Adaptations to cursoriality and digit reduction in the forelimb of the African wild dog (Lycaon pictus (original) (raw)
Related papers
Canadian Journal of Zoology, 2001
The relationship between manus proportions and forepaw dexterity in 33 species of carnivores (Carnivora) was examined. Both the analysis of "raw" data and independent contrasts revealed no significant correlation between the metacarpal-phalanx (MCP) ratio and forepaw dexterity. This result was corroborated by a common origins test, which indicated that changes in the MCP ratio were not coincident with changes in forepaw dexterity throughout carnivore evolution. Together, these results suggest that the morphological basis for variations in manipulative behaviour may be quite complex. Other morphological features, such as manus and carpal shape and myology, may play a critical role in forepaw dexterity, but are not manifested as changes in manus proportions. Behavioural observations also suggest that manus proportions may be correlated more closely with locomotion rather than non-locomotory forepaw usage.
A novel series of forepaw muscles for mammals observed in the Patagonian weaselLyncodon patagonicus
Journal of Mammalogy, 2016
The intrinsic autopodial musculature of mammals is composed of a relatively stable number of muscular groups. Here, we present the first myological studies of Lyncodon patagonicus, a South American mustelid that is morphologically and ecologically poorly known. The typical intrinsic muscles of the manus of Lyncodon are similar to those of its sister taxon Galictis, although there exist few variations, including additional subdivisions and relatively more distal insertions in some muscles. A striking feature is the presence of a novel series of forepaw muscles never before described for mammals. These muscles, named here mm. flexores digitorum proprii manus, are represented by a medial and a lateral belly for each digit and are located immediately distal to the mm. flexores breves profundi. They are located distally alongside the tendons of the latter, along the palmar aspect of the phalangeal series, and they insert onto the flexor tubercle of the distal phalanx of each digit. We propose that the incorporation of these muscles in the forepaw musculature of Lyncodon, in addition to some other osteo-myological features, imply a distinctive morpho-functional adaptation to increase the force of flexion and independence of digital movements likely used to grasp prey during hunting. This hypothesis should be confirmed by future ecological and behavioral studies on this species. La musculatura intrínseca del autopodio de los mamíferos está compuesta por un número de grupos musculares relativamente estable. En este trabajo nosotros presentamos el primer estudio miológico de Lyncodon patagonicus, un mustélido de América del Sur pobremente conocido tanto en aspectos morfológicos como ecológicos. Los músculos intrínsecos típicos de la mano de Lyncodon son similares a los presentes en el taxón hermano Galictis, aunque presenta algunas variaciones, incluyendo la presencia de subdivisiones adicionales y algunas inserciones relativamente más distales. Una característica distintiva fue la presencia de una novedosa serie de músculos nunca antes descripta para un mamífero. Estos músculos, aquí denominados mm. flexores digitorum proprii manus, están representados por un vientre medial y uno lateral para cada dígito, ubicados inmediatamente distales a los mm. flexores breves profundi. Distalmente, estos se ubican a los lados de los tendones de estos últimos, en el aspecto palmar de la serie falangeal, insertándose en los tubérculos flexores de las falanges distales de cada dígito. Nosotros proponemos que la incorporación de estos músculos a la musculatura de la mano de Lyncodon, sumado a otras características osteo-miológicas, podría implicar una adaptación morfo-funcional distintiva, posibilitando una mayor fuerza de flexión e independencia en los movimientos digitales, posiblemente utilizada por el taxón durante la manipulación de presas durante la caza. Esta función debe ser confirmada por futuros estudios ecológicos y comportamentales para esta especie.
