Muscular anatomy of the forelimb of Leopardus geoffroyi: Functional and phylogenetic aspects in Feliformia, part I. Proximal forelimb.

Abstract

Anatomical knowledge is fundamental for all species. In particular, myology allows a deeper understanding of ecomorphology-especially for those species hard to observe in the wild-and may be an important source for phylogenetic information. In this study, we analyzed the myological variation of the musculature of the shoulder and arm of the forelimb in species of the suborder Feliformia and its relationship with the phylogenetic history and the locomotor behavior, habitat, and predatory habits of the species within this group, using Leopardus geoffroyi as a case study. We used gross-anatomy dissections of the shoulder and arm of three specimens of L. geoffroyi and contrasted these results to other previously described feliform species. Additionally, we optimized 15 myological characters to search for phylogenetic patterns. We present the first description and the first complete muscular maps of the forelimb shoulder and upper arm of L. geoffroyi. A small number of muscular characteristics allow L. geoffroyi to be distinguished from other feliforms, such as a possible partial division of m. biceps brachii, although they did not relate to any analyzed ecological habit. Some myological characteristics studied in this work contribute to the knowledge of the phylogenetic relationships and the morphological evolution of Feliformia. Felids are the only feliforms with a constantly present m. pectoantebrachialis (although it has been reported in some caniforms). Muscle rhomboideus capitis is present only in Felidae and Herpestidae, resembling various caniforms. Its presence could indicate a retention linked to their carnivoran ancestry. The Felidae and Hyaenidae represent two quite conservative morphotypes, as they present particular muscular configurations compared to other feliform families, but also, relatively little variation within each family. Functionally, some myological characters recorded in hyenids, L. lynx, P. uncia, A. jubatus (e.g., radio-ulnar insertion of m. biceps brachii), distinguish them from the rest of the species of the same suborder or family, and are convergent with other carnivorans with cursorial habits (e.g., canids). The functional and evolutionary analysis of the myology of the forelimb of L. geoffroyi and the different species of the suborder Feliformia allowed a better understanding of how muscle configurations reflect functional specialization to different ways of life. The muscle maps presented here, being the first available for a small Neotropical felid, can be considered a valuable source of information, useful for future studies of comparative anatomy in neontological and paleobiological contexts.