A shrewd inspection of vertebral regionalization in large shrews (Soricidae: Crocidurinae)
Smith, Stephanie M; Angielczyk, Kenneth D (2022), A shrewd inspection of vertebral regionalization in large shrews (Soricidae: Crocidurinae), Dryad, Dataset, https://doi.org/10.5061/dryad.1g1jwstxc
The regionalization of the mammalian spinal column is an important evolutionary, developmental, and functional hallmark of the clade. Vertebral column regions are usually defined using transitions in external bone morphology, such as the presence of transverse foraminae or rib facets, or measurements of vertebral shape. Yet the internal structure of vertebrae, specifically the trabecular (spongy) bone, plays an important role in vertebral function, and is subject to the same variety of selective, functional, and developmental influences as external bone morphology. Here we investigated regionalization of external and trabecular bone morphology in the vertebral column of a group of shrews (family Soricidae). The primary goals of this study were to: 1) determine if vertebral trabecular bone morphology is regionalized in large shrews, and if so, in what configuration relative to external morphology; 2) assess correlations between trabecular bone regionalization and functional or developmental influences; and 3) determine if external and trabecular bone regionalization patterns provide clues about the function of the highly modified spinal column of the hero shrew Scutisorex. Trabecular bone is regionalized along the soricid vertebral column, but the configuration of trabecular bone regions does not match that of the external vertebral morphology, and is less consistent across individuals and species. The cervical region has the most distinct and consistent trabecular bone morphology, with dense trabeculae indicative of the ability to withstand forces in a variety of directions. Scutisorex exhibits an additional external morphology region compared to unmodified shrews, but this region does not correspond to a change in trabecular architecture. Although trabecular bone architecture is regionalized along the soricid vertebral column, and this regionalization is potentially related to bone functional adaptation, there are likely aspects of vertebral functional regionalization that are not detectable using trabecular bone morphology. For example, the external morphology of the Scutisorex lumbar spine shows signs of an extra functional region that is not apparent in trabecular bone analyses. It is possible that body size and locomotor mode affect the degree to which function is manifest in trabecular bone, and broader study across mammalian size and ecology is warranted to understand the relationship between trabecular bone morphology and other measures of vertebral function such as intervertebral range of motion.
Scans of soricid vertebral columns (museum specimens sourced from the Field Museum of Natural History) were collected using a GE phoenix v|tome|x µCT scanner. Linear measurements were taken on 3D models of vertebrae using Meshmixer and 3DSlicer. Spherical VOIs were chosen and segmented in ORS Dragonfly 2020.1. Deep learning classifiers were trained using ORS Dragonfly's Deep Learning Toolkit. TBA data were collected from spherical VOIs using Quant3D. See publication Methods section for additional details.
Each data type (Deep Learning classifiers, spherical VOIs, linear and trabecular bone measurements) has a relevant ReadMe file with all relevant and necessary details.
National Science Foundation, Award: DBI-1811627