This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: While the scapula is the primary bone supporting the body in terrestrial quadrupedal mammals, an analysis of internal bone structure in underground moles (family Talpidae) showed a more important role for the clavicle. An analysis of the internal bone structure led by a researcher at the University of Tsukuba offers the first evidence that load-transmission pathways within the shoulder girdle—the bones connecting the forelimbs to the body—shifted in response to moles' unique posture, with their forelimbs held widely out to the sides of the body and elbows facing upward.
The paper is published in the Journal of Anatomy. In terrestrial animals, ground forces, such as those experienced when supporting body weight or digging, are transmitted from the forelimbs to the body through the shoulder girdle. In typical quadrupedal mammals, which walk with their forelimbs beneath their bodies, the scapula appears to play the primary role in transmitting those forces to the body.
In contrast, underground moles have adapted to a fossorial lifestyle, adopting a posture in which their forelimbs are held widely out from the sides of their bodies. This posture might transmit forces to the shoulder girdle differently than in typical mammals. In this study, the researcher examined the internal structures of moles' clavicles and scapulae and compared them with those of the Asian house shrew (Suncus murinus), a closely related species that walks with its forelimbs beneath its body.
The results showed that, while the clavicle and scapula were more developed in moles than in Asian house shrews, the clavicle exhibited stronger internal structural features that were not observed in the scapula. Conversely, the shrew's internal structure was more robust in the scapula and less so in the clavicle. These findings suggest that the evolution of moles' unique posture was accompanied by a reorganization of load-transmission pathways within the shoulder girdle.
This approach of comparing internal bone structure may help future research reconstruct how the morphology and functional roles of individual skeletal elements in the shoulder girdle have changed throughout vertebrate evolution. Daichi Nakai, Bone histological evidence for posture‐related load transmission in the talpid pectoral girdle, Journal of Anatomy (2026). DOI: 10.1111/joa.70222 BSc Life Sciences & Ecology.
Microbiology lab background with pharmaceutical news experience in oil, gas, and renewable industries. Full profile → Bachelor's in mathematical biology, Master's in creative writing. Well-traveled with unique perspectives on science and language.
Extract — continue reading at the source.
