Limb bone proportions, strength and digging in some Lujanian (Late Pleistocene-Early Holocene) mylodontid ground sloths (Mammalia, Xenarthra)

Bargo, M. Susana; Vizcaı́no, Sergio F.; Archuby, Fernando; Blanco, R. Ernesto

doi:10.1671/0272-4634(2000)020[0601:lbpsad]2.0.co;2

Cited by 111 publications

(107 citation statements)

References 17 publications

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“…The forelimb of these fossil sloths suggests that they were arboreal or semiarboreal forms with good digging capabilities, especially the mylodontids and Hapalops. As discussed in Toledo et al, (2012) and considering the inferred digging habits for Pleistocene ground sloths by Bargo et al, (2000), the evidence for good digging abilities in Santacrucian mylodontids would suggest a long phylogenetic history of digging habits for mylodonts.…”

Section: Paleobiological Inferencesmentioning

confidence: 96%

Muscular Reconstruction and Functional Morphology of the Forelimb of Early Miocene Sloths (Xenarthra, Folivora) of Patagonia

Toledo

Bargo

Vizcaı́no

2012

The Anatomical Record

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Early Miocene sloths are represented by a diversity of forms ranging from 38 to 95 kg, being registered mainly from Santacrucian Age deposits in southern-most shores of Patagonia, Argentina. Their postcranial skeleton differs markedly in shape from those of their closest living relatives (arboreal forms of less than 10 kg), Bradypus and Choloepus. In order to gain insight on functional properties of the Santacrucian sloths forelimb, musculature was reconstructed and a comparative, qualitative morphofunctional analysis was performed, allowing proposing hypotheses about biological role of the limb in substrate preferences, and locomotor strategies. The anatomy of the forelimb of Santacrucian sloths resembles more closely extant anteaters such as Tamandua and Myrmecophaga, due to the robustness of the elements, development of features related to attachment of ligaments and muscles, and conservative, pentadactylous, and strong-clawed manus. The reconstructed forelimb musculature was very well developed and resembles that of extant Pilosa (especially anteaters), although retaining the basic muscular configuration of generalized mammals. This musculature allowed application of powerful forces, especially in adduction of the forelimb, flexion and extension of the antebrachium, and manual prehension. These functional properties are congruent with both climbing and digging activities, and provide support for proposed Santacrucian sloths as good climbing mammals, possibly arboreal or semiarboreal, being also capable diggers. Their climbing strategies were limited, thus these forms relied mainly on great muscular strength and curved claws of the manus to move cautiously on branches. Anat Rec, 296:305-325,

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Section: Paleobiological Inferencesmentioning

confidence: 96%

Muscular Reconstruction and Functional Morphology of the Forelimb of Early Miocene Sloths (Xenarthra, Folivora) of Patagonia

Toledo

Bargo

Vizcaı́no

2012

The Anatomical Record

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“…Los fósiles son extremadamente escasos y muy fragmentarios exhibiendo una coloración oscura. Son abundantes las crotovinas de gran tamaño (diáme-tro >1 m, posiblemente asignables a grandes tardígrados; véase Bargo et al, 2000;Vizcaíno et al, 2001; Fig. 5, E y G), claramente delimitadas por concreciones calcáreas de considerable espesor y rellenas por sedimentos laminados o masivos (ocasionalmente por cenizas volcánicas de color pardo).…”

Section: Asociación De Facies 1 (Af 1)unclassified

Las sucesiones sedimentarias continentales expuestas en Centinela del Mar, provincia de Buenos Aires, Argentina (Pleistoceno Inferior-Holoceno)

Cenizo¹

2011

Est. Geol.

