The Functional and Phylogenetic Implications of the Myology of the Lumbar Region, Tail, and Hind Limbs of the Lesser Grison (Galictis cuja)

Abstract

Mustelids are a morphofunctionally diversified group. However, there are no descriptions of the postcranial musculature of South American mustelid species except for some comments from the 19th century. Here, we present the first description of the myology of the hind limbs, and lumbar, sacral, and caudal regions of the lesser grison (Galictis cuja), a short-legged South American mustelid, including muscle maps and weight data. We interpret the function and the evolution of several muscular features within a comparative framework and through the optimization of these traits onto a phylogeny. The configuration of the axial musculature (e.g., m. quadratus lumborum with short bundles, heavy iliocostalis, and forward originated sacrocaudalis dorsalis) and the presence of strong ankle musculature are features shared with mustelines and, to a lesser degree, with other musteloids. These could be related to a high mobility of the axial skeleton and strong control of the movement of the ankle joint, in relation to the acquisition of epigean bounding gaits, a crouched locomotion, and enhanced maneuverability inside burrows. We recorded many phylogenetically significant traits, shared with other arctoids (e.g., subdivision of m. gluteus profundus and semimembranosus, presence of a single belly for m. sartorius, and absence of articularis coxae) or exclusively musteloids (e.g., frequent fusion between m. piriformis and gluteus medius). Some features (e.g., restricted origin of the caudal belly of the m. semitendinosus, absence of gluteofemoralis, and unusually complex fibularis brevis) seem to be derived conditions acquired in some mustelid clades. Our results sustain the value of myological data for functional and phylogenetic studies.

Integrating locomotion, postures and morphology: The case of the tayra, Eira barbara (Carnivora, Mustelidae)

“…m. iliocostalis lumborum) and hip (i.e. hamstrings), which act on the sagittal plane for an effective propulsive phase of each bound (Gambaryan, 1974;Roberts, 1974;Williams, 1983;Álvarez et al, 2013;Ercoli et al, 2013Ercoli et al, , 2015. Moreover, the posterior (in terrestrial half-bounders) or posteromedial (in climbing half-bounders) orientation of the lesser trochanter, where flexor muscles of the lumbar region and hip are inserted (i.e.…”

Geographic variation in the skull morphology of the lesser grison (Galictis cuja: Carnivora, Mustelidae) from two Brazilian ecoregions

“…The majority available literature on this species includes information about its trophic ecology in Argentina, Chile, Uruguay, and southern Brazil ( Ebensperger, Mella & Simonetti, 1991 ; Diuk-Wasser & Cassini, 1998 ; Delibes et al, 2003 ; Kraus & Rödel, 2004 ; Zapata et al, 2005 ; Sade, Rau & Orellana, 2012 ; Kasper et al, 2015 ), habitat selection ( Zúñiga, Muñoz-Pedreros & Fierro, 2009 ), and anatomy ( Ercoli et al, 2012 , 2016 ). Except for the studies of Zapata et al (2008) and Schiaffini & Prevosti (2013) and a revision of the morphological and molecular characteristics of the genus Galictis ( Bornholdt et al, 2013 ), the cranial morphology of the species has been largely unexplored, even in ecomorphological studies of Mustelidae ( Catalano, Ercoli & Prevosti, 2014 ; Law et al, 2018 ).…”

Digging the compromise: investigating the link between limb bone histology and fossoriality in the aardvark (Orycteropus afer)

“…Such adaptations have been described in a comparative framework since the early 20th century ( Shimer, 1903 ). Osteological and muscular characters linked with fossoriality in extant mammals have been the focus of many morphoanatomical studies in the last few decades, for example, on monotremes ( Gambaryan et al, 2015 ), marsupials ( Warburton et al, 2013 ), xenarthrans ( Vizcaíno, Fariña & Mazzetta, 1999 ; Vizcaíno & Milne, 2002 ; Olson et al, 2016 ), rodents ( Gasc et al, 1985 ; Thorington, Darrow & Betts, 1997 ; Elissamburu & Vizcaíno, 2004 ; Lagaria & Youlatos, 2006 ; Samuels & Van Valkenburgh, 2008 ; Elissamburu & De Santis, 2011 ), true moles ( Rose et al, 2013 ), golden moles ( Gasc et al, 1986 ), and mustelids ( Ercoli et al, 2013 , 2015 ; Moore et al, 2013 ; Rose et al, 2014 ). Many of these studies have focused on the forelimb of scratch-diggers, that is, animals that dig by alternately flexing and extending their limbs to cut and loosen the soil with their claws ( Hildebrand, 1974 ), and have identified several anatomical markers linked with fossoriality in the limb bones of scratch-digging mammals (e.g., enlarged medial epicondyle in the humerus, elongated olecranon process in the ulna), which have been used to define quantitative measurements to assess degrees of fossoriality among these groups (see reviews in Hildebrand, 1985 ; Reichman & Smith, 1990 ).…”