Mass estimation of Santacrucian sloths from the Early Miocene Santa Cruz formation of Patagonia, Argentina

Miocene deposits of the Santa Cruz Formation, Patagonia, comprise a diverse and excellently preserved vertebrate fauna, allowing detailed paleobiological and paleoecological studies based on three ecological parameters: body mass, diet, and substrate preference. In contrast to the small and arboreal...

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Autores principales: Toledo, Néstor, Cassini, Guillermo Hernán, Vizcaíno, Sergio Fabián, Bargo, María Susana
Formato: Articulo
Lenguaje:Inglés
Publicado: 2014
Materias:
Ciencias Naturales
Argentina
body mass
Folivora
Mammalia
Miocene
paleobiology
Santacrucian sloths
substrate preference
Xenarthra
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/85499
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-85499
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Ciencias Naturales
Argentina
body mass
Folivora
Mammalia
Miocene
paleobiology
Santacrucian sloths
substrate preference
Xenarthra
spellingShingle Ciencias Naturales
Argentina
body mass
Folivora
Mammalia
Miocene
paleobiology
Santacrucian sloths
substrate preference
Xenarthra
Toledo, Néstor
Cassini, Guillermo Hernán
Vizcaíno, Sergio Fabián
Bargo, María Susana
Mass estimation of Santacrucian sloths from the Early Miocene Santa Cruz formation of Patagonia, Argentina
topic_facet Ciencias Naturales
Argentina
body mass
Folivora
Mammalia
Miocene
paleobiology
Santacrucian sloths
substrate preference
Xenarthra
description Miocene deposits of the Santa Cruz Formation, Patagonia, comprise a diverse and excellently preserved vertebrate fauna, allowing detailed paleobiological and paleoecological studies based on three ecological parameters: body mass, diet, and substrate preference. In contrast to the small and arboreal extant sloths, Bradypus and Choloepus, Santacrucian sloths were much more diverse and larger, and comprised 11 genera previously characterized as arboreal or climbing forms. Here, we focus on body mass estimation based on measurements of postcranial elements. We present a morphometric database comprising 64 linear, base-ten logged variables applied to Santacrucian sloths and a wide sample of extant mammals, as well as the body mass of the extant taxa as reported in the literature. To detect any potential phylogenetical bias, we performed a variance decomposition test on our sample of extant mammals. Based on four orthogram statistics, logged body mass was found not to be dependent on phylogenetic tree topology. Predictive equations for the body mass of extant mammals were generated through multiple regression analysis, using weighting procedures to avoid taxonomic biases and stepwise analysis to discard redundant variables. Using this procedure, we derived separate equations for the scapula, humerus, radius, ulna, pelvis, femur, tibia plus fibula, astragalus, and calcaneum. These equations were then applied to estimate the body mass of our sample of Santacrucian sloths. We obtained an average body mass of about 70 kg for the megalonychid Eucholoeops. Among stem megatherioids, Hapalops ranged between 30 and 80 kg, Analcimorphus was estimated at 67 kg, and Schismotherium at 44 kg. Larger genera included the megatheriid Prepotherium (∼123 kg), and the mylodontids Analcitherium (∼88 kg) and Nematherium (∼89 kg). The medium to large body size of Santacrucian sloths imposed constraints on their climbing abilities. Megalonychids and stem megatherioids were likely unable to access the finest branches, while megatheriids and mylodonts were more terrestrial forms.
format Articulo
Articulo
author Toledo, Néstor
Cassini, Guillermo Hernán
Vizcaíno, Sergio Fabián
Bargo, María Susana
author_facet Toledo, Néstor
Cassini, Guillermo Hernán
Vizcaíno, Sergio Fabián
Bargo, María Susana
author_sort Toledo, Néstor
title Mass estimation of Santacrucian sloths from the Early Miocene Santa Cruz formation of Patagonia, Argentina
title_short Mass estimation of Santacrucian sloths from the Early Miocene Santa Cruz formation of Patagonia, Argentina
title_full Mass estimation of Santacrucian sloths from the Early Miocene Santa Cruz formation of Patagonia, Argentina
title_fullStr Mass estimation of Santacrucian sloths from the Early Miocene Santa Cruz formation of Patagonia, Argentina
title_full_unstemmed Mass estimation of Santacrucian sloths from the Early Miocene Santa Cruz formation of Patagonia, Argentina
title_sort mass estimation of santacrucian sloths from the early miocene santa cruz formation of patagonia, argentina
publishDate 2014
url http://sedici.unlp.edu.ar/handle/10915/85499
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