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RESUMENSon descriptas e interpretadas las características geomorfológicas y sedimentarias de las sucesiones continentales expuestas en los acantilados litorales y sectores aledaños de la localidad Centinela del Mar. Se definen catorce litofacies, cuyas relaciones, geometría y estructuras son representadas mediante perfiles transversales y longitudinales de detalle. En el sector basal y medio del perfil fueron reconocidas facies de distinto grado de transporte y retrabajo ácueo, en tanto, en el sector superior fue identificada una secuencia de facies marinas y perilitorales correspondientes a la transgresión «Belgranense» (=Fm. Pascua), culminando la sucesión facies eólicas relictuales. Las diferentes interpretaciones históricas son ampliamente discutidas, homologándose las unidades referidas previamente con las propuestas en este trabajo. Dichas unidades se correlacionan con aquellas definidas en el esquema aloestratigráfico propuesto para el área comprendida entre Playa San Carlos y Arroyo Chapadmalal. Esto permitió reconocer para el área bajo estudio la presencia de las Aloformaciones Punta San Andrés y Arroyo Lobería (sector basal-medio y cuspidal, respectivamente). Entre estas dos entidades, se intercala una asociación de facies marinas progradantes hacia ambientes perilitorales definidas y nominadas aquí como Aloformación Centinela del Mar. Finalmente, la información aquí reunida (magnetoestratigrafía, dataciones radiométri-cas, correlaciones estratigráficas, etc.) permite indicar, al menos preliminarmente, que la sucesión de Centinela del Mar corresponde al intervalo Ensenadense-Lujanense (Pleistoceno Inferior-Holoceno).Palabras clave: Litofacies, Estratigrafía, Geomorfología, Pleistoceno, Centinela del Mar, Buenos Aires, Argentina. ABSTRACTIn the present paper, the geomorphological and sedimentary characteristics of the continental sequences exposed on the coastal cliffs and surrounding areas of the Centinela del Mar locality are described and interpreted. Fourteen lithofacies are defined, their relation, geometry and structure are represented using transversal and longitudinal detailed profiles. In the basal and medium sector of the profile, facies of different degrees of transport and aqueous rework were recognized. In the superior sector, a succession of marine peri-coastal facies corresponding to the «Belgranense» transgression (=Fm. Pascua) were identified, ending the secuence with relictual eolic facies. The different historical interpretations are discussed, homologating the units referred previously with the ones proposed on this paper. These units are correlated with those defined in the allostratigrapic scheme proposed by other authors for the area covered between Playa San Carlos and Arroyo Chapadmalal. This allowed recognize for the area under study the presence of the Punta San Andrés and Arroyo Lobería Alloformations (basal-medium and superior sector, respectively). Between these two entities, a association of well defined progradant marine facies are found and named on this paper as Centine...

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“…The clade including Bradypus, according to the phylogenetic hypotheses of Gaudin (2004) and Pujos et al (2007) (see also McDonald & De Iuliis 2008), is currently only represented by the three-toed sloth, since no known or putative fossil bradypodids have been recorded. The diversity of fossil sloths encompassed arboreal, terrestrial, fossorial and aquatic or semiaquatic forms (McDonald & De Iuliis 2008, Pujos et al 2012Amson et al 2014Amson et al , 2015, with body masses ranging from dozens of kilograms to several tons (White 1993(White , 1997Fariña et al 1998;Bargo et al 2000;De Esteban-Trivigno et al 2008;Toledo et al 2014) (Fig. 1 Bargo et al 2012;Pujos et al 2016).…”

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confidence: 99%

Evolution of body size in anteaters and sloths (Xenarthra, Pilosa): phylogeny, metabolism, diet and substrate preferences

Toledo

Bargo²,

Vizcaı́no

et al. 2015

Earth and Environmental Science Transactions of the Royal Socie

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Pilosa include anteaters (Vermilingua) and sloths (Folivora). Modern tree sloths are represented by two genera, Bradypus and Choloepus (both around 4-6 kg), whereas the fossil record is very diverse, with approximately 90 genera ranging in age from the Oligocene to the early Holocene. Fossil sloths include four main clades, Megalonychidae, Megatheriidae, Nothrotheriidae, and Mylodontidae, ranging in size from tens of kilograms to several tons. Modern Vermilingua are represented by three genera, Cyclopes, Tamandua and Myrmecophaga, with a size range from 0.25 kg to about 30 kg, and their fossil record is scarce and fragmentary. The dependence of the body size on phylogenetic pattern of Pilosa is analysed here, according to current cladistic hypotheses. Orthonormal decomposition analysis and Abouheif C-mean were performed. Statistics were significantly different from the null-hypothesis, supporting the hypothesis that body size variation correlates with the phylogenetic pattern. Most of the correlation is concentrated within Vermilingua, and less within Mylodontidae, Megatheriidae, Nothrotheriidae and Megalonychidae. Influence of basal metabolic rate (BMR), dietary habits and substrate preference is discussed. In anteaters, specialised insectivory is proposed as the primary constraint on body size evolution. In the case of sloths, mylodontids, megatheriids and nothrotheriids show increasing body size through time; whereas megalonychids retain a wider diversity of sizes. Interplay between BMR and dietary habits appears to be the main factor in shaping evolution of sloth body size.

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Limb bone proportions, strength and digging in some Lujanian (Late Pleistocene-Early Holocene) mylodontid ground sloths (Mammalia, Xenarthra)

Cited by 111 publications

References 17 publications

Muscular Reconstruction and Functional Morphology of the Forelimb of Early Miocene Sloths (Xenarthra, Folivora) of Patagonia

Muscular Reconstruction and Functional Morphology of the Forelimb of Early Miocene Sloths (Xenarthra, Folivora) of Patagonia

Las sucesiones sedimentarias continentales expuestas en Centinela del Mar, provincia de Buenos Aires, Argentina (Pleistoceno Inferior-Holoceno)

Evolution of body size in anteaters and sloths (Xenarthra, Pilosa): phylogeny, metabolism, diet and substrate preferences

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