Re: News: Giant Dinosaurs Stuck Their Necks Out, Not Up?

On May 17, 5:09 pm, Ye Old One <use...@xxxxxxxxx> wrote:
Giant Dinosaurs Stuck Their Necks Out, Not Up?
Matt Kaplan
for National Geographic News
May 14, 2009http://news.nationalgeographic.com/news/2009/05/090514-dinosaurs-long...

Long-necked dinosaurs didn't graze treetops, according to new research
that suggests the prehistoric animals were better off holding their
necks horizontal, not upright.

Lifting long necks at steep angles would have put intense pressure on
sauropod hearts, requiring dramatic expenditures of energy to keep
blood pumping to the brain, a new study of dinosaur circulation says.

Sauropods were giant, long-necked, long-tailed, four-legged
plant-eaters that lived about 200 to 66 million years ago (prehistoric
time line).

Since long-necked modern animals, such as giraffes, tend to browse on
leaves in tall trees, paleontologists have assumed that
sauropods—whose necks could be as long as 30 feet [9 meters]—must have
done the same.

But Roger Seymour, of the University of Adelaide in Australia, found
that sauropods would have spent as much as 75 percent of their bodies'
energy to keep their heads held high.

Most mammals use about 10 percent of their energy to circulate blood
through their bodies. Giraffes use about 18 percent of their energy to
keep blood moving through their long, upright necks.

"Would the increased availability of food in tall trees be worth the
cost? This seems doubtful," Seymour said. "It would probably make more
energetic sense for [sauropods] to feed with their necks close to
horizontal."

By moving their necks side-to-side horizontally, sauropods would have
been able to feed on a very large area of plant material without
having to move their bodies.

That may not seem like a much of an energy-saving tactic. But in
animals that may have weighed 30 to 40 tons, the energetic difference
between taking a few steps and not taking a few steps may have been as
huge as the animals themselves.

Expensive Treats

Still, some scientists not involved with Seymour's research argue
that, in extreme cases, it may have been worth it for saurpods to
spend the extra energy to lift their necks.

The bones and joints in some of these animals show that they could
lift their necks between 30 and 60 degrees above horizontal,
paleontologist Martin Sander, of the University of Bonn in Germany,
said.

When food availability at low and medium heights became scarce, the
cost of raising the head to get valuable resources may have been worth
it, Sander said.

Richard Cowen, of the University of California, Davis, noted that
other animals sometimes expend enormous amounts of energy on food.

Cheetahs, for example, sprint after prey, even though the big cats
only make the catch one time in four. Likewise, whales use massive
amounts of energy to dive deep into cold water, and migratory birds
burn heaps of energy flying thousands of miles.

All of these behaviors could be viewed as incredible energy sinks, but
we know they are not because the animals gain something significant in
return that makes the energy expenditure worth it, Cowen explained.

"It would be reasonable for sauropods to browse occasionally with
heads high, as long as the payoff was also high," Cowen said.

Findings to be published in the June 23, 2009, edition of the journal
Biology Letters.

--
Bob.

no no no, you've just been fooled. Dinosaurs were never really alive,
they're just rock like bones put there to fool us, or maybe they're
still alive! or maybe the bible can help, since dinosaurs lived
alongside mankind....!

But seriously, i love the article. Makes sense, really. I have to
wonder how much energy would have been burned by the back muscles to
get the head up that high, since the neck muscles would have been
anchored to the back.

.

Relevant Pages

  • Re: News: Giant Dinosaurs Stuck Their Necks Out, Not Up?
    ... that suggests the prehistoric animals were better off holding their ... energy to keep their heads held high. ... keep blood moving through their long, upright necks. ... animals that may have weighed 30 to 40 tons, ...
    (talk.origins)
  • Re: News: Giant Dinosaurs Stuck Their Necks Out, Not Up?
    ... that suggests the prehistoric animals were better off holding their ... energy to keep their heads held high. ... keep blood moving through their long, upright necks. ... animals that may have weighed 30 to 40 tons, ...
    (talk.origins)
  • Re: News: Giant Dinosaurs Stuck Their Necks Out, Not Up?
    ... Long-necked dinosaurs didn't graze treetops, ... Lifting long necks at steep angles would have put intense pressure on ... Since long-necked modern animals, such as giraffes, tend to browse on ... energy to keep their heads held high. ...
    (talk.origins)
  • Re: News: Giant Dinosaurs Stuck Their Necks Out, Not Up?
    ... energy to keep their heads held high. ... keep blood moving through their long, upright necks. ... energetic sense for [sauropods] to feed with their necks close to ... animals that may have weighed 30 to 40 tons, ...
    (talk.origins)
  • Re: News: Giant Dinosaurs Stuck Their Necks Out, Not Up?
    ... energy to keep their heads held high. ... keep blood moving through their long, upright necks. ... energetic sense for [sauropods] to feed with their necks close to ... animals that may have weighed 30 to 40 tons, ...
    (talk.origins)