In our modern world, there are three major groups of mammals: placentals (that’s most of us), marsupials, and the rare and bizarre monotremes. Today’s monotremes – that’s echidnas and platypuses – are famous for their seemingly “un-mammalian” features: they lack external ears, they deliver milk without nipples, and they even lay eggs! This episode, we discuss what makes monotremes unique, the many questions still unanswered about their ancient history, and whether or not they are truly good representatives of early mammal evolution.

In the news: weird mosasaur teeth, Tibetan sabertooths, marsupial growth, and giant pliosaurs.

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The Intro and Outro music is “On the Origin of Species” by Protodome.

Musical Interludes are "Professor Umlaut" by Kevin MacLeod (incompetech.com). Licensed under Creative Commons: By Attribution 3.0