The great groups of placental mammals

  • Confirming four great clades of placental mammals. Briefly, the four great groups are

    Of course, the challenge is to fit fossil placental mammals (for which we have no DNA) into the scheme. A major implication of the classification is that mammal evolution was strongly affected by geography. This is not a surprise, but the extent of the dependence is surprising (to me).

    Molecular Clocks

    By 2004, people were saying that if you forget the idea of a strictly accurate molecular clock, and massage enough data, and rely on fossils for calibrating geological time, you can end up with something you believe. Molecular and fossil data can be "partially reconciliated", in the immortal phrase of the authors.

    Douzery, E. J. P., et al. 2004. The timing of eukaryotic evolution: Does a relaxed molecular clock reconcile proteins and fossils? PNAS 101: 15386-15391.

    The Paleocene/Eocene boundary

    The arrival of modern mammals in North America at 55 Ma. Research program of Christopher Beard.

    The Eocene

    The Fossils of Messel

    Ecological Replacement: The Guild Concept

    Cenozoic Mammals in Dinosaur Guilds

    Evolution by Improvement



    Walking sea-cows!!
    While we're talking about origins of marine mammals, how about the discovery of a fossil sea cow with legs? National Geographic News, October 11, 2001.

    Sea Sloths!
    While we're talking about origins of marine mammals, how about the discovery of sea sloths. Blog by Carl Zimmer, June 2004.


    P 253. Carnivorous deer. For the deer that eat baby birds, see this Web page

    References for Chapter 17

    This page last updated April 8, 2013

    Links last checked October 5, 2005.

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