Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, Riverside, CA 92521, USA.
Curr Biol. 2022 Mar 14;32(5):R205-R210. doi: 10.1016/j.cub.2022.02.001.
Elephants and sea cows and tenrecs; hyraxes and aardvarks and sengis and golden moles. What do these very divergent and different looking mammals have in common? They are each other's closest living relatives, and all belong to the placental mammal clade Afrotheria ('African beasts'), which is one of the four major clades of placental mammals along with Xenarthra (anteaters, sloths, armadillos), Euarchontoglires (e.g. rodents, rabbits, primates), and Laurasiatheria (e.g. bats, carnivorans, odd-toed and even-toed ungulates) (Figure 1). Unlike many animal groups that were recognized and named long ago based on anatomical features, the Afrotheria emerged as a natural clade only in the 1990s when molecular techniques were applied to the problem of placental mammal classification. The recognition of Afrotheria represents a triumph of molecular phylogenetics and brings together a fantastically diverse assemblage of placental mammals with widely disparate ecological and morphological adaptations. Although Afrotheria was not previously proposed based on studies of anatomical characters, additional support for the monophyly of this clade comes from geography and the fossil record. Specifically, the six extant orders in Afrotheria share with each other early fossil representatives that are known from Africa or along the margins of the ancient Tethys Sea, hence Afrotheria.
大象、海牛和针鼹；蹄兔、土豚和穿山甲、金鼹。这些看起来非常不同的哺乳动物有什么共同点？它们彼此是现存的近亲，都属于胎盘哺乳动物进化枝 Afrotheria（“非洲兽类”），这是胎盘哺乳动物的四个主要进化枝之一，另外三个是 Xenarthra（食蚁兽、树懒、犰狳）、Euarchontoglires（例如啮齿动物、兔子、灵长类动物）和 Laurasiatheria（例如蝙蝠、食肉动物、奇数和偶数蹄类动物）（图 1）。与许多很久以前根据解剖特征识别和命名的动物群体不同， Afrotheria 作为一个自然进化枝，仅在 20 世纪 90 年代，当分子技术被应用于胎盘哺乳动物分类问题时才出现。 Afrotheria 的识别代表了分子系统发育学的胜利，并将具有广泛不同生态和形态适应的奇异多样的胎盘哺乳动物聚集在一起。尽管 Afrotheria 以前不是基于解剖学特征的研究提出的，但这个进化枝的单系性也得到了地理和化石记录的支持。具体来说， Afrotheria 中的六个现存目与彼此共享早期的化石代表，这些化石代表已知来自非洲或古特提斯海的边缘，因此称为 Afrotheria。
