Inside rocks, implications for finding life on Mars

January 31, 2006

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 chemistry.

"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 hydrogen.

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.
-end-


University of California - Los Angeles

Related Fossils Articles from Brightsurf:

First exhaustive review of fossils recovered from Iberian archaeological sites
The Iberian Peninsula has one of the richest paleontological records in Western Europe.

Fossils reveal mammals mingled in age of dinosaurs
A cluster of ancient mammal fossils discovered in western Montana reveal that mammals were social earlier than previously believed, a new study finds.

Oldest monkey fossils outside of Africa found
Three fossils found in a lignite mine in southeastern Yunan Province, China, are about 6.4 million years old, indicate monkeys existed in Asia at the same time as apes, and are probably the ancestors of some of the modern monkeys in the area, according to an international team of researchers.

Scientists prove bird ovary tissue can be preserved in fossils
A research team led by Dr. Alida Bailleul from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences has proved that remnants of bird ovaries can be preserved in the fossil record.

Biosignatures may reveal a wealth of new data locked inside old fossils
Step aside, skeletons -- a new world of biochemical ''signatures'' found in all kinds of ancient fossils is revealing itself to paleontologists, providing a new avenue for insights into major evolutionary questions.

Fish fossils become buried treasure
Rare metals crucial to green industries turn out to have a surprising origin.

New Argentine fossils uncover history of celebrated conifer group
Newly unearthed, surprisingly well-preserved conifer fossils from Patagonia, Argentina, show that an endangered and celebrated group of tropical West Pacific trees has roots in the ancient supercontinent that once comprised Australia, Antarctica and South America, according to an international team of researchers.

Ancestor of all animals identified in Australian fossils
A team led by UC Riverside geologists has discovered the first ancestor on the family tree that contains most animals today, including humans.

Metabolic fossils from the origin of life
Since the origin of life, metabolic networks provide cells with nutrition and energy.

Fossils of the future to mostly consist of humans, domestic animals
In a co-authored paper published online in the journal Anthropocene, University of Illinois at Chicago paleontologist Roy Plotnick argues that the fossil record of mammals will provide a clear signal of the Anthropocene era.

Read More: Fossils News and Fossils Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.