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Article Dans Une Revue Zoological Journal of the Linnean Society Année : 2019

The earliest well-documented occurrence of sexual dimorphism in extinct sloths: evolutionary and palaeoecological insights

Résumé

Sexual dimorphism (SD) is extremely common in species that have reproductive roles segregated into separate sexes, and it has been recognized in several mammalian lineages, both extant and extinct. Sexual dimorphism is low to moderate in living sloths, but it had a more important role for extinct sloth taxa. The presence of SD in extinct sloths was first suggested at the end of the 19 th century and it is now commonly advocated as a possible explanation of high intraspecific variation in many extinct sloth species. In this paper, we report the presence of SD in Simomylodon uccasamamensis, a Late Miocene to Late Pliocene sloth from the Bolivian Altiplano. We present evidence of SD in the morphology of cranial and postcranial remains, representing the earliest unequivocal occurrence of size-based SD in an extinct sloth species. Differences between sexes are mainly observed in the morphology of the feeding apparatus and general body size. Comparisons with extant large mammals allow us to hypothesize different food selection between the two sexes, with probable divergent habitat use and concomitant niche separation. This, in turn, could have represented an important selective factor for adaptation to environmental changes experienced by the Bolivian Altiplano in Late Neogene times.
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Dates et versions

hal-03450407 , version 1 (14-12-2021)

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Alberto Boscaini, Timothy J Gaudin, Néstor Toledo, Bernardino Mamani Quispe, Pierre-Olivier Antoine, et al.. The earliest well-documented occurrence of sexual dimorphism in extinct sloths: evolutionary and palaeoecological insights. Zoological Journal of the Linnean Society, 2019, ⟨10.1093/zoolinnean/zlz011⟩. ⟨hal-03450407⟩
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