The evolution of skilled forelimb movements in carnivorans
2000
Emancipating the forelimbs from locomotion for use in other activities, such as food manipulation, is a major evolutionary milestone. A variety of selective forces and evolutionary correlates may influence the evolution of various degrees of skill with which the forelimbs are used. Using the order Carnivora as a test group, I assessed the relative influence of six factors: relative brain size, neocortical volume, manus proportions, body size, phylogenetic relatedness, type of locomotion and diet I developed a rating system to describe the dexterity of individual species and compared the scores to the six factors using modem comparative methods. Only phylogeny and diet were significantly correlated with forelimb dexterity. More specifically, forelimb dexterity tends to be higher in caniform than in feliform carnivorans and decreases with increasing specialisation on vertebrate prey. I conclude that food handling and feeding niche breadth have a significant effect upon the evolution of skilled forelimb movements. iv ACKNOWLEDGEMENTS Firstly, I wish to thank Ian Whishaw and Sergio Pellis for offering me the opportunity to be their graduate student at such short notice and for their unwavering support throughout my thesis research. They both provided me the freedom, willingly or not, to 'do my own thing', but were always there when I needed some guidance. I would not have arrived here at all, however, without the inspiration of John Nelson who first introduced me to the behavioural analysis of reaching and grasping and provided me with the intellectual freedom to investigate behavioural phenomena on my own. This project could not have been completed without the assistance of the helpful staff at the following zoological institutions which I relied upon for my behavioural observations: Assiniboine Zoo (Winnipeg, MB), Calgary Zoo (Calgary, AB), Los Angeles County Zoo
Biological Journal of the Linnean Society
The arboreal environment is complex and irregular and imposes significant constraints on the locomotor ability of vertebrates, resulting in morphological adaptations. Carnivorans are of particular interest because they radiated several times independently into the arboreal milieu, leading to convergence in long bone anatomy. We investigated whether the forelimb muscles show differences in arboreal vs. terrestrial species and tested for convergence in muscle architecture. To do so, we studied the forelimb muscles in 17 species of carnivorans with different locomotor modes (arboreal and terrestrial). Our results showed that the forelimb musculature evolved in a convergent manner in arboreal species, resulting in more forceful and heavier wrist rotators and elbow flexors, even when accounting for phylogeny. This suggests that selective forces imposed by the environment drive the evolution of the muscular system towards a convergent phenotype that provides a functional advantage for locomotion in the complex threedimensional arboreal habitat.
Journal of Mammalian Evolution
A b s t r a c t T h e n i n e -b a n d e d a r m a d i l l o , D a s y p u s novemcinctus, is a member of the family Dasypodidae, which contains all extant species of armadillos and represents the most diverse group of xenarthran mammals by their speciation, form, and range of scratch-digging ability. This study aims to identify muscle traits that reflect specialization for fossorial habit by observing forelimb structure in D. novemcinctus and comparing it among armadillos using available myological data. A number of informative traits were observed in D. novemcinctus and among Dasypodidae, including the absence of m. rhomboideus profundus, the variable presence of a m. articularis humeri and m. coracobrachialis, two heads of m. triceps brachii with scapular origin, and a lack of muscle mass devoted to antebrachial supination. Muscle mass and myosin heavy chain (MHC) isoform content were also quantified from our forelimb dissections. New osteological indices are additionally calculated and reported for D. novemcinctus. Collectively, the findings emphasize muscle mass and power output for limb retraction and specialization of the distal limb for sustained purchase of soil by strong pronation and carpal/digital flexion. Moreover, the myological traits assessed here provide a valuable resource for interpretation of muscle architecture specializations among digging mammals and future reassessment of armadillo phylogeny.
Biological Journal of the Linnean Society, 2019
Prehension involves the ability to reach, grasp and transport an object. It is a fitness-relevant behaviour with an important role in food acquisition and locomotion. Grasping an item requires the coordinated action of several muscles and, consequently, the muscular anatomy can be expected to be a good indicator of grasping ability. Here, we quantitatively analyse the myology of the forelimb in Carnivora in relation to their grasping ability, arboreality and locomotor specializations. Carnivorans are a monophyletic group and a good model due to the fact that they vary in ecology and prehensile capabilities. We find that non-prehensile taxa differ in their muscle properties from poorly prehensile taxa and from intermediately to strongly prehensile taxa when taking into account variation in body size and phylogeny. Species with strong prehensile capabilities are characterized by a high force-producing capacity in the forelimb rotators. A strong grasp is not only advantageous for prehension, but also for climbing. Species with poor prehensile capabilities but an intermediate to high degree of arboreality display well-developed flexor muscles contributing to a strong grasp. Although anatomical adaptations for prehensility and arboreality are similar, the present study revealed differences in the muscle specializations of the forelimb in Carnivora.
