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How Did Giant Dinos Neck it?

  • 17-05-2009 12:29am
    #1
    Registered Users Posts: 30,747 ✭✭✭✭ Galvasean


    'New research' suggests it was not energy efficient for sauropods (long necked dinosaurs) to hold their heads up high for grazing in tree tops and that holding them out horizontally would be a better use of said energy.
    Surely this was obvious? Have a read for yourself:
    http://news.nationalgeographic.com/news/2009/05/090514-dinosaurs-long-necks.html

    I don't really see why it's headline news to be honest. It has been known for quite some time that the likes of Diplodocus held their necks horizontally, while basic anatomy shows that some sauropods like Brachiosaurus did indeed hold their heads up high, albeit the latter is less common. Although in these cases they poossibly didn't raise their heads too far above shoulder height because it would be a problem to get blood fllowing straight up the neck to the head.
    However, it has been speculated that the giant dinosaurs' small brains (which required a relatively small amount of circulating blood) may have been advantageous while feeding from tall trees. A larger brain would require more blood flow, potentially inhibiting the creatures' ability to feed at such high altitudes (some 13 meters above the ground).
    It has also been speculated that a large sauropod lowering its neck quicky would result in a sudden rush of blood to the head which might daze the poor beast.

    Brachiosaurus.jpg


Comments

  • Registered Users Posts: 960 ✭✭✭ darjeeling


    Galvasean wrote: »
    'New research' suggests it was not energy efficient for sauropods (long necked dinosaurs) to hold their heads up high for grazing in tree tops and that holding them out horizontally would be a better use of said energy.

    Hold the presses - there's a fight on.

    In the news today, Portsmouth Uni palaeontologist Mike Taylor has a paper out (here) saying otherwise.

    [...] a substantial literature on extant amniotes (mammals, turtles, squamates, crocodilians and birds) shows that living animals do not habitually maintain their necks in ONP [(osteological neutral pose - i.e. the sauropod horizontal straight neck pose)]. Instead, the neck is maximally extended and the head is maximally flexed, so that the mid−cervical region is near vertical.

    In today's Guardian (here), he says:

    Unless sauropods carried their heads and necks differently from every living vertebrate, we have to assume that the base of their neck was curved strongly upwards. In some sauropods this would have meant a graceful, swan-like S-curve to the neck, and a look quite different from the recreations we are used to seeing today.

    Over at the London Nat Hist Museum, where they have a prized (and currently horizontally-necked) Diplodocus, palaeontologist Paul Barrett spoke to the BBC and the Guardian.
    BBC News wrote:
    (link here )

    Paul Barrett, a palaeontologist from London's Natural History Museum, thinks the sauropods were likely to have been able to lift their heads high, but he remains unconvinced that would have been their "resting posture".

    "It would require lots of muscular activity, and put a lot of strain on their hearts," he said.

    Dr Barrett explained that, since it is impossible to know how thick the pads of connective tissue between the dinosaurs' vertebrae were, it is difficult to estimate how much of a role this tissue, along with muscles and tendons, played in the animals' range of movement.

    "Sauropods are bizarre," he told BBC News. "There is no living animal built in the same way."

    And on the question of blood pressure, the Guardian article offers this:

    In a study published only last month, the Australian palaeontologist Roger Seymour calculated that if a sauropod held its head upright, it would use half of its energy pumping blood to its brain, requiring a two-tonne heart that would hardly fit inside its ribcage.

    But Taylor said the estimates of blood pressure were based on extrapolations from smaller animals, which he doesn't believe are valid for larger creatures.

    "It might be that the sauropods found a similar way around the problem as giraffes, but we have no way of knowing. We just can't tell with the sauropods, because they're all dead," said Barrett.


  • Registered Users Posts: 4,879 Coriolanus


    Saw this in the Times today too, think they got it from the Guardian world service though.

    Interesting stuff all round. Another thing there's apparently some retconing being done is legbone alignment. I was in the Milwaukee State Museum and their triceratops was postured like a gecko/komodo etc, typical lizard structure rather than what I'd always thought, a more mammalian, upright structure (like a horse I guess?)

    As in...
     _O_
    !   !
    

    instead of
     O
    ! !
    

    Erp, not to scale. But you get the idea!


  • Registered Users Posts: 30,747 ✭✭✭✭ Galvasean


    Nevore wrote: »
    Saw this in the Times today too, think they got it from the Guardian world service though.

    Interesting stuff all round. Another thing there's apparently some retconing being done is legbone alignment. I was in the Milwaukee State Museum and their triceratops was postured like a gecko/komodo etc, typical lizard structure rather than what I'd always thought, a more mammalian, upright structure (like a horse I guess?)

