from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. A member of the Monotremata, an order of primitive egg-laying mammals restricted to Australia and New Guinea and consisting of only the platypus and the echidna.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A mammal that lays eggs and has a single urogenital and digestive orifice. Only the echidnas and platypuses are included in this group.
  • adj. Having a single trema, or aperture

from the GNU version of the Collaborative International Dictionary of English

  • n. One of the Monotremata.

from The Century Dictionary and Cyclopedia

  • Same as monotrematous: as, monotreme mammals; a monotreme egg.
  • n. A member of the Monotremata, as a duck-mole or prickly ant-eater.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. the most primitive mammals comprising the only extant members of the subclass Prototheria


from The American Heritage® Dictionary of the English Language, 4th Edition

From New Latin Monotrēmata, order name : mono- + Greek trēma, trēmat-, perforation.

from Wiktionary, Creative Commons Attribution/Share-Alike License

mono- +‎ -treme


  • The word monotreme combines the Greek words, μονο and τρεμα, for one and hole.


  • No, the label monotreme refers to the order of mammals which lay eggs. Stories / Popular

  • A 15 million-year-old complete skull and nearly complete dentition of the monotreme Obdurodon dicksoni has already provided a great deal of new information about this highly distinctive group of mammals.

    Australian Fossil Mammal Sites, Australia

  • Descriptions of the skull and non-vestigial dentition of a Miocene platypus (Obdurodon dicksoni n. sp.) from Riversleigh, Australia, and the problem of monotreme origins.

    Australian Fossil Mammal Sites, Australia

  • If moving from monotreme dreams to 'treme genes leaves you hungry for more information on Ornithorhynchus anatinus, reread this old Jurisdynamics post, Monotremata. posted by Jim Chen at 1:46 AM

    The platypus genome

  • But what the newly sequenced genome reveals is that the platypus's male-determining gene, the monotreme equivalent of primates' SRY gene, is not located on any of those five pairs of sex chromosomes.

    The platypus genome

  • June 4, 2008 at 11:54 am iz nawt mammul. iz….sumfin elze. big wurd. monotreme? sumfin liek dat.

    oh mai! - Lolcats 'n' Funny Pictures of Cats - I Can Has Cheezburger?

  • Imagine you are a future paleontologist who is spectacularly lucky and find the fossils representing the exact two species that were the progenitors of the monotreme and marsupials+placentals lineages.

    Mammalian Macroevolution Muddle - The Panda's Thumb

  • Somewhere deep, I actually knew that, but apparently I keep monotreme biology too deep to get to on short notice much like the junk at the bottom of all my closets

    Current Biology on flagellum evolution - The Panda's Thumb

  • But these fossils, even though they are from the true ancestral species of monotremes and marsupials+placentals, probably would not have any major distinguishing derived characters that would allow you to place either species specifically in the monotreme or marsupial/placental branch.

    Mammalian Macroevolution Muddle - The Panda's Thumb


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  • Did you see the caption on the accompanying photo (drawn from the main text)? It sounds like it came from a Gary Larson cartoon:

    "Muse Opiang was working as a field research officer when he became seized by a passion for the long-beaked echidna."


    June 10, 2009

  • LOL, bilby!

    ...except this particular species lives in New Guinea! ;)

    I think the Australian native species (are they called "short-beaked"?) are rather cuter. *fondly remembers meeting an Australian echidna many years ago*

    June 10, 2009

  • Strewth!

    Who wants to coin an adjective meaning "able to extrude a four-headed penis"?

    June 10, 2009

  • Australian know-how ;-)

    June 10, 2009

  • Seen in NYTimes today, a great article from which one sentence really popped out at me:

    "Yet through that uni-perforation, a male echnida can extrude a four-headed penis."

    Followed immediately by, "However they conduct their affairs, monotremes do it remarkably well."

    —Natalie Angier, "Brainy Echidna Proves Looks Aren’t Everything," New York Times, June 8, 2009

    June 10, 2009

  • Note that one needs to be careful with the use of primitive in this context. WordNet is not.

    March 8, 2008

  • I learned this word a minute ago on the platypus page.

    March 7, 2008