Comparative Distal Limb Anatomy Reveals a Primitive Trait in 2 Breeds of Equus caballus
The 55-million-year history of equine phylogeny has been well documented from the skeletal record, however not the soft tissue structures that are now vestigial in modern horse. A recent study reported 2 ligamentous structures resembling functional 3rd and 4th interosseous muscles were evident in Dutch Konik horses. The current study investigates this finding and compares it to members of the genus Equus to identify either a breed anomaly or functional primitive trait. Distal limbs (n=571) were dissected from 4 species of Equus; E. caballus, E. asinus, E. przewalskii and E. burchelli beohmi. Breed representatives of E.caballus (n=18) included the primitive Dutch Konik. The 2nd and or 4th interosseous muscle was evident in all 4 species, but only 2 breeds of E.caballus expressed this trait - the Dutch Konik and Bosnian Mountain Horse. These 2 breeds were the only close descendants of the extinct Tarpan (Equus ferus ferus) represented in this study. In conclusion, the 2nd and 4th inte...
The brachioradialis is an important muscle that acts in the external rotation of the forearm (supination). However, its occurrence is controversial and little studied in the order Carnivora. Thus, this study investigates the occurrence and anatomo-functional arrangement of this muscle in wild carnivorans species. Fifty-eight thoracic limbs of specimens from species of Canidae, Procyonidae, Mustelidae and Felidae were dissected. Measurements of the length of the muscle (ML), the length of the forearm (FL), latero-medial width of the muscle (MW) and the lateral-medial diameter of the forearm (FD) were obtained to establish the ratios MW/FD and ML/FL in order to investigate the relative proportion of the muscle in relation to the forearm of each species. The brachioradialis muscle was identified in all species, although it was unilaterally or bilaterally absent in some canid individuals. The ratios demonstrated significant differences in the anatomical proportions among the families, with greater functional importance in the mustelids, procyonids, and felids because of a set of elaborate movements in the thoracic limb of representatives of these families when compared to canids.
Annals of Anatomy - Anatomischer Anzeiger, 2006
The hindlimb muscles in four species of Tenrecidae (Oryzoryctinae: Talazac longtailed tenrec and web-footed tenrec, Tenrecinae: lesser hedgehog tenrec, and streaked tenrec), were examined macroscopically. The weight ratios of the muscles to the body in the oryzoryctinid species are larger than those in Tenrecinae, since the Oryzoryctinae species have an obviously smaller body from the evolutionary point of view. It can be primarily pointed out that the adaptation of the body size is different between the two subfamilies, and secondarily, that functional adaptation to locomotion is complete within each subfamily. The weight data and the morphological findings demonstrate that the web-footed tenrec possesses an extraordinary large M. semimembranosus in comparison to the Talazac long-tailed tenrec in their weight ratios. This muscle may act as a strong flexor motor in the knee joint during the aquatic locomotion of the web-footed tenrec. Since the other muscles of the web-footed tenrec are similar to those of the Talazac long-tailed tenrec regards weight ratio data, we think that the web-footed tenrec may have derived from a terrestrial ancestor such as the long-tailed tenrecs. In Tenrecinae the streaked tenrec is equipped with larger Mm. adductores, M. semimembranosus and ARTICLE IN PRESS www.elsevier.de/aanat 0940-9602/$ -see front matter (H. Endo).
Arboreal locomotion imposes selective pressures that may affect the evolution of the locomotor apparatus. The limbs have to be mobile to reach across discontinuities, yet at the same time need to be forceful to move against gravity during climbing. However, as intermediaries between the arboreal and terrestrial environment, semi-arboreal mammals appear not extremely specialized and, thus, anatomical adaptations may be less evident than expected for arboreal climbers. Here, we present quantitative data on the muscle anatomy of the forelimbs (N 5 14) of two closely related species of Mustelidae and relate the findings to their loco-motor habits. The arboreal pine marten (Martes martes) and the more terrestrial stone marten (Martes foina) are the most similar sympatric carnivores in Europe, but distinctly differ in habitat selection and locomo-tor mode. Via dissections muscle architectural variables including muscle mass, pennation angle, and fiber length were measured and the physiological cross-sectional area and maximum isometric force were estimated for each muscle. The results reveal that the force-generating capacity of the limb flexor and retractor muscles and the excursion capability of the adductor muscles are greater in the pine marten compared to the stone marten. Since the two sympatric martens are very similar in terms of overall appearance, body size, intra-limb proportions, phylogenetic relationships and predation behavior, the differences in forelimb musculature are interpreted to reflect the greater climbing ability of the pine marten. The functional properties appear to facilitate locomotion in a three-dimensionally complex arboreal environment.