Comparative osteology and functional morphology of the forelimb ofCyonasua(Mammalia, Procyonidae), the first South American carnivoran

Abstract

Extant procyonids only inhabit the Americas and are represented by six genera (Procyon, Nasua, Nasuella, Bassaricyon, Potos, and Bassariscus); all of them, except Bassariscus, are present in South America. The first records correspond to the early Miocene in North America (NA) and the late Miocene in South America (SA). Cyonasua was the first carnivoran to enter SA from NA, before the Great American Biotic Interchange, and went extinct in the early middle Pleistocene. This extinct procyonid is recorded in several localities of Argentina, and also in Venezuela. Paleobiological studies of procyonids are interesting from evolutionary and biogeographical viewpoints. In this study, the pectoral girdle and forelimb of 10 specimens of Cyonasua are described and compared with extant South American procyonids using a qualitative approach. Additionally, four functional morphology indexes were calculated for them and compared with an ecologically diverse sample of living carnivorans. Results indicate that Cyonasua most resembles Nasua nasua and Procyon cancrivorus, even though the extinct procyonid possessed peculiar features. Cyonasua had robust and relatively short forelimb bones, with strong stabilized joints, and movements associated with the sagittal plane, which suggest a tendency toward terrestrial habits, related to their ability to resist relatively high bending and shearing stresses. However, some features indicate a freedom in their range of movements, with moderate supination ability, compatible with climbing. When combined with previous analyses of dietary habits and estimated body mass, the morphology of Cyonasua would be well suited for digging and prey manipulation, allowing them to prey on small and relatively large‐sized vertebrates, as well as to avoid some of the predators that were dominant in the Cenozoic of South America.

Gross anatomy of the craniolateral antebrachial muscles in kinkajou (Potos flavus, Carnivora): Intra‐ and interspecific variants within the family Procyonidae

“…Therefore, the high functional development of the brachioradialis muscle in P. flavus is associated with its high prehensility (Böhmer et al., 2019). Even its humerus has a higher development of the lateral supracondylar crest than other procyonids (Tarquini et al., 2019), since it serves to the origin of the brachioradialis and two extensor carpi radialis muscles completely separated. While in other procyonids, both extensor carpi radialis muscles can be partly or completely fused; however, these act functionally in all procyonids as an extensor of the carpus and flexor of the elbow.…”

“…The knowledge of the anatomical variants is necessary to review the phylogenetic relationship between species (Perdomo‐Cárdenas et al., 2021) and contributes to muscular reconstruction in procyonid fossils (Tarquini et al., 2019). The craniolateral antebrachial muscles have been described in P. flavus (Beswick‐Perrin, 1871; Böhmer et al., 2020; Julitz, 1909; Windle & Parsons, 1897).…”

Proximal Humerus Morphology Indicates Divergent Patterns of Locomotion in Extinct Giant Kangaroos

“…These differences in humeral proximal morphology between terrestrial and arboreal forms have primarily been observed in primates (e.g., Szalay and Dagosto 1980;Rose 1989;Gebo and Sargis 1994;Ride et al 1997;Schmitt 2003;Arias-Martorell 2018), but also in other mammals such as tree shrews (Sargis 2002), tenrecs (Salton andSargis 2008), didelphid marsupials (Argot 2001;Szalay and Sargis 2001), viverrids (Taylor 1974), felids (Walmesly et al 2012), procyonids (Tarquini et al 2019), caviomorph rodents (Morgan and Álverez 2013), and xenarthrans (Toledo et al 2013). Although most authors reported a phylogenetic signal within these lineages, the overall pattern of similarities both within and between lineages, and in marsupials as well as placentals, evidences a strong functional association between morphology and locomotion that overrides any phylogenetic effects.…”

Evolutionary history or function? Which preponderates in the expression of the muscle mass of the thoracic limb in wild carnivorans?

“…The thoracic limbs of carnivorans act in different functions such as locomotion in various terrains, digging, mating, sustaining body mass, and predation. Understanding the morphology of the thoracic limbs increases the comprehension of the type and size of prey, preference for habitats, peculiar movements of species and even allows extrapolations to extinct species (Andersson, 2004; Ewer, 1973; Fabre, Goswami, Peigné, & Cornette, 2014; Meachen‐Samuels & van Valkenburgh, 2009; Meloro, Elton, Louys, Bishop, & Ditchfield, 2013; Salesa, Antón, Turner, & Morales, 2010; Tarquini, Morgan, Toledo, & Soibelzon, 2019; van Valkenburgh, 1987).…”