Musculoskeletal modeling of sprawling and parasagittal forelimbs provides insight into synapsid postural transition

iScience

Stephanie E. Pierce¹  Philip Fahn-Lai²  Robert J. Brocklehurst³  Sophie Regnault³ 

[1] Concord Field Station and Department of Organismic and Evolutionary Biology, Harvard University, Bedford, MA01730, USA;Corresponding author;Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 01239, USA;

关键词: Comparative anatomy;    Zoology;    Evolutionary biology;    Biomechanics;   

DOI  :  

来源: DOAJ

【 摘 要 】

Summary: The sprawling–parasagittal postural shift was a major transition during synapsid evolution, underpinned by reorganization of the forelimb, and considered key to mammalian ecological diversity. Determining when and how this transition occurred in the fossil record is challenging owing to limited comparative data on extant species. Here, we built forelimb musculoskeletal models of three extant taxa that bracket sprawling–parasagittal postures—tegu lizard, echidna, and opossum—and tested the relationship between three-dimensional joint mobility, muscle action, and posture. Results demonstrate clear functional variation between postural grades, with the parasagittal opossum occupying a distinct region of pose space characterized by a highly retracted and depressed shoulder joint that emphasizes versatility and humeral elevation. Applying our data to the fossil record support trends of an increasingly retracted humerus and greater elevation muscle moment arms indicative of more parasagittal postures throughout synapsid evolution.

【 授权许可】

Unknown