The new framework for understanding placental mammal evolution
Article first published online: 6 JUL 2009
Copyright © 2009 Wiley Periodicals, Inc.
Volume 31, Issue 8, pages 853–864, August 2009
How to Cite
Asher, R. J., Bennett, N. and Lehmann, T. (2009), The new framework for understanding placental mammal evolution. Bioessays, 31: 853–864. doi: 10.1002/bies.200900053
- Issue published online: 16 JUL 2009
- Article first published online: 6 JUL 2009
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An unprecedented level of confidence has recently crystallized around a new hypothesis of how living placental mammals share a pattern of common descent. The major groups are afrotheres (e.g., aardvarks, elephants), xenarthrans (e.g., anteaters, sloths), laurasiatheres (e.g., horses, shrews), and euarchontoglires (e.g., humans, rodents). Compared with previous hypotheses this tree is remarkably stable; however, some uncertainty persists about the location of the placental root, and (for example) the position of bats within laurasiatheres, of sea cows and aardvarks within afrotheres, and of dermopterans within euarchontoglires. A variety of names for sub-clades within the new placental mammal tree have been proposed, not all of which follow conventions regarding priority and stability. More importantly, the new phylogenetic framework enables the formulation of new hypotheses and testing thereof, for example regarding the possible developmental dichotomy that seems to distinguish members of the newly identified southern and northern radiations of living placental mammals.