- PARIS (AFP) -- For more than
a century and a half, the flying reptiles known as pterosaurs have been
victims of a nasty smear, scientists say.
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- These cousins of the dinosaur are typically portrayed
as cawing, gawky fliers with all the agility of a World War I biplane.
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- Now, though, computer scanning of fossilised pterosaur
skulls has thrown up a radically different picture: of a creature whose
highly specialised brain gave it extraordinary control over its wing surfaces,
making it so nimble that it could probably outperform modern birds.
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- Researchers led by Lawrence Witmer of Ohio University
carried out high-resolution X-ray computer tomography to build a 3D image
of the skulls of two pterosaurs.
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- One was of Rhamphorhynchus, a long-tailed, crow-sized
creature that lived between 163 and 144 million years ago.
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- The other was of Anhanguera, a large pterosaur with a
short tail which lived during the Lower Cretaceous period, between 144
and 97.5 million years ago, and which was a close relative of the pterodactyl.
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- Compared to their mass, the brain that filled the skulls
of these first vertebrate fliers would have been smaller than that of modern
birds, Witmer's team say.
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- The likely reason for this is that birds descended from
relatively big-brained theropod dinosaurs, whereas pterosaurs' inherited
their grey matter from smaller-brained reptiles known as archosaurs.
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- But the pterosaurs' big plus was to have outsized brain
organs called the floccular lobes, which play a big role in processing
sensory data, and semi-circular canals, which encircle those lobes and
are important in providing balance.
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- Witmer's team suggests that the pterosaurs' "enormous"
lobes were used to process information sent back to the brain from sensors
on from their wings.
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- Pterosaurs did not have feathers - they had a membrane
of skin that stretched from their claw-like thumb and over its fingers.
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- Exciting recent finds of pterosaurs in Germany and China
show that these membranes, far from being insensitive and leather-like,
were remarkably complex, comprising a web of structural fibres, blood vessels
and fine muscles.
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- So by fine-controlling the shape of their wings, the
creatures could exploit even the slightest breeze to make tight turns and
swooping dives, all at a low cost in energy.
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- "Equipped with their 'smart' wings, pterosaurs would
have excellent flight control," David Unwin, a paleontologist of the
Museum of Natural Science at Berlin's Humboldt University, said in a commentary.
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- "Despite their antiquity, they could even have outperformed
modern birds and bats."
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- Copyright 2003 News Limited.
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- http://www.news.com.au/common/story_page/0,4057,7712734%255E1702,00.html
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