Two great papers by Sophie Regnault and Phil Fahn-Lai on reptile/mammal shoulder muscle anatomy! This work was supported by NSF Bio.
First, Sophie presents her work detailing the shoulder musculoskeletal anatomy of the short-beaked echidna. Turns out, our little monotreme friend has very conservative muscle architectural properties, compared to both reptiles and therian mammals.
Regnault S, Fahn-Lai P, Norris R, Pierce SE. 2020. Shoulder muscle architecture in the echidna (Monotremata: Tachyglossus aculeatus) indicates conserved functional properties. Journal of Mammalian Evolution. doi.org/10.1007/s10914-020-09498-6.
Second, Phil conducts a thorough topological and architectural analysis of the shoulder musclulature in the tegu lizard and Virginia opossum. Cool results: there are few statistical differences in architecture properties between these two species and those that are different can be correlated with changes in limb posture and shoulder girdle simplification in mammals.
Fahn-Lai P, Biewener AA, Pierce SE. 2020. Broad similarities in shoulder muscle architecture and organization across two amniotes: implications for reconstructing non-mammalian synapsids. PeerJ. p.e8556.
