Brawn before brains in placental mammals after the end-Cretaceous extinction
Brawn before brains in placental mammals after the end-Cretaceous extinction
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DOI：
10.1126/science.abl5584
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发表时间：
2022-04-01
期刊：
影响因子：
56.9
通讯作者：
Brusatte, Stephen L.
中科院分区：
文献类型：
--
作者：
Bertrand, Ornella C.;Shelley, Sarah L.;Brusatte, Stephen L.
哺乳动物是脑化程度最高的脊椎动物，相对于身体大小，它们的大脑最大。有胎盘哺乳动物的大脑特别大，新皮层扩大，用于感觉整合，其起源尚不清楚。我们对新发现的古新世化石进行了计算机断层扫描，结果表明，与哺乳动物大脑随着时间的推移而稳步扩大的惯例相反，早期胎盘动物最初会减少其相对大脑大小，因为体重以更快的速度增加。在始新世后期，多个冠系通过感觉区域的显著增长独立地获得了高度脑化的大脑。我们认为，胎盘辐射最初强调增加身体大小的灭绝幸存者填补空缺的壁龛。随着生态系统的饱和和竞争的加剧，大脑最终变得更大。
Mammals are the most encephalized vertebrates, with the largest brains relative to body size. Placental mammals have particularly enlarged brains, with expanded neocortices for sensory integration, the origins of which are unclear. We used computed tomography scans of newly discovered Paleocene fossils to show that contrary to the convention that mammal brains have steadily enlarged over time, early placentals initially decreased their relative brain sizes because body mass increased at a faster rate. Later in the Eocene, multiple crown lineages independently acquired highly encephalized brains through marked growth in sensory regions. We argue that the placental radiation initially emphasized increases in body size as extinction survivors filled vacant niches. Brains eventually became larger as ecosystems saturated and competition intensified.