The cheetah (Acinonyx jubatus) dewclaw: specialization overlooked

Londei, Tiziano

doi:10.1017/s095283690021813x

Cited by 9 publications

(11 citation statements)

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“…Nor does it satisfy the third criterion, because it retains the typical function of a finger with a sharp, curved ungual and claw: prehension. Its use is an important part of prey capture in felids ( Londei, 2000 ), and we have personally observed that domestic dogs use the dewclaw to snag and maintain a grip on objects. Its shortening is therefore not the reduction of an unused organ.…”

Section: Resultsmentioning

confidence: 99%

A critical survey of vestigial structures in the postcranial skeletons of extant mammals

Senter

Moch

2015

PeerJ

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In the Mammalia, vestigial skeletal structures abound but have not previously been the focus of study, with a few exceptions (e.g., whale pelves). Here we use a phylogenetic bracketing approach to identify vestigial structures in mammalian postcranial skeletons and present a descriptive survey of such structures in the Mammalia. We also correct previous misidentifications, including the previous misidentification of vestigial caviid metatarsals as sesamoids. We also examine the phylogenetic distribution of vestigiality and loss. This distribution indicates multiple vestigialization and loss events in mammalian skeletal structures, especially in the hand and foot, and reveals no correlation in such events between mammalian fore and hind limbs.

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Section: Resultsmentioning

confidence: 99%

A critical survey of vestigial structures in the postcranial skeletons of extant mammals

Senter

Moch

2015

PeerJ

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“…Multiple instances of incomplete loss such as remnants of the pelvis in cetaceans and eyes in blind cavefish may reflect progressively weaker selection on traits that are neither functional nor costly to produce [2], or possibly reflect developmental constraints on the capacity for independent loss of characters in an integrated system [3,4]. Alternatively, some rudimentary traits previously thought to have only marginal function, for example, the dew claw of wild felids and the human coccyx, may persist owing to skeleto-muscular and behavioural functionalities [5,6].…”

Section: Introductionmentioning

confidence: 99%

Neural network detected in a presumed vestigial trait: ultrastructure of the salmonid adipose fin

2011

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A wide variety of rudimentary and apparently non-functional traits have persisted over extended evolutionary time. Recent evidence has shown that some of these traits may be maintained as a result of developmental constraints or neutral energetic cost, but for others their true function was not recognized. The adipose fin is small, fleshy, non-rayed and located between the dorsal and caudal fins on eight orders of basal teleosts and has traditionally been regarded as vestigial without clear function. We describe here the ultrastructure of the adipose fin and for the first time, to our knowledge, present evidence of extensive nervous tissue, as well as an unusual subdermal complex of interconnected astrocyte-like cells equipped with primary cilia. The fin contains neither adipose tissue nor fin rays. Many fusiform actinotrichia, comprising dense striated macrofibrils, support the free edge and connect with collagen cables that link the two sides. These results are consistent with a recent hypothesis that the adipose fin may act as a precaudal flow sensor, where its removal can be detrimental to swimming efficiency in turbulent water. Our findings provide insight to the broader themes of function versus constraints in evolutionary biology and may have significance for fisheries science, as the adipose fin is routinely removed from millions of salmonids each year.

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“…The cheetah, the definitive cursorial cat, diverges from other felids toward the more cursorial region of the morphospace, reflecting its locomotor ecology and reorientation of the metacarpals—into a more fused, hinge‐type joint (Hopwood, ). The cheetah does retain the first metacarpal, including retention of a trapezium articulation, for a distinct purpose in prey acquisition; using their dewclaw (or first claw) to hook prey off balance (Londei, ), but it does not need to retain the flexibility as in other cats for gripping.…”

Section: Discussionmentioning

confidence: 99%

Locomotor correlates of the scapholunar of living and extinct carnivorans

Dunn

Cooper

Lemert

et al. 2019

Journal of Morphology

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The relationship of carpal morphology to ecology and habitat is under studied in carnivorans and more generally in mammals. Here, we use 3D‐scanning techniques to assess the usefulness of a carpal bone, the scapholunar, in carnivorans to reflect ecology and habitat, and to reconstruct the ecology of five extinct carnivorans from two fossil sites: Rancho La Brea and Natural Trap Cave. We 3D‐scanned scapholunars and measured articular surface areas and angles between articular facets using GeoMagic and Rhino 3D‐software. We analyzed the difference in these metrics using multivariate analysis of variance and discriminant function analysis. Results show that the scapholunar reflects ecological signal, with clear groupings of cursorial carnivorans and grappling/climbing carnivorans; however, phylogenetic signal was also present in the results with hyaenids, canids, and large felids in distinct morphospaces. Extinct species Miracinonyx trumani (American cheetah) and Smilodon fatalis (sabertooth cat) showed surprising results with M. trumani grouping with pantherines instead of Acinonyx or Puma, suggesting it runs but still retains the ability to grapple prey. S. fatalis groups with pantherines, but also shows some unique adaptations, suggesting it had a different range of wrist motion than living cats. Overall, the scapholunar is a good indicator of ecology and functional morphology and can be another tool to use in modern and fossil carnivorans to reconstruct extinct ecologies and locomotor behaviors.

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The cheetah (Acinonyx jubatus) dewclaw: specialization overlooked

Cited by 9 publications

References 0 publications

A critical survey of vestigial structures in the postcranial skeletons of extant mammals

A critical survey of vestigial structures in the postcranial skeletons of extant mammals

Neural network detected in a presumed vestigial trait: ultrastructure of the salmonid adipose fin

Locomotor correlates of the scapholunar of living and extinct carnivorans

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