First time ancient fossils seen in 3-D
By Stuart Wolpert
UCLA Today
Since his first year as a Harvard graduate student in the 1960s, UCLA paleobiologist J. William Schopf had wanted to analyze the chemistry of an individual microscopic fossil inside a rock. But the tools didn’t exist to do that.
Some 40 years later, Schopf has become the first person to accomplish this goal using advanced techniques of confocal laser scanning microscopy and Raman spectroscopy. Schopf and his colleagues have produced three-dimensional images of ancient fossils — 650 million to 850 million years old — preserved in rocks, an achievement that has never been done before.
“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. He directs UCLA’s IGPP Center for the Study of Evolution and the Origin of Life.
“It’s very difficult to get any insight about the biochemistry of organisms that lived nearly a billion years ago, and this 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,” Schopf said. “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, which was funded by NASA, has some broad implications that reach far beyond the study of ancient fossils on Earth.
If a future space mission to Mars brings rocks back to Earth, Schopf said the techniques he has used could enable scientists to look at microscopic fossils inside the rocks and search for signs of life, such as organic cell walls. These techniques would not destroy the rocks.
His research is published in the January issue of the journal Astrobiology. Schopf’s UCLA co-authors include geology graduate students Abhishek Tripathi and Andrew Czaja, and senior scientist Anatoliy Kudryavtsev. (Schopf published ancient Raman spectroscopy three-dimensional images of ancient fossils last year in the journal Geobiology.)
Raman spectroscopy, a technique used primarily by chemists, allows you to see the molecular and chemical structure of ancient micro-organisms in three dimensions, revealing what the fossils are made of without destroying the samples.
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. |
