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Science

Dinosaur Posture Still Wrong, Says Study 226

Posted by kdawson
from the sit-up-straight dept.
An anonymous reader sends along a piece in Cosmos about new dissension to the current prevailing wisdom on dinosaur posture. The researchers admit that blood pressure presents an unresolved obstacle to their model of dinosaur heads held high. "The current depiction of the way giant sauropod dinosaurs held their necks is probably wrong, says a new study. 'For the last decade the reigning paradigm in palaeontology has been that the big sauropod dinosaurs held their necks out straight and their heads down low,' said co-author Matt Wedel, who researches biomechanics at the Western University of Health Sciences in Pomona, California. But 'our research [now] suggests that this view of sauropods is simply incorrect, based on everything we know about living animals,' he said." The researchers worried that some other team might beat them to publication, so obvious did they consider their methodology of looking at living animals to gain insight into the biomechanics of extinct ones.
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Dinosaur Posture Still Wrong, Says Study

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  • geese (Score:5, Interesting)

    by Red Flayer (890720) on Tuesday June 02, 2009 @01:52PM (#28185939) Journal
    Well, that was a quick slashdotting. Hopefully they'll be back up soon.

    Re: modern pseudo-analogues -- based upon the geese I raised as a kid, I never could quite grok the 'head-held-low' posture. Geese only hold their heads low to screw or to attack. It seems very inefficient for a large creature to hold that much weight horizontally away from the body (remember those physics lessons re: levers and distance from the fulcrum?).

    Dinosaurs are awesome, as most five-year-olds will tell you. Armchair paleontology is fun too. And since we slashdotters are so fond of pretending expertise on subjects we know little about, and TFA seems to be slashdotted, I'm looking forward to a very amusing (but maybe not quite so enlightening) discussion.
  • Re:Two Things (Score:2, Interesting)

    by MaXintosh (159753) on Tuesday June 02, 2009 @01:59PM (#28186057)
    Clone them, or get some better impressions of soft tissue. I expect we'll eventually get some, given our history of finding such neat things, but I'm not holding my breath because it's like finding a needle in a haystack.
    Er, well, actually more like finding a rock among a planet full of other rocks.
  • by Red Flayer (890720) on Tuesday June 02, 2009 @01:59PM (#28186063) Journal

    So, I'm suggesting that the long neck is held vertically as a way of gaining extra height for food reach, reaching the ground, and longer range vision without the increased bulk of longer legs, taller body, etc.

    Not only that, but I'd conjecture that the long neck must have evolved vertically. The musculature required to hold a long neck like that horizontal must be enormous, and hardly an efficient way of bearing weight. Plus, is it any coincidence that the large dinosaur neckbones look kind of like hip bones, the primary vertical weight-bearing bone in people?

    And the BS about the massive tail counterbalancing a long neck... for that to work as an opposing force on the neck, with the body as a fulcrum... well... that would required the spine to be pretty rigid. I'm not sure how well that would work in practice.

    On a side note, have you ever seen a giraffe try to reach the ground with their head? It's pretty amusing. It reminds me of myself, trying to pick up my kids crayons from the floor... it's a whole lot of effort (what? so I'm not in shape or flexible. That's normal here, right?)

  • by TinBromide (921574) on Tuesday June 02, 2009 @02:04PM (#28186103)
    Since I couldn't get to the article (still can't), I was extrapolating the posture of living long necked animals. Off hand, I can't think of any long necked animals that don't keep it in a vertical configuration, it seems like it'd be a waste to have a long neck without the defensive/food advantages that go along with it. It'd be like bats evolving wings, but not having the pectoral muscles to flap them enough to fly.
  • Re:Two Things (Score:3, Interesting)

    by techess (1322623) on Tuesday June 02, 2009 @02:42PM (#28186639)

    I agree until we get a better idea of the soft tissue we won't really know.

    Giraffes have a very cool way of improving their circulation without just throwing a bigger heart at the solution:
    http://news.softpedia.com/news/Some-Weird-Giraffe-Issues-80555.shtml [softpedia.com]

    "To pump the blood high to the brain, the heart of the giraffe is very large: up to 11 kg (25 pounds). The heart pushes 60 liters of blood per minute. The muscles of the neck arteries are relaxed with each heart beat, helping the propulsion of the blood to the brain. In the neck veins, special valves impede the blood to flow back too rapidly, meanwhile preventing the emergence of a syncope (fainting due to sudden lowering of the blood pressure). At the base of the feet, where pressure is low, there is a system of capillary vessels like in humans, impeding the appearance of edemas. Like humans, the giraffe is one of the few vertebrates which is taller than longer, and NASA studied blood circulation in giraffes for creating an anti-gravity garment for astronauts."

