Nature & science

An evolutionary explosion captured in rocks

DMNS scientists joins team studying in the Grand Canyon

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Just like we all use a calendar to mark time and the important events in our lives, scientists use one that stretches back millions and millions of years. But while the daily calendar we use is fixed, the ones scientists use isn’t.

“To be able to determine cause and effect of events, we need to locate things in their place and time,” said James Hagadorn, Denver Museum of Nature & Science’s curator of geology. “We’re always fine-tuning, and know there’s more fine-tuning to go.”

That scientific calendar will be getting more precise thanks to a new research project happening in the Grand Canyon to study sedimentary rock layers from the Cambrian Period. The project will feature a team of scientists from the museum, including Hagadorn; Boise State University; the University of New Mexico; Utah State University; the University of Calgary; and the University of Chicago. The project received a three-year, $815,000 grant from the National Science Foundation’s Sedimentary Geology and Paleobiology program.

According to information provided by the museum, part of the project will be “to find new occurrences of fossils like trilobites, brachiopods and microfossils, to measure how ocean chemistry changed in lockstep with fossil extinctions, and to apply new techniques for precise dating of rock layers to figure out how fast this all happened.”

As a geologist and paleontologist by training, this is exactly the kind of work a “detective in deep time” like Hagadorn lives for. Rather than use traces like DNA and fingerprints, he makes use of isotopes and structures in rocks to determine what happened at different moments in Earth’s history.

“We can’t time travel back to the moment to know what happened, but we can reconstruct the moment with some of the clues we find,” he said. “The dating of the rocks in the Grand Canyon doesn’t just affect those rocks — the whole Cambrian dating system changes. As a result, the work in the Grand Canyon changes the whole geologic calendar we use.”

The Cambrian Period - also known as the “Cambrian explosion of life” - was when many animals first burst on the scene. As Hagadorn explains it, the life up to this point was generally small, slimy and had no backbone. The Cambrian period is when life starts to biomineralize and build-up skeletons — it’s when animals start eating each other, competing against each other and burrowing into the land. With so many evolutionary events happening so close together, learning more about the when, how and why could be profoundly important.

Which is what is inspiring Hagadorn and the rest of the scientists to tackle this giant, millions-year-old puzzle. Not only will it provide glimpses into the past, it will inform our present and future.

“The work we’re doing is standing on the shoulders of our predecessors, and 20 years from now, some young punk is going to wonder at how we did things. It’s part of process,” Hagadorn said. “We want to create informed citizens of the planet. We all have the power to care, and that translates in the ability to do.”

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