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Science

Sexual Identification of A Rex Fossil 105

Posted by Zonk from the cranky-mother dept.
Rollie Hawk writes "The Tyrannosaurus rex has long been the darling of science fiction dinosaurs and has one of the most well-known skeletal designs among extinct creatures. But while even the most casual dinosaur enthusiast can identify the T. rex, until recently the sex of individual specimens was not discernable. Though dinosaurs are most known for their traits shared with modern reptiles, it is their kinship with birds that has finally revealed the sex of a T. rex fossil. To prepare for egg production, female birds develop a thick layer of medullary bone in their long bones, which acts as an extra source of eggshell calcium. According to Dr. Mary H. Schweitzer of North Carolina State University, the 'tyrant lizard king' appears to do the same thing. She explains that 'dinosaurs produced and shelled their eggs much more like modern birds than like modern crocodiles.'"
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Sexual Identification of A Rex Fossil More

Sexual Identification of A Rex Fossil

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  • They had sex? That would be some funny pr0n! (Score:1, Funny)

    by Anonymous Coward
    They had sex? That would be some funny pr0n!
  • So, anyone feel like digging through a pile of 1950s dinosaur movies to see just how many legendary T. Rex predators were, in fact, female?

    Are "errors" like this even gossip-worthy anymore? Damn bloody female empowerment movement.

    Something has to be done.
  • This could be just me and my will to believe everything in sci-fi movies, but can't the dinos assume either gender and reproduce? (Just like in Jurassic Park.) So why would these findings matter?

    • Re:Jurassic Park (Score:1, Informative)

      by Anonymous Coward
      In Jurassic Park the dinosaurs obtained that ability via frog DNA that was spliced in to fill the missing segments. In real life, we have no idea if they could do that or not. There's some likelyhood given the gender issues with birds, but we don't have complete DNA *or* intact specimens to even begin to guess.
    • Some frogs and fish can do this (even today), but I don't think we know of any dinosaurs that can do it. Well, maybe the Boy Georgeosaurus...


    • > This could be just me and my will to believe everything in sci-fi movies, but can't the dinos assume either gender and reproduce?

      Transvestite Rex?

    • In Jurassic Park, the DNA was combined with a frogs (or something similar - can't remember exactly) so that they could produce viable young. It was this frog part of the dino that allowed it to change gender.

  • Cool, but limitations. (Score:5, Informative)

    by Xeroc ( 877174 ) on Friday June 03, 2005 @11:51PM (#12721115)
    This is a cool achievement, but it does have limitations: (from the article)

    "This discovery will not enable paleontologists to determine the sex of all dinosaurs because medullary bone is present only during the egg-laying cycle. But when present, it at least enables scientists to say that a particular example is female.

    Not every museum may want to check the sex of its specimens because it requires cutting a long bone in half, said Horner, a co-author of the paper with Schweitzer.

    Even then, finding medullary bone is a long shot, Schweitzer said. First the dinosaur has to be an ovulating female. It also has to die before it has finished laying eggs and has to be fossilized. Finally, that fossil has to be found by humans."

    Unfortunately, this only means that a few specimens of them can be identified. It says that it's a damaging procedure, can only be used to determine femaleness and also, only works in a few cases.

    It also might be interesting to know that this particular dinosaur specimen was also the first specimen they were able to recover soft tissue from a dinosaur.
    • Right, but here's the other thing:

      Now that they have one way of determining gender, they could use that information to find out if there are other gender-specific traits.

      For example, if all the ones with the excess calcium have longer teeth, then they might be able to say that female T.Rex have longer teeth.

      Also, they should be able to figure out a non-invasive procedure to test the DENSITY of the bone without cutting it open. I mean, come on, isn't first year physics a requirement for all science degree

      • Re:Cool, but limitations. (Score:3, Insightful)

        by jd ( 1658 )
        Density, certainly. Archimedes figured that one out, and he didn't even take first-year physics.

        If the new bone is also off-center, or is not uniformly distributed, it would also change the center of mass, which would also be fairly easy to detect.