    Also horses while not having an extremely long neck also deal with circulation problems by more than throwing in a bigger heart.
    http://en.wikipedia.org/wiki/Circulatory_system_of_the_horse [wikipedia.org]
    The frog
    Each hoof contains a structural component known as the "frog," which covers the deeper structure of the hoof known as the digital cushion, a vessel-filled tissue. When the horse places weight on a leg, the ground pushes upward on the frog, compressing it and the underlying digital cushion. This results in squeezing blood out of the digital cushion, which then helps to pump it back up the leg, helping the heart to work against gravity.

    Nature has done some amazing and unique things with soft tissue to get around limitations. It would be so interesting to find out how dinosaurs worked and what their bodies were really like.

  • by Anonymous Coward on Tuesday June 02, 2009 @02:43PM (#28186641)

    yeah but the blood system is a (usually) closed system so the blood pumping up is offset somewhat by the blood coming down. it's a CIRCULATORY system !

    Blasted engineers, think ye know it all because you went to school for a while.

  • by Binestar (28861) * on Tuesday June 02, 2009 @03:27PM (#28187243) Homepage
    http://www.unmuseum.org/dinobront.htm [unmuseum.org]

    Today, scientist's vision of the habits and habitat of the Apatosaurus are quite different than what Marsh and other early paleontologists had thought. Early analysis suggested that the animals must have been weak because their small heads could only chew the minimum amount of food necessary to fuel such a big body. So weak, in fact, that large sauropods were thought to be slow, unable to lift their bulky tails off the ground and only able to support their massive weight by living in shallow lakes and swamps where water floated their bulk.

    Paleontologists like Bakker showed that this image was wrong. No Apatosaurus skeleton has been found in an ancient body of water and its feet were not at all suited for walking through marshy and muddy ground. In fact, Bakker notes in his book Dinosaur Heresies, an analysis of changes in geology over time suggest that large sauropods moved out of areas as they became wet: they didn't like swamps at all.

  • by wildsurf (535389) on Tuesday June 02, 2009 @03:38PM (#28187413) Homepage
    When thinking about dinosaurs' long necks, it's helpful to consider the possibility that the atmosphere was much thicker [dinosaurtheory.com] back then. So fluids could be drawn much higher without introducing vacuum problems, and it also explains how such huge insects and proto-birds (e.g. pterodactyls) could have flown there. Interesting stuff.
  • by Anonymous Coward on Tuesday June 02, 2009 @04:55PM (#28188561)

    When thinking about dinosaurs' long necks, it's helpful to consider the possibility that the atmosphere was much thicker

    Apparently, the atmosphere contained at least 30% oxygen (source: some Discovery documentary). Since the dinosaurs developed in this environment they must have been able to use the additional oxygen to their advantage. A slower blood flow could have transferred a reasonable amount of oxygen in this case.

    proto-birds (e.g. pterodactyls) could have flown there.

    Pterosaurs did have hollow bones in the same way modern birds have and the maximum wingspan of 10 meters is not so large considering the largest know bird, Argentavis magnificens, could have had a wingspan of 7 meters. Pterosaurs probably also had a larger effective wing area than modern birds considering the structures of bats and the (human) ideas of using the body of an airplane as a lifting surface in the form of flying wing, for example. These lifting structures would not necessary have survived in the fossilization process.

  • by init100 (915886) on Tuesday June 02, 2009 @04:56PM (#28188577)

    Not really, giraffe's have valves in their neck arteries -- hence you don't need insane amount of blood pressure from the heart (the valves keep the blood from falling down after being pushed up).

    Actually, most (all?) animals with a circulatory system have backflow prevention flaps in their veins. Having them in arteries is just a simple extension to this concept.

  • by rtb61 (674572) on Tuesday June 02, 2009 @07:50PM (#28190365) Homepage
    Of course if you had any dinosaurs left you could check to see whether major arteries were enclosed in musculature which assisted pumping the blood. Of course this evolutionary trait would be restricted only to major sauropods due to the inherent energy waste where it is not required and then perhaps only in the neck.
  • by Sulphur (1548251) on Tuesday June 02, 2009 @08:40PM (#28190689)
    If a few veins or arteries had peristalsis (distributed pumping), then the pressure difference could be less perhaps?

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