Posted on 03/15/2006 12:23:34 PM PST by The_Victor
LONDON (Reuters) - A newly discovered, perfectly preserved fossil of a 150 million-year-old dinosaur found in southern Germany may force scientists to rethink how and when feathers evolved.
The nearly complete remains of the chicken-size dinosaur named Juravenator, which is described in the journal Nature on Wednesday, were preserved in limestone. But unlike other members of the group of two-legged meat-eating predators known as coelurosaurs, it had no feathers.
"It is an absolutely new dinosaur that was not known before," said Ursula Gohlich, a palaeontologist at the University of Munich in Germany.
Remains of small dinosaurs from the Late Jurassic period are rare finds. The new fossil is nearly complete, apart from a missing part of its long tail, and shows soft tissue and an imprint of the skin but no feathers.
"Scientists had thought that all representatives of the group coelurosaurs should have feathers," Gohlich told Reuters.
"Now we have a little dinosaur that belongs to coelurosaurs that does not show feathers. This is a problem."
COMPLEX EVOLUTION
Feathers were thought to have evolved very early within coelurosaurs. All members of the group were thought to be feathered.
But Gohlich and Luis Chiappe, of the Natural History Museum of Los Angeles County in California, believe the evolution of feathers may be more complex than previously thought.
Feathers may have evolved early but then were replaced by scales in some creatures because they were not needed.
"Another possibility perhaps is that some representatives of coelurosaurs were not entirely covered with feathers, only certain areas," said Gohlich.
The newly discovered Juravenator was very young so may not have lived long enough to develop feathers. But Gohlich said that despite its age, she would have expected it to have had feathers.
"We think that feathers evolved. We have several fossils that support this theory. But our fossil asks some questions," she added.
The oldest known bird, Archaeopteryx, was also found in southern Germany. It too lived about 150 million years ago and had feathers but it is uncertain whether they were used to fly or to keep warm.
Xing Xu, of the Chinese Academy of Sciences in Beijing, said whatever the explanation, the discovery of Juravenator has enriched knowledge of early feather evolution. It could also indicate where future research could be concentrated.
"Juravenator may complicate the picture, but it makes it more complete and realistic," he said in a commentary in the journal.
Maybe it died from a disease that made its feathers fall out; or maybe it died after moulting. Hard to draw firm conclusions based on a single data point.
Yup. Ignoring evidence that doesn't fit is an exorcise for the ignorant.
I hate typos that are real words.
exorcise=exercise
The scientists said this was an exciting discovery because these partial footprints belonged to an aqauatic dinosaur, that was a vegetarian, and a precursor to birds.
I said "Whoa! That's a lot of conjecture! It's hard to draw such firm conclusions from a single data point."
'Course the Evos shouted me down and called me a fool.
Yet.
"Constantly searching for objectivity in the evolution debate..."
Hmm . . . objectivity on a evo thread. . . . nah, it'll never happen.
Fossil find prompts rethink on dinosaur feathers
Yahoo (Reuters) ^ | 3/15/2006 | Patricia Reaney
Posted on 03/15/2006 3:23:34 PM EST by The_Victor
LONDON (Reuters) - A newly discovered, perfectly preserved fossil of a 150 million-year-old dinosaur found in southern Germany may force scientists to rethink how and when feathers evolved.
The nearly complete remains of the chicken-size dinosaur named Juravenator, which is described in the journal Nature on Wednesday, were preserved in limestone. But unlike other members of the group of two-legged meat-eating predators known as coelurosaurs, it had no feathers.
"It is an absolutely new dinosaur that was not known before," said Ursula Gohlich, a palaeontologist at the University of Munich in Germany.
Remains of small dinosaurs from the Late Jurassic period are rare finds. The new fossil is nearly complete, apart from a missing part of its long tail, and shows soft tissue and an imprint of the skin but no feathers.
"Scientists had thought that all representatives of the group coelurosaurs should have feathers," Gohlich told Reuters.
"Now we have a little dinosaur that belongs to coelurosaurs that does not show feathers. This is a problem."
COMPLEX EVOLUTION
Feathers were thought to have evolved very early within coelurosaurs. All members of the group were thought to be feathered.
But Gohlich and Luis Chiappe, of the Natural History Museum of Los Angeles County in California, believe the evolution of feathers may be more complex than previously thought.
Feathers may have evolved early but then were replaced by scales in some creatures because they were not needed.
"Another possibility perhaps is that some representatives of coelurosaurs were not entirely covered with feathers, only certain areas," said Gohlich.
The newly discovered Juravenator was very young so may not have lived long enough to develop feathers. But Gohlich said that despite its age, she would have expected it to have had feathers.
"We think that feathers evolved. We have several fossils that support this theory. But our fossil asks some questions," she added.
The oldest known bird, Archaeopteryx, was also found in southern Germany. It too lived about 150 million years ago and had feathers but it is uncertain whether they were used to fly or to keep warm.
Xing Xu, of the Chinese Academy of Sciences in Beijing, said whatever the explanation, the discovery of Juravenator has enriched knowledge of early feather evolution. It could also indicate where future research could be concentrated.
"Juravenator may complicate the picture, but it makes it more complete and realistic," he said in a commentary in the journal.
The "feathers" look like a form of mold that grows on dead bodies even to this day.
Exactly. Thanks to this fossil find, we now have another piece of evidence that can be used to more exactly discern the evolutionary link between birds and their reptilian ancestors. Great article!
Ding, ding, ding! We have a winna!
Of course, we don't know how many times feathers may have evolved independently.
Some dogs know better than to eat chicken bones.
Good article... of course there are going to be people who think, "Ah Ha! Evolution is wrong!". They are of course grasping at straws.
"There's a mammal called a pangolin that has scales all over its body."
Yup, and there are several mammals that lay eggs, too. The pangolin looks something like those old extinct mammals that nobody pays much attention to.
The American Museum of Natural History has an entire room of huge, bizarre mammal fossils. It's an interesting look into the not so distant past.
And, of course, there are evolutionary cul-de-sacs too. Fitting the piece into the puzzle correctly is the key.
It is amazing the glee in some posters' eyes when scientists admit either that they made a mistake or have learned something they didn't know.
But science does not fear new data. Individual scientists may cling to pet theories, but that only lasts for a few years. When an idea is right, with the right combination of data and theory, nothing can hold it back. When mistakes are made, science figures out what went wrong, corrects the mistake, and moves on.
I think that some of those expressing the most glee are secretly both envious and afraid of science. The next new discovery could cause them to doubt a cherished belief.
If you improperly equate these two instances, they were probably right.
A fossil is a snap shot in time of a particular creature as it's body was covered in mud or silt; that being the case, one can't conclude based on a single case, if it was featherless because if had no feathers, or if it moulted before dying, or scavangers devoured the feathers after death but before the body was covered up with silt. [Caveat: if the fossil is sufficient quality that it shows skin details, I MAY be possible to deduce that the creature NEVER had feathers; just as one can tell between the skin of plucked chicken and the skin of a human, which one had feathers and which didn't.]
A foot print, on the other hand, is a foot print indicating a particular creature stepped in a particular place at some point in time. If you have evidence that based solely on the footprint and no other information, some scientist concluded the creature had to be vegetarian, feel free to post it.
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