    As in...
     _O_
    !   !
    

    instead of
     O
    ! !
    

    Erp, not to scale. But you get the idea!

    Hmm, last I heard the komodo dragon like stance for Triceratops' front legs had gained favour over the more bird llike upright posture which had appeared in early illustrations. Something to do with Triceratops being able to turn and manouver quicker in a squating position. Does seem a bit strange that while most other dinosaurs had the upright stance, Triceratops would have the semi-sprawled stance.

    Saw a tiny article on the sauropod necks in the Metro (or possibly Herald AM, one of those free rags). Only gave the most basic of overviews, but was good to see palaeontology news in a well distributed newspaper anyway.


  • Registered Users Posts: 4,879 Coriolanus


    Ah, it was news to me. Haven't been keeping up to date I guess. :o

    It was probably the Metro, since I can't seem to find it in the Indo and they normally carry similarly syndicated articles to the Herald.

    Irish Times and Metro isn't a bad thing though.


  • Registered Users Posts: 30,747 ✭✭✭✭ Galvasean


    Science Centric have a good article on some of the research:
    http://www.sciencecentric.com/news/article.php?q=09052703-giant-dinosaur-posture-is-all-wrong
    Famous depictions of the largest of all known dinosaurs, from film and television to museum skeletons, have almost certainly got it wrong, according to new research. Sauropods are the most iconic of prehistoric creatures. They were up to 30 metres long, weighed as much as 10 elephants, and are instantly recognisable by their very long necks and small heads. They are the centrepieces in most natural history museums worldwide.

    Recent depictions such as the BBC's Walking With Dinosaurs show them with their long necks held horizontal and their heads near the ground. But now scientists are saying the low-necked sauropod pose is a mistake: new evidence indicates that they held their necks aloft like giraffes and all other living land vertebrates, making them up to 15 metres tall.

    Dr Mike Taylor and Dr Darren Naish, of the University of Portsmouth, and Dr Matt Wedel, of Western University of Health Sciences in California, argue that while sauropods could hold their necks low, it was not their habitual posture.

    They studied X-rays of members of 10 different vertebrate groups and found that while the neck is only gently inclined in salamanders, turtles, lizards and crocodilians, it is vertical in mammals and birds - the only modern groups that share the upright leg posture of dinosaurs.

    Dr Taylor said: 'Like the animals we have with us today, they would have spent most of their time with their necks elevated, except when drinking or browsing at low levels.'

    Modern vertebrates, from cats and humans to sauropods' closest living relatives, the birds, hold their necks aloft in a vertical or near-vertical position.

    Dr Wedel said: 'We can't just study fossil bones by themselves. Dinosaurs were living animals and to understand how they lived, we need to look at animals that are alive today. In this case, our evidence shows the present is the key to the past.'

    The neck vertebrae of sauropods fit together mainly by way of ball and socket joints. In addition, the top part of each vertebra has a pair of facets, two at the front and two at the back, which glide past each other when the neck bends.

    Dr Taylor said: 'Scientists have assumed that each pair of facets must maintain at least a 50 percent overlap at all times; but looking at what ostriches and giraffes do, we see that their facets can slide much further, until they hardly overlap at all. This means that sauropods would have had a far greater range of neck movement than has been thought in recent times.

    'Unless sauropods carried their heads and necks differently from every living vertebrate, we have to assume that the base of their neck was curved strongly upwards. In some sauropods this would have meant a graceful swan-like S-curve to the neck, and a look quite different from the recreations we are used to seeing today.'

    Low necked poses for sauropods have been used for countless plastic toys and have become part of mainstream culture, thanks in part to the BBC's Walking with Dinosaurs, and to new museum exhibits such as one at the American Museum of Natural History in New York.

    Professor Mike Benton at Bristol University's Department of Earth Sciences, said: 'It's hugely important to understand how sauropod dinosaurs functioned. They were so huge - ten times the size of an elephant - and yet they were successful animals. This new work provides plausible evidence that sauropods held their necks elevated, rather than horizontally, as had been assumed.

    'The new work is based on studies of living animals, but the next step will be to carry out engineering studies to see whether the new or old neck positions are energetically more efficient. If you have a long neck that weighs a tonne or more you must hold it in a neutral position where stresses and strains are minimised.'

    I noticed that Mike Benton is one of the commentators. He wrote most of the books I read as a kid. Nice to see he's still knocking about. :)
    Speaking of childhood, does this mean the Land Before time was right all along?


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