Adaptation of the hindlimbs for climbing in bears

Sasaki, Motoki; Endo, Hideki; Wiig, Øystein; Derocher, Andrew E.; Tsubota, Toshio; Taru, Hajime; Yamamoto, Masayuki; Arishima, Kazuyoshi; Hayashi, Yoshihiro; Kitamura, Nobuo; Yamada, Junzo

doi:10.1016/j.aanat.2004.10.001

Cited by 51 publications

(15 citation statements)

References 10 publications

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“…Mobility in multiple planes in the ankle joint is critical for arboreal locomotion in extant organisms [25], [70], [91]. All theropods have a mesotarsal ankle joint inherited from their ornithodiran ancestors, which consists of a simple, transversely oriented hinge with movement restricted to the anteroposterior plane [92].…”

Section: Resultsmentioning

confidence: 99%

“…A notable exception are the brachiating primates, whose locomotion is grip-based and unique among arboreal specialists. Paravian taxa also had long manual feathers that would not have permitted trunk hugging [96], as observed in some modern non-arboreal specialists such as bears and viverids [91], [97]. Thus non-avian theropods would have been unable to descend using either head or tail first methods, a necessary function in any pre-gliding non-avian taxa.…”

Section: Resultsmentioning

confidence: 99%

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Assessing Arboreal Adaptations of Bird Antecedents: Testing the Ecological Setting of the Origin of the Avian Flight Stroke

Dececchi

Larsson

2011

PLoS ONE

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The origin of avian flight is a classic macroevolutionary transition with research spanning over a century. Two competing models explaining this locomotory transition have been discussed for decades: ground up versus trees down. Although it is impossible to directly test either of these theories, it is possible to test one of the requirements for the trees-down model, that of an arboreal paravian. We test for arboreality in non-avian theropods and early birds with comparisons to extant avian, mammalian, and reptilian scansors and climbers using a comprehensive set of morphological characters. Non-avian theropods, including the small, feathered deinonychosaurs, and Archaeopteryx, consistently and significantly cluster with fully terrestrial extant mammals and ground-based birds, such as ratites. Basal birds, more advanced than Archaeopteryx, cluster with extant perching ground-foraging birds. Evolutionary trends immediately prior to the origin of birds indicate skeletal adaptations opposite that expected for arboreal climbers. Results reject an arboreal capacity for the avian stem lineage, thus lending no support for the trees-down model. Support for a fully terrestrial ecology and origin of the avian flight stroke has broad implications for the origin of powered flight for this clade. A terrestrial origin for the avian flight stroke challenges the need for an intermediate gliding phase, presents the best resolved series of the evolution of vertebrate powered flight, and may differ fundamentally from the origin of bat and pterosaur flight, whose antecedents have been postulated to have been arboreal and gliding.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Assessing Arboreal Adaptations of Bird Antecedents: Testing the Ecological Setting of the Origin of the Avian Flight Stroke

Dececchi

Larsson

2011

PLoS ONE

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“…Another alternative explanation for enhanced forelimb strength in Smilodon might be as an adaptation to climbing given that skeletal adaptations of the forelimbs for climbing and prey-killing are similar in felids [28]. However, the largest extant felids (lions, tigers) and ursid ( U. arctos ) rarely climb as adults, probably because their mass makes climbing too difficult and dangerous [48]–[50].…”

Section: Discussionmentioning

confidence: 99%

Radiographs Reveal Exceptional Forelimb Strength in the Sabertooth Cat, Smilodon fatalis

Meachen-Samuels

Valkenburgh

2010

PLoS ONE

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BackgroundThe sabertooth cat, Smilodon fatalis, was an enigmatic predator without a true living analog. Their elongate canine teeth were more vulnerable to fracture than those of modern felids, making it imperative for them to immobilize prey with their forelimbs when making a kill. As a result, their need for heavily muscled forelimbs likely exceeded that of modern felids and thus should be reflected in their skeletons. Previous studies on forelimb bones of S. fatalis found them to be relatively robust but did not quantify their ability to withstand loading.Methodology/Principal FindingsUsing radiographs of the sabertooth cat, Smilodon fatalis, 28 extant felid species, and the larger, extinct American lion Panthera atrox, we measured cross-sectional properties of the humerus and femur to provide the first estimates of limb bone strength in bending and torsion. We found that the humeri of Smilodon were reinforced by cortical thickening to a greater degree than those observed in any living felid, or the much larger P. atrox. The femur of Smilodon also was thickened but not beyond the normal variation found in any other felid measured.Conclusions/SignificanceBased on the cross-sectional properties of its humerus, we interpret that Smilodon was a powerful predator that differed from extant felids in its greater ability to subdue prey using the forelimbs. This enhanced forelimb strength was part of an adaptive complex driven by the need to minimize the struggles of prey in order to protect the elongate canines from fracture and position the bite for a quick kill.

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“…However, this hypothesis is at odds with the large body size of T. ornatus (with males reaching as much as 175 kg ; Nowak 1999), which precludes climbing on small arboreal supports in the way that lesser pandas do. In fact, among extant ursids, the radial sesamoid is not functionally involved at all in climbing behaviours, which are performed instead by relying on forelimb claws and the propulsive force generated by the hind limbs (Sasaki et al 2005). In contrast, spectacled bears show elaborate feeding activities, related to a very herbivorous diet that mostly relies on ripe fruits, bromeliad hearts, berries and palm hearts (Peyton 1980;Mondolfi 1989;Nowak 1999;Ríos-Uzeda et al 2006).…”

Section: Discussionmentioning

confidence: 99%

Tracing the origin of the panda’s thumb

Abellá

Pérez‐Ramos

Valenciano

et al. 2015

Sci Nat

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We investigate the relative development of the carnivoran radial sesamoids to untangle the evolution of this iconic structure. In the pandas (both giant and red), this 'false thumb' is known to perform a grasping role during bamboo feeding in both the red and giant pandas. An original locomotor role has been inferred for ailurids, but this remains to be ascertained for ursids. A large sample of radial sesamoids of Indarctos arctoides from the Miocene of Batallones-3 (Spain) indicates that this early ailuropodine bear displayed a relatively hypertrophied radial sesamoid, with a configuration more similar to that of the red panda and other carnivorans than to that of giant pandas. This false thumb is the first evidence of this feature in the Ursidae, which can be linked to a more herbivorous diet. Moreover, in the two extant pandas, the false thumb should not be interpreted as an anatomical convergence, but as an exaptive convergence regarding its use during the bamboo feeding, which changes the evolutionary view of this singular structure.

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Adaptation of the hindlimbs for climbing in bears

Cited by 51 publications

References 10 publications

Assessing Arboreal Adaptations of Bird Antecedents: Testing the Ecological Setting of the Origin of the Avian Flight Stroke

Assessing Arboreal Adaptations of Bird Antecedents: Testing the Ecological Setting of the Origin of the Avian Flight Stroke

Radiographs Reveal Exceptional Forelimb Strength in the Sabertooth Cat, Smilodon fatalis

Tracing the origin of the panda’s thumb

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