1. says

    They may well have been used in courtship displays.

    We do have one fossil allosaur with a damaged vertebra — it has a notch punched into it the same size as the tip of a stegosaur spike.

  2. jrkrideau says

    Having been slapped in the face by a cow’s tail I am must as glad they are not thagomizers.

  3. robro says

    Where have all the thagomizers gone, long time passing
    Where have all the thagomizers gone, long time ago
    Where have all the thagomizers gone, gone to fossils everyone
    When will we ever learn, When will we ev…er learn

    I couldn’t resist. Perhaps I’ll relearn the original and sing the revised version at a jam session.

  4. microraptor says

    In the instance of Doedicurus, one of the largest species of glyptodonts, it combined the bone club of the Ankylosaurs with the spikes of the Stegosaurs.

    Unfortunately, the high, rigid bony shell that protected Doedicurus also would have limited its field of vision, making it unlikely that it could have actively used its thagomizer to defend itself from predators. Damage to the armor shells appears consistent with impacts from the thagomizer, indicating that it was probably for intraspecies competition.

  5. microraptor says

    Also, I didn’t know that aardvarks would defend themselves by swinging their tails at attackers, I thought they primarily used their claws.

  6. says

    Kangaroos actually have large tendons stiffening their tail. To defend themselves they grab their attacker with their arms and use the tail as a brace while they bring their hind legs up to kick and disembowel the attacker. They can inflict some serious damage on a human

  7. Scott Simmons says

    Ah, yes. My family has a long history of involvement in dangerous science.

    My father once did a research study of the effectiveness of homework volume on learning in middle school students. I’d have stuck with studying large herbivore defensive weaponry, myself. But we Simmons’ are a hardy breed.

  8. Azkyroth, B*Cos[F(u)]==Y says

    My father once did a research study of the effectiveness of homework volume on learning in middle school students.

    J-curve with one inflection point? Or more?

  9. rietpluim says

    Do thagomizers have to be bony? Would it be possible for an animal to have a thagomizer made of keratin, like the horn of a rhinoceros?

  10. busterggi says

    There was a late Cretaceous line of enantiornithes that had thagomizers but they all starved to death because their tails were so heavy that they couldn’t move.

  11. Knabb says

    As far as tail weapons go there’s always scorpions. They’re smaller, but their stingers are at least as respectable for their size as ankylosaurs and their ilk.

  12. Rich Woods says

    Where have all the thagomizers gone?

    They were made redundant when the employment of dexitrobopers became fashionable.

  13. nomdeplume says

    PZ the business about length of tail, bony plates etc as necessary conditions, is a bit misleading. A species wouldn’t have those features in order to have a lump on the end of the tail, rather it would have a lump on the end of the tail (and therefore those features) if defending itself with its tail made ecological/behavioural sense. That is, if you are adapting to predators that hunt from behind by chasing, then tail defence might make sense, but with other predators (eg ambush ones) it wouldn’t. Similarly, competing for a mate depends on all kinds of behaviour patterns, some of which might fit with the tail as a weapon, others wouldn’t. There is a lot of energy investment in a big bony lump on a tail, and that investment only gets made if the result is superior adaptively to, say, a horn on the head.

  14. says

    Does the tail spike of a stringray count as a thagomizer? Or are venom delivery mechanisms a different category altogether from simple piercing / bludgeoning tail weapons?