The emergence and demise of giant sloths.
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| Title: | The emergence and demise of giant sloths. |
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| Authors: | Boscaini, Alberto, Casali, Daniel M., Toledo, Néstor, Cantalapiedra, Juan L., Bargo, M. Susana, De Iuliis, Gerardo, Gaudin, Timothy J., Langer, Max C., Narducci, Rachel, Pujos, François, Soto, Eduardo M., Vizcaíno, Sergio F., Soto, Ignacio M. |
| Source: | Science. 5/22/2025, Vol. 388 Issue 6749, p864-868. 5p. |
| Subjects: | Sloths, Fossil herbivores, Cenozoic paleontology, Macroevolution, Mammal evolution |
| Abstract: | The emergence of multi-tonne herbivores is a recurrent aspect of the Cenozoic mammalian radiation. Several of these giants have vanished within the past 130,000 years, but the timing and macroevolutionary drivers behind this pattern of rise and collapse remain unclear for some megaherbivore lineages. Using trait modeling that combines total-evidence evolutionary trees and a comprehensive size dataset, we show that sloth body mass evolved with major lifestyle shifts and that most terrestrial lineages reached their largest sizes through slower evolutionary rates compared with extant arboreal forms. Size disparity increased during the late Cenozoic climatic cooling, but paleoclimatic changes do not explain the rapid extinction of ground sloths that started approximately 15,000 years ago. Their abrupt demise suggests human-driven factors in the decline and extinction of ground sloths. Editor's summary: Today, there are six species of sloths, all of which have similar ecologies such as arboreality and a slow metabolism. These species are a tiny remnant of a once diverse American clade that was mostly made up of large-bodied species. Boscaini et al. looked across the evolutionary history of sloths and reveal that the ancestral groups were terrestrial and large, with smaller species being derived and convergent. For 30 million years, the sloth family diversified across the Americas, from a species as large as an elephant to one that was entirely aquatic. Unfortunately, like most other large Pleistocene herbivores, the clade was almost entirely eradicated by newly arriving humans. —Sacha Vignieri [ABSTRACT FROM AUTHOR] |
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| Database: | Psychology and Behavioral Sciences Collection |
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| Abstract: | The emergence of multi-tonne herbivores is a recurrent aspect of the Cenozoic mammalian radiation. Several of these giants have vanished within the past 130,000 years, but the timing and macroevolutionary drivers behind this pattern of rise and collapse remain unclear for some megaherbivore lineages. Using trait modeling that combines total-evidence evolutionary trees and a comprehensive size dataset, we show that sloth body mass evolved with major lifestyle shifts and that most terrestrial lineages reached their largest sizes through slower evolutionary rates compared with extant arboreal forms. Size disparity increased during the late Cenozoic climatic cooling, but paleoclimatic changes do not explain the rapid extinction of ground sloths that started approximately 15,000 years ago. Their abrupt demise suggests human-driven factors in the decline and extinction of ground sloths. Editor's summary: Today, there are six species of sloths, all of which have similar ecologies such as arboreality and a slow metabolism. These species are a tiny remnant of a once diverse American clade that was mostly made up of large-bodied species. Boscaini et al. looked across the evolutionary history of sloths and reveal that the ancestral groups were terrestrial and large, with smaller species being derived and convergent. For 30 million years, the sloth family diversified across the Americas, from a species as large as an elephant to one that was entirely aquatic. Unfortunately, like most other large Pleistocene herbivores, the clade was almost entirely eradicated by newly arriving humans. —Sacha Vignieri [ABSTRACT FROM AUTHOR] |
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| ISSN: | 00368075 |
| DOI: | 10.1126/science.adu0704 |