        Not sure what imaging techniques would work on fossilized bone, but since there may be organic matter inside the bone, then all you really need to do is image that and see what the gaps are. I don't know if any MRI techniques would be usable, such as somethin

        • Xray can work really well on fossil bone- I've gotten very nice X-rays from 75-million year old dinosaur bones, they show the bony network inside the bones (trabeculae, they're called)with as much detail as you'd get with a modern bone. However, Xray depends on density differences of the specimen, so if it's heavily impregnated with minerals you may not get much of an image.

          It's also increasingly common to use CT (computed tomography, which is basically 3d Xray) on fossils. However, CT is still pretty expe

    • Not every museum may want to check the sex of its specimens because it requires cutting a long bone in half

      That won't be a concern for long. Soon (10-20 years), we'll have the ability to molecularly "scan" objects by controlling swarms of nanites which work their way through it by recording and reconnecting the bonds. The amount of energy required to do this depends on the material (lattice enthalpy), and the resolution needed; the object is left in perfect condition as if it was never touched.

      On a rel

  • The Hunter (Score:2, Funny)

    by Tobril ( 202224 )
    We need to send Steve Irwin back in time, then we would learn all about dinosaur sex when he tries to molest them and gets eaten, that would have to be the best episode of the croc hunter ever.
  • link is here: http://www.npr.org/templates/story/story.php?story Id=4677825 [npr.org] I heard about it this morning. It sounds better over coffee.

  • deja-vu (Score:3, Insightful)

    by cgleba ( 521624 ) on Friday June 03, 2005 @11:58PM (#12721151)
    Damn. . .every program I hear on WBUR (NPR) has been showing up on slashdot three days later. . .
    • Well, what do you expect? Every story I findon Gizmodo is also on Engadget and 50 other big "tech" sites. The web is one big, gratuitous, incestuous, Caligulous orgy of informational fornication.

      • Re:deja-vu (Score:2, Funny)

        by simcop2387 ( 703011 )
        and slashdot needs to reverse the polarity to get rid of the feedback loop like other sites.
        • No, you dolt...we need to rotate the shield harmonics while simultaneously emitting a modified tachyon pulse through the forward deflector array.

          It's first year physics, people!
  • ...is that no one thought of this before now.

    Scientists have long known that dinosaurs have a kinship with birds even though they share traits with modern reptiles and many strides have been made in the field as a result of that knowledge.

    This news clearly has to be one of the finer examples we have where almost everyone is compelled to say "Damn, why didn't I think of that!"
    • is that no one thought of this before now.

      That is because it is too obvious. You see, in science you need to find the most complex way to solve a problem (it makes you sound smarter and you sounds like you know what you are talking about)
    • "The existence of avian-type MB in dinosaurs has been hypothesized (9, 23) but not identified. In part, this could be because of taphonomic bias, because the death and fossilization of an ovulating dinosaur would be comparatively rare. Additionally, MB in extant birds is fragile, the spicules separating easily from the originating layer (fig. S1). Dinosaur MB may separate and be lost from overlying CB in a similar manner during diagenesis."

      From the Science article, it's clear that fossilization most likely
  • Speaking of T-Tex and bones... Whatever happened to the soft tissue they found inside the T-rex bone they cut open a few months ago?

    • Re:Soft Tissue (Score:1, Insightful)

      by Anonymous Coward
      Not certain on this, but I believe this current find (the ability to determine the gender of the T-Rex) is related to the soft tissue find. It is the same Doctor, as well as the same University that made the initial discovery of the soft tissue. Furthermore, the dino that had the soft tissue was MOR-1125, and the dino that was determined to be female was also MOR-1125.
      • Yep. According to Science:

        "Unambiguous indicators of gender in dinosaurs are usually lost during fossilization, along with other aspects of soft tissue anatomy. We report the presence of endosteally derived bone tissues lining the interior marrow cavities of portions of Tyrannosaurus rex (Museum of the Rockies specimen number 1125) hindlimb elements,"


    • > Speaking of T-Tex and bones... Whatever happened to the soft tissue they found inside the T-rex bone they cut open a few months ago?

      I haven't seen the Science article, but the various on-line articles leave the impression that this "medullary bone" is the soft tissue they found a while back.

