[meteorite-list] UCLA Scientists See and Analyze 650-Million-Year-Old Fossils Inside Rocks in 3D - a First, With Implications for Finding Life on Mars
From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed Feb 1 15:48:32 2006
University of California-Los Angeles
Contact: Stuart Wolpert
January 31, 2006
UCLA Scientists See and Analyze 650-Million-Year-Old Fossils Inside Rocks
in Three Dimensions -- a First, With Implications for Finding Life on Mars
UCLA paleobiologist J. William Schopf and colleagues have produced 3-D
images of ancient fossils -- 650 million to 850 million years old --
preserved in rocks, an achievement that has never been done before.
If a future space mission to Mars brings rocks back to Earth, Schopf said
the techniques he has used, called confocal laser scanning microscopy and
Raman spectroscopy, could enable scientists to look at microscopic fossils
inside the rocks to search for signs of life, such as organic cell walls.
These techniques would not destroy the rocks.
"It's astounding to see an organically preserved, microscopic fossil
inside a rock and see these microscopic fossils in three dimensions," said
Schopf, who is also a geologist, microbiologist and organic geochemist.
"It's very difficult to get any insight about the biochemistry of
organisms that lived nearly a billion years ago, and this (confocal
microscopy and Raman spectroscopy) gives it to you. You see the cells in
the confocal microscopy, and the Raman spectroscopy gives you the
"We can look underneath the fossil, see it from the top, from the sides,
and rotate it around; we couldn't do that with any other technique, but
now we can, because of confocal laser scanning microscopy. In addition,
even though the fossils are exceedingly tiny, the images are sharp and
crisp. So, we can see how the fossils have degraded over millions of
years, and learn what are real biological features and what has been
changed over time."
His research is published in the January issue of the journal
Astrobiology, in which he reports confocal microscopy results of the
ancient fossils. (He published ancient Raman spectroscopy 3-D images of
ancient fossils in 2005 in the journal Geobiology.)
Since his first year as a Harvard graduate student in the 1960s, Schopf
had the goal of conducting chemical analysis of an individual microscopic
fossil inside a rock, but had no technique to do so, until now.
"I have wanted to do this for 40 years, but there wasn't any way to do so
before," said Schopf, the first scientist to use confocal microscopy to
study fossils embedded in such ancient rocks. He is director of UCLA's
Institute of Geophysics and Planetary Physics Center for the Study of
Evolution and the Origin of Life.
Raman spectroscopy, a technique used primarily by chemists, allows you to
see the molecular and chemical structure of ancient microorganisms in
three dimensions, revealing what the fossils are made of without
destroying the samples. Raman spectroscopy can help prove whether fossils
are biological, Schopf said. This technique involves a laser from a
microscope focused on a sample; most of the laser light is scattered, but
a small part gets absorbed by the fossil.
Schopf is the first scientist to use this technique to analyze ancient
microscopic fossils. He discovered that the composition of the fossils
changed; nitrogen, oxygen and sulfur were removed, leaving carbon and
Confocal microscopy uses a focused laser beam to make the organic walls of
the fossils fluoresce, allowing them to be viewed in three dimensions. The
technique, first used by biologists to study the inner workings of living
cells, is new to geology.
The ancient microorganisms are "pond scum," among the earliest life, much
too small to be seen with the naked eye.
Schopf's UCLA co-authors include geology graduate students Abhishek
Tripathi and Andrew Czaja, and senior scientist Anatoliy Kudryavtsev. The
research is funded by NASA.
Schopf is editor of "Earth's Earliest Biosphere" and "The Proterozoic
Biosphere: A Multidisciplinary Study," companion books that provide the
most comprehensive knowledge of more than 4 billion years of the earth's
history, from the formation of the solar system 4.6 billion years ago to
events half-a-billion years ago.
A 650-million-year-old fossil from Kazakhstan. Top: optical image of
fossil cyanobacterium. Middle: confocal optical image of the same fossil.
Bottom L: close-up of section of confocal optical image. Bottom R: Raman
chemical image of same boxed region.
Credit: Dr. J. William Schopf/UCLA
Received on Wed 01 Feb 2006 02:53:53 PM PST