Comparative myology of the ankle of Leopardus wiedii and L. geoffroyi (Carnivora: Felidae): functional consistency with osteology, locomotor habits and hunting in captivity

Abstract

Leopardus wiedii (margay) is the only arboreal Neotropical felid able to climb head-first down trees, due to its ability to rotate its tarsal joint 180°. A closely related, similar-sized species, L. geoffroyi (Geoffroy´s cat) exhibits more typical terrestrial habits and lacks the arboreal capabilities of L. wiedii. There is osteological evidence that supports a mechanical specialization of L. wiedii´s tarsal joint for inversion, but there have been no studies on the myology of this specialization. Based on comparative gross-anatomy dissections of zeugo- and autopodial muscles related to the ankle joint of one margay specimen and two Geoffroy´s cats, we identified myological specializations of L. wiedii that support its arboreal abilities. In addition, we documented both species hunting the same prey (domestic pigeon Columba livia, Aves: Columbidae) in captivity, to complement. We report differences in the origin, insertion and belly in 8 of the 10 dissected muscles. At least 3 of these interspecific variations can be associated with strengthening of the main muscles that command inversion/eversion movements of the tarsal joint and support the body weight in the head-down climbing position typical of L. wiedii. Frame-by-frame video reconstructions depict the sequence of movements in these species while hunting and highlight the advantages of the arboreal abilities of L. wiedii.