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.
From the article:
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.Removed feathers would have left a noticeable "chicken skin" imprint, I think. Still, too many viable scenarios to draw any detailed conclusions just yet.
Based solely on the footprints they determined that the dinosaur was a meat-eater.
http://www.freerepublic.com/focus/f-news/1504547/posts
The answer is simple - it got plucked before it died. Maybe Space Aliens, maybe Noah was hungry. The possibilities are endless.
Maybe an even better point. Those monotremes are in the mammal group but their line branched off on its own way back there.
What we're doing is learning more about the early history of the coelurosaur taxon. More data points should help to tell a more coherent story.
There are no problems in science, only opportunities.
I think this is fascinating. If this isn't some aberration, it means that there were closely related species, some with feathers, some without.
One possibility is that feathers evolved more than once. I think this is highly likely. This means it should be possible to find different genes for feathers from widely divergent modern bird species. Unless of course, the line went extinct.
Every dispute, unexpected result, and unanswered question is proof that science is a house of cards about to fall. Except it never does, of course.
Reality does not impinge upon people who pin their hopes on such phantoms.
Something a lot of people fail to take into account. Most fossil finds are "branches" off any main line connecting one species to another. Extinction plays a huge role in evolution & the formation of the fossil record that we observe.
Yep, I still can't figure out why humans don't have nice full coats of body hair. After all, aren't we the cream of the evolutionary crop? Why evolve to have to wear clothes?
so when new evidence tells you the overall theory may be
incorrect, you just make the theory more complicated to explain all the variations? Kinda like Ptolemy, no?
Just compare ichthyosaurs to modern whales. Many similar traits in distinctly different lineage of species.
The Smithsonian has a bunch too. I especially like the glyptodons, huge armadillos that may have been hunted to extinction because people used their shells as **shelters**.
And if you want to know why we seem to be evolving away from that (ew!), just ask yourself if you would want to mate with anything with that much hair.
*shudder*
The monotremes are an excellent thing to mention in discussions of mammalian evolution. Australia got isolated at the perfect time to evolve a whole series of wierd mammals, unlike those anywhere else on the planet.
Marsupials, monotremes, and others. The Opossum is about the only marsupial anywhere outside of Australia. No monotremes exist except in Australia and the surrounding islands.
It's a perfect study of mammalian evolution. Every type of animal, from big herbivores to carnivorous predators evolved there, and in a unique way. The isolation is what did it.
It's inexplicable, except through evolution.
So far, and this is documented, no feathers have been found on any dino fossils, regardless of the claims. They have all been proven to be false and not feathers. However, evos continue to chant the feathers on dinos mantra. They are like Dems, they will believe what they want and to hell with the trurh, the feather hoax continues. I am NOT a christian, NOT a creationist or IDer, just a guy who wants the truth to be told. If evolution is real, then their is no need for fakes and false claims, although they continue unabated and with no shame from the evos!
I meant to include you in the To: list on post 54
Yes, the glyptodons. What an interesting group of mammals!
Because all dinosaurs found with that foot-shape previously (and there have been many of them) have been determined to be meat-eaters by other evidence, such as jaw-construction and body designed for predation.
It isn't definite, but the inference is strong.
So, the feather imprints on the archeopteryx fossils aren't feathers?
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