Hindlimb and pelvic anatomy of Caiman yacare (Archosauria, Pseudosuchia): myology and osteological correlates with emphasis on lower leg and autopodial musculature

MARIA EUGENIA PEREYRA; MAURICIO CERRONI; AGUSTINA LECUONA; PAULA BONA; LUCILA FERNÁNDEZ; ALEJANDRO OTERO

JOURNAL OF ANATOMY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2023

0021-8782

The anatomy of the archosaurian pelvic and hindlimb has adopted diverse successful configurations allowing a wide range of postures during the evolution of the group (e.g., erect, sprawl). For this reason, thorough studies of the structure and function of the pelvic and hindlimb, musculature of crocodylians are required and provides the possibility to expand their implications for the evolution of archosaurian locomotion, as well as to identify potential new characters based on muscles and their bony correlates. In this work, we gave a detailed description of the pelvic and hindlimb musculature of the South American alligator Caiman yacare, providing comprehensive novel information regarding lower limb and autopodial muscles. Particularly for the pedal muscles, we proposed a new classification for the dorsal and ventral autopodium muscles based on the organization of these muscles in successive layers. We study myology in a global background in which we compared the Caiman yacare musculature with other crocodylian. In this sense, differences in the arrangement of m. flexor tibialis internus 1, m. flexor tibialis externus, m. iliofibularis, mm. puboischiofemorales interni 1 and 2 between C. yacare and other crocodylians were found. We also discussed the muscle attachment that had distinct bony correlates and their morphological variation between crocodylian species. Most of the correlates did not exhibit great variation between the species compared, being the most prominent correlates related to the pelvic girdle; however, some bony correlates associated with the pedal muscles were highlighted here for the first time. This research provided a wide framework for future studies on comparative anatomy, and functional morphology, which could contribute to improve the character definition used in phylogenetic analyses, and to understand the patterns of musculoskeletal hindlimb evolution.