeny and the redundant ones, and thus to estimate their relevance for use in form-function analyses. The analysis illustrated that results based on 2D transverse sections are similar for both sectional planes; thus if a strong bias exists when mixing sections from the two reference planes in the same analysis, it would not problematic to use either one plane or the other in comparative studies. However, this may no longer hold for taxa showing a much stronger variation in bone microstructure along the diaphysis. Finally, the analysis demonstrated the significant contribution of the parameters describing variations along the diaphysis, and thus the interest in performing 3D analyses; this should be even more fruitful for heterogeneous diaphyses. In addition, covariation analyses showed that there is a strong interest in removing the size effect to access the differences in the microstructure of the humerus and femur. This methodological study provides a reference for future quantitative analyses on long bone inner structure and should make it possible, through a detailed knowledge of each descriptive parameter, to better interpret results from the multivariate analyses associated with these studies. This will have direct implications for studies in vertebrate anatomy, but also in paleontology and anthropology.

Morphological diversification of biomechanical traits: mustelid locomotor specializations and the macroevolution of long bone cross-sectional morphology

“…These findings fit well with broader patterns throughout the vertebrate skeleton, indicating linkages of form, function and behavior or performance; in other words, that bone geometry grossly reflects loading patterns. For example, differences in long bone cross-sectional traits have been reported in birds of differing locomotor modes [34, 92] and primates differing in slow climbing, suspensory, and leaping locomotor habits [16, 44, 86]. While many prior studies have focused on external bone dimensions and their relationships with higher-level biological factors such as locomotion, we have contributed a new, focused analysis of Mustelidae using the valuable perspective that analysis of internal (i.e.…”

The evolution of femoral cross‐sectional properties in sciuromorph rodents: Influence of body mass and locomotor ecology

“…Generally, it is argued that terrestrial mammals increasing in body mass have to display relatively sturdier limb bones, reflected in positive allometry of bone robustness variables (e.g., Biewener, ; Garcia & Dasilva, ; Houssaye, Taverne, & Cornette, ; Samuels & van Valkenburgh, ). Positive allometry in CSP (or other measures for robustness) in femora has been observed before in various mammalian clades, such as scansorial mustelids (Heinrich & Biknevicius, ), prosimian primates (Demes & Jungers, ), felids (Doube et al, ), artiodactyls and diprotodonts (Doube et al, ).…”

What about limb long bone nutrient canal(s)? – a 3D investigation in mammals

“…The material includes humeri and femora from two datasets (see Table ) already available from previous studies (Houssaye et al ; Houssaye & Botton‐Divet, ), and representing adult specimens. The first one (hereafter referred to as QM) consists of 15 quadrupedal mammal species of various sizes, morphologies, locomotor modes, and that are widespread on mammal phylogeny (see Table ).…”