  • This means we can rest easy knowing that there will be NO accidental same sex marriages between Tyrannosaurs!

    Call the White House and Tom Delay.
  • Does that make the T. Rex backwards compatible with modern birds? or modern birds forward compatible with T. Rex eggs? Gaah, I've been following too much news spin on Longhorn.

    • Re:Compatible? (Score:2, Interesting)

      by dhasenan ( 758719 )
      Well, sort of--T. rex is a Saurischian, or lizard-hipped dinosaur, as are modern birds. (Actually, they've reverted to the other dominant hip type, which is why other dinosaurs are called Ornithischians, or bird-hipped.) Except that would be forward-and-to-one-side compatibility. Remember, kids, T. rex is a Coelurosaur, not a Carnosaur! Join our letter-writing campaign to correct two diagrams at the American Museum of Natural History today!
  • How big were dinosaur eggs?
    • Depends on the dinosaur now, doesn't it? You can't really ask "How big are bird eggs?" and expect a simple answer, can you?

      Dinosaurs varied from roughly chicken-sized to the huge sauropods. Titanosaurs, the family of the largest of all dinosaurs, laid spherical eggs about 15 cm in diameter.

  • I thought they were supposed to be studying T-Rex bones, not T-Rex boners.


  • So having big bones is a valid excuse for an overweight Mrs. T-Rex.

  • Staggering Odds (Score:3, Funny)

    by NitsujTPU ( 19263 ) on Saturday June 04, 2005 @01:22AM (#12721479)
    Even then, finding medullary bone is a long shot, Schweitzer said. First the dinosaur has to be an ovulating female. It also has to die before it has finished laying eggs and has to be fossilized. Finally, that fossil has to be found by humans.

    That last part is certainly a long shot for any bones lying undiscovered in a museum somewhere.
    • You aren't kidding. A lot of museums have no idea what exactly they have sitting around. How many years have the upper skulls of particularly interesting hominids sat, moldering in a museum archive, mislabled as turtle shells?
  • I'm from NC State. Here is the link to the original article at North Carolina State University.(including some pictures) http://www.ncsu.edu/news/press_releases/05_06/133. htm [ncsu.edu]
  • Skeletal design ? I'm guessing the poster was schooled in Kansas :-)
  • "it is their kinship with birds" Funny usage, as the birds are dinosaurs. Just as rodents are mammals.
    • That's some pretty... interesting logic. In what way are birds dinosaurs? Birds have feathers, wings, and an entirely different vascular system from dinosaurs. They share some similarities in bone structure and reproductive systems, but we cannot even confirm a genetic link due to the severe lack of dinosaur DNA (as in, NO DNA). While birds may be descended from dinosaurs, this does not make birds dinosaurs, any more than humans are fish.
  • Scientists also recently discovered what a female T-Rex's mating call would sound like. It is basically: Cacaw Cacaw Tookie Tookie Tookie. Cacaw Cacaw Tookie Tookie Tookie.
  • Occasionally, large collections of dinosaur bones are found at a single location, all of the same species, indicating that a group of these animals died in a single catastrophe. Sometimes these look like nesting sites. It will now be interesting to see if any of these groups can now be sexed.

    Of course, this method can only be used to determine if an individual was female if it was an ovulating female at the time of death; apparently, those that were not ovulating look just like males. Still, if we were to

  • dinosaurs produced and shelled their eggs much more like modern birds than like modern crocodiles.
    The Institute for Really Important Shit (tm) has uncovered evidence that dinosaurs produced and shelled their eggs much more like ancient dinosaurs than modern birds or crocodiles.
  • She explains "dinosaurs produced and shelled their eggs much more like modern birds than like modern crocodiles."

    Shouldn't that be:

    Modern birds, far more so than crocodiles, produce and shell their eggs like dinosaurs.

    -Nano.
  • A Tyrannosaurus stud
    Said "I don't have cold blood
    My kisses aren't mere pecks
    So, baby, let's have sex
    'Cause when I hear your moans
    I want to jump your medullary bones!"
  • So assuming that T Rex has similar mating cycles to modern birds, we probably not only know the gender of these fossils, but what time of year they died.

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