Ummm, there are people
who haven't yet gotten past
Galileo's schtick . . .
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."
"More retroactive confessions of problems in the postulations of evolutionary history, and another overturning of currently-held beliefs."
Only in your imagination. This was expected by evolutionary theory. It is support for the theory as it was before the find.
You say that like you think that's a bad thing. This is how science is done -- we come up with the best explanation for the available facts, and adjust the explanation as new facts come in. Newton's theories aren't wrong, but they do break down on the quantum scale. When they had to rewrite science textbooks to append an asterisk to Newton, that wasn't a failure of science, and neither is this discovery.
You say that like you think that's a bad thing. This is how science is done -- we come up with the best explanation for the available facts, and adjust the explanation as new facts come in. Newton's laws aren't wrong, but they do break down on the quantum scale. When they had to rewrite science textbooks to append an asterisk to Newton, that wasn't a failure of science, and neither is this discovery.
"Most textbooks in school (math, economics, literature etc.) come out with new versions every year just so they can keep making money and not allow students to leech off of used copies. Science textbooks have to do so to account for new changes."
Wholly irrelevent to the article. Care to try again?
"designed to fit a theory that so far has been unprovable!"
You mean like creation?
intrep
"Science textbooks have to do so to account for new changes."
Maybe they should keep tham all the same. That way Galileo would still be a criminal.
Ummm, there are people
who haven't yet gotten past
Galileo's schtick . . .
ALERT!! The latest copy of MAD magazine is on the newsstands... I'm outa here!!
Thank you for that work of genius.
That is one of those things I'd really rather not know...
More anti-science ranting.
Sort of like some preachers (read most of them) will convince their congregations to drink Kook-Aid laced with cyanide.
"and another overturning of currently-held beliefs."
In the Middle East they call currently-held beliefs Islam. They don't allow science in their countries. They wipe themselves with their bare left hand too. Ahh, but only we were a religious state.
Well there's this (if you suscribe):
"Shells may represent oldest known beads" - puts Joe the Beadman at 100,000-135,000 years ago in Israel. Definitely pre-Eden. Can't even complain the flood was local.
ScienceNews 7/8/2006, page 30.
"puts Joe the Beadman at 100,000-135,000 years ago in Israel."
Legend has it, Joe was really from the Tigris area. He had packed those beads with salt peter, and did the smithereen thing in present day Jeruselum. He never knew why he had the urge to do that...
Most articles mention 530 mya.
The Burgess shale is the accumulated silt from a reef that runs some 13 miles under four mountains.
I don't think anyone could factually say that the entire layer is 530 (or 505) million years old.
Age is less important than era here. If these fossils were found in the Burgess, they cannot be Pre-Cambrian, since the Burgess has been placed in the Middle Cambrian - but the date given (560 million years old) IS Pre-Cambrian.
So something is wrong here.
Abstract from a recent lecture:
“The Burgess Shale animal Odontogriphus and the ancient origin of squids, snails, clams and other mollusks”, Jean-Bernard Caron*, David Rudkin Department of Natural History-Palaeobiology, Royal Ontario Museum, Amélie Scheltema Woods Hole Oceanographic Institution, Woods Hole, Massachusetts and Christoffer Schander, University of Bergen, Department of Biology (IFM)Molluscs, including the familiar squids, snails and clams, represent one of the most diverse groups of animals living today, with possibly more than 200,000 extant species. Most molluscs possess a mineralized shell that is readily preserved after the death of the animal, and these remains are found in fossil deposits worldwide. The oldest molluscan shells are known from rocks dated at about 540 million years, marking the time when many different groups of organisms first evolved the ability to secrete hard shelly parts. This rapid appearance of a diversity of animals in the fossil record has been called the “Cambrian explosion.”
In this study we propose that the strange and entirely soft-bodied fossil animal Odontogriphus omalus, from the 505 million-year-old Burgess Shale, represents an ancestral mollusc possibly sharing a common ancestor with all known shelly molluscs. Our redescription and reinterpretation of Odontogriphus is based on 189 new specimens from the Burgess Shale collections of the Royal Ontario Museum.
From Berkeley:
"The Burgess Shale contains the best record we have of Cambrian animal fossils. The locality reveals the presence of creatures originating from the Cambrian explosion, an evolutionary burst of animal origins dating 545 to 525 million years ago."
(http://www.ucmp.berkeley.edu/cambrian/burgess.html)
So...which is it?
Are the fossils of the Burgess Shale in or out of the Cambrian period?
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