The Loom

Plagiarizing Dinosaurs

Effigia%20medium.jpgI’ve got an article in tomrrow’s New York Times about the discovery of a remarkable case of convergence: an ancient relative of today’s crocodiles and alligators that evolved a dinosaur’s body–80 million before the dinosaurs evolved it. Here’s the paper.

Update, 1/26 7 am: Here’s Seth Sean Murtha’s nice sketch of Effigia okeeffeae. A bigger version is here.


Update, 2/1 9 am: Be sure to check out Carl Buell’s croc gallery.


  1. #1 dearkitty
    January 26, 2006

    More on this here.

  2. #2 Clueless
    January 26, 2006

    The headline of the article was ‘Fossil Yields Surprise Kin of Crocodiles.’

    When I saw the headline, I was wondering how a fossil yield could surprise crocodiles (or their kin), and it took a few moments to figure out what it was intended to mean. Does the author have any control over the headline, or is it completely up to the editors at the newspaper?


  3. #3 Thomas R. Holtz, Jr.
    January 26, 2006

    Well, since the theropod dinosaurs eventually produced “crocodile mimics” of a sort (the Spinosauridae), it is only fair that the suchians produced a theropod mimic…

    In any case, Nesbitt & Norell’s work has shown that this clade of ostrich mimic mimics (*) were widespread. The more complete nature of Effigia‘s fossils allow several previously discovered fossils to be recognized as close relatives.

    Cool stuff.

    * Okay, REALLY they are ostrich mimic mimic mimics. There are ostriches, there are the Cretaceous ornithomimosaurs (colloquially the “ostrich mimics”), there is the ceratosaurian theropod Elaphrosaurus (an ostrich mimic mimic, but unfortunately with no known skull material), and now the chatterjeeids.

  4. #4 Chris Brochu
    January 26, 2006

    The problem is that things like Effigia came first – so it’s the ornithomimosaurs and Elaphrosaurus that are mimicking Effigia, not the other way around.

  5. #5 Thomas R. Holtz, Jr.
    January 26, 2006

    Chris is, of course, correct. So Elaphrosaurus is a chatterjeeid-mimic, ornithomimosaurs are chatterjeeid-mimic-mimics, and ratites are chatterjeeid-mimic-mimic-mimics.

  6. #6 Hai~Ren
    January 26, 2006

    The more I find out about Triassic critters, the more amazed I get. First _Revueltosaurus_ is a suchian, not an ornithischian, and now this.

    How close is this to that supposed Triassic “ornithomimosaur” _Shuvosaurus_? (Which now probably is indeed a non-dinosaurian archosaur after all) And hopefully the presence of a beak will also help explain the enigmatic nature of _Silesaurus_.

    And it does pose a question of whether this means that many fragmentary Triassic dinosaur specimens are simply chatterjeeids/silesaurids.

    And I do wonder if this will provide ammo for those in the birds-are-not-dinosaurs camp to show that convergent evolution for birds and theropods is possible. (No matter how easily disproven that would be)

  7. #7 David B. Benson
    January 26, 2006

    Thank you, Carl Zimmer, for the enlightening, not written-down, piece in TNYT on Triassic beasties named for one of my favorite artists.

    Not exactly related, how did the Triassic end? Big die-off?

  8. #8 Jacob
    January 26, 2006

    The Triassic did have a mass extinction at its end:

  9. #9 Thomas R Holtz, Jr.
    January 27, 2006

    Shuvosaurus is very likely a close kin of Effigia, according to Nesbitt & Norell. Additionally (as previously suggested by various authors), the postcranium Chatterjeea probably belongs to the skull Shuvosaurus (the latter name having priority).

    In contrast, Silesaurus does indeed seem to be very close to basal dinosaurs in terms of much of its anatomy. There are current research projects involving this archosaur in order to better establish its position.

    However, you are quite correct about the status of many Triassic dinosaurs. The last meeting of the Society of Vertebrate Paleontology had several talks which questioned the dinosaurian status of various Triassic “ornithischians”, “sauropodomorphs”, and

    The Late Triassic (or at least the Carnian and Norian stages–the final Rhaetian stage is less well understood) were a time in which many different lineages of synapsid “protomammals”, crurotarsans (incl. suchians), dinosauromorphs, and non-archosaurian diapsids were present. I don’t think that a naturalist from that time would necessarily have guessed that in the future Jurassic that dicynodonts, drepanosaurids and trilophosaurids would be extinct (for instance), but sauropodomorphs, crocodylomorphs, and turtles would have survived.

  10. #10 yonason
    October 21, 2007


    Wouldn’t that critter have to stand (quite a bit) more erect?

    Just compare the mass of the tail to that of the rest of it. Remember, it’s balanced on it’s hips. The tail is a counterweight to barely a fraction of the body from the hips to the snout.

    The way he’s drawn, he’s way off balance, especially not even standing on the equivalent of a foot, but rather on tip-toe, as it were. Although it may look like animals we are used to seeing (body parallel to the ground), it doesn’t make sense. Even if he were running very fast he would be hard pressed to keep from falling on his face.

    It may be a dramatic pose, but it isn’t very realistic.

    And it’s not a minor point, because the way an animal behaves is correlated to the way it carries itself. Properly viewing it’s posture can avoid many errors in deriving it’s habits.

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