Posted on 07/13/2006 6:12:42 AM PDT by doc30
Mollusk fossils push back evolution, ROM scientists say
Life 560 million years ago more advanced than previously believed, article says.
Two Canadian paleontologists have discovered dozens of fossils of a soft-bodied, deep-sea dweller that lived more than half a billion years ago, adding one more piece to the enigmatic puzzle that is the history of life on Earth.
The 189 well-preserved fossil specimens of Odontogriphus omalus have been interpreted as the world's oldest known soft-bodied mollusk, and were found in British Columbia's mountains in the Burgess Shale, one of the most important fossil sites in the world.
The newly discovered fossils are remarkable, one of the researchers notes, because there are perfect impressions of all of the animal's soft tissues.
The fossils show the early mollusk had an oval body ranging in size from a few millimetres to 20 centimetres with simple gill-like structures surrounding a muscular sole or "foot" on the underside.
The stomach, intestines, outer membrane and mouth are all visible.
This discovery pushes back the history of animal evolution tens of millions of years to 560 million years ago in Precambrian time (543 million years ago and earlier), according to the Royal Ontario Museum's David Rudkin, co-author of the article published in today's issue of the journal Nature.
Very few fossil specimens have been found from that time period. The Cambrian Period (543 million to 490 million years ago) marked the sudden appearance of complex multicellular macroscopic organisms.
In the Precambrian era, before the so-called explosion, organisms were thought to be much simpler, but this study shows that was not the case.
"This is a crucial interval in evolutionary history because it seems to represent a time in which a great deal happened," he said.
"Odontogriphus seems to be a late holdover that somehow got preserved in with the creatures from the Cambrian . . . opening up new windows on evolution for us," Mr. Rudkin said.
The specimens were collected over 15 years in the late 1980s and 1990s by the ROM and, upon closer examination, were found to have distinguishing "molluskan" features including a specialized feeding structure called a radula, made up of short rows of small, tooth-like elements that would wave and sweep food into the mouth.
The shell-less mollusks grazed on seafloor bacterial growths.
Odontogriphus, which translates to "toothed riddle" was originally discovered in 1976 from a single, poorly preserved specimen. Until now, it has been described as an "enigmatic organism," according to the study's lead author, Jean-Bernard Caron, also of the ROM.
"Our study redescribes and reinterprets previously unrecognized features that link Odontogriphus to the mollusks, one of the most diverse and important groups of animals living today," Dr. Caron said.
Odontogriphus predates modern-day mollusks -- with 200,000 living species today including snails, clams, squids and octopuses -- which began to develop hard shells during the Cambrian Period to survive.
"They were the last of their kind and they were dying out because the sea floor was changing and all these other animals started developing hard parts and new strategies for dealing with predators," Mr. Rudkin said. "The successful mollusks are those that branched off and developed shells."
Mr. Rudkin said the fact that many mollusks have survived such a catastrophic extinction could shed light on the evolutionary path many animals may take.
"Those lessons we learn from the past -- about where groups of organisms originated, when they become extinct, how they became extinct, or if they didn't become extinct entirely, how they recovered from extinction -- we use that kind of historical background to help us predict what might happen in modern extinction circumstances. Maybe there's a lesson in there for us."
What it really shows is that scientist will do anything to try to disprove the Cambrian explosion, they have been trying for years. I will wait until all the facts are in, the dating of these fosils may be off a tad, because some scientist(read most all of them) will fake, cheat, lie, steal and falsify findings in order to prove a theory.
That all fossils before the Cambrian were "soft" bodied is an old theory and unprovable, as so many postulations from evos are. It was put forth in order to "explain" the Cambrian and scientists have been looking for proof for many years, and now, suddenly, someone finds a "soft" body creature, a complicated one, that supposedly dates before the Cambrian, and all of you die hards jump on it as if there has never been a dating error made, or facts lied about, in the history of evolutionary theory.
Don't cry to hard if this proves to be just another fake, designed to fit a theory that so far has been unprovable!
You sure sound like a creationist, with all the usual anti-science jargon. You have the creationist talking points down pretty well too.
Exactly so. The "explosion" started earlier and lasted longer than the first returns on the fossil record indicated. (That is, it was not really an "explosion" at all.) Poorly fossilizing soft bodies hid much of the story from us by leaving a very scanty record, but there were exceptions. This is one of them coming to light. There have been others. Soft-bodied precursors to trilobites come to mind.
Interestingly, creationists mock all such "deep diverge" explanations of the Cambrian with, "Were you there? Oh, sure! Show me the fossils!" etc. Well, this is one.
There's no spinning it. If we had known this already, it wouldn't be news.
The existence of news in science is proof that science is wrong.
The purest form of creationism is to go through the whole Voodoo dance of evidence denial, accusations of centuries-old scientific conspiracies, claims of atheistic motivations, ad hominem attacks, etc., and then -- the ultimate! -- to deny being a creationist, but instead to claim being a humble, open-minded, truly scientific seeker of truth.
We just found a Precambrian soft-bodied mollusc and you're dismissing it with this arm-waving rant?
I think I've heard that Ed Asner isn't a communist. He's just a decent American who wants a sane foreign policy vis-a-vis Cuba, so we shouldn't dismiss him out of hand.
Great find Doc. Eventually the Cambrian Explosion is going to found to be nothing more than a puff. It looks like that now because there wasn't much to fossilize in pre-Cambrian animals. With time we will find the diversity in the late Pre-Cambrian was quite high.
ROM scientists are
very fixed in their viewpoints.
RAM scientists can
be more flexible.
Start with what the ROM guys say,
then work with RAM guys . . .
A few minutes on Google shows that pre-Cambrian fossils of complex multi-cellulars, while rare, are not unheard of.
Something is not right here. The article says the organisms were 560 million years old - or basically late Precambrian. But the Burgess is Middle Cambrian (505 million years old).
What's with this assertion of trying to disprove the Cambrian Explosion? It's a scientist's job to disprove things. And if you are waiting for all the facts to come in, you are going to be waiting a long, long time. Facts are constantly coming in, each with a different degree of impact.
If you are looking for constant, unchanging understanding of how the natural world works, you will not find it because there are always new facts and new discoveries happening in science.
That all fossils before the Cambrian were "soft" bodied is an old theory and unprovable, as so many postulations from evos are.
Well, it wasn't ONE fossil that was found and hyped, it was 189 separate fossils. And the youngest predates the Cambrian explosion by 17 milion years. The others are even older. That is clear, irrefutable evidence that, up to now, has been suspected according to evolution, but not demonstrated until now. This is just another example of a hypothesis in Evolution (soft bodied creatures predating more easily preserved hard bodied creatures), being tested and confirmed through the observation of new facts. This is science at its finest!
Ooops! Sorry.
Somethings are worth repeating. :)
I believe you
(Now you top that one)
You sure sound like a creationist, with all the usual anti-science jargon. You have the creationist talking points down pretty well too.
For starters, stay clear of psychology, anthropology and biology (especially botany).
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