通过结合全证据进化树和综合尺寸数据集的特征建模，该团队发现树懒的体重随着主要生活方式的转变而进化，与现存的树懒相比，大多数陆生谱系通过较慢的进化速度达到了最大的体型。在晚新生代气候变冷期间，体型差异增加了，但古气候变化并不能解释大约15000年前开始的地懒的迅速灭绝。它们的突然灭绝表明，人类活动导致了地懒数量的减少和灭绝。
据悉，多吨食草动物的出现是新生代哺乳动物辐射的一个反复出现的方面。在过去的13万年里，这些巨兽中的一些已经消失了，但对于一些巨型食草动物谱系来说，这种崛起和崩溃模式背后的时间和宏观进化驱动因素仍然不清楚。
附：英文原文
Title: The emergence and demise of giant sloths
Author: Alberto Boscaini, Daniel M. Casali, Néstor Toledo, Juan L. Cantalapiedra, M. Susana Bargo, Gerardo De Iuliis, Timothy J. Gaudin, Max C. Langer, Rachel Narducci, Franois Pujos, Eduardo M. Soto, Sergio F. Vizcaíno, Ignacio M. Soto
Issue&Volume: 2025-05-22
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.
DOI: adu0704
Source: https://www.science.org/doi/10.1126/science.adu0704