Geologists refine the timing of the Cambrian explosion of diversity of life using Grand Canyon rock layers

DENVER―May 7―The history of the Earth and of life on Earth is written in sedimentary rock layers. Sedimentary rock layers 541- 485 million years old, from the Cambrian Period, provide a record of incredible mystery. And, thanks to recent findings, a more exacting timeline.

A new research project, with investigators from Boise State University, The University of New Mexico, Utah State University, the University of Calgary, the University of Chicago and the Denver Museum of Nature & Science, has been funded with a three-year, $815,000 grant by the National Science Foundation’s Sedimentary Geology and Paleobiology program.

This team of scientists, including Denver Museum of Nature & Science Curator of Geology James Hagadorn, is undertaking a detailed study to find new occurrences of fossils such as 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.

Hagadorn is coordinating a team of paleontologists to study the fossils.

“The timing, causes and impacts of this debut of animal life, known as the Cambrian “explosion,” are poorly understood,” said Hagadorn. “Yet fossil clues to understanding this event are entombed in Cambrian strata that formed as oceans flooded the world’s continents, and as coastal environments blanketed the landscape with vast swaths of sand, mud, and fossils.”

This explosion in the diversity of multicellular animal life occurred very rapidly during the Cambrian Period, as did major continental flooding events. But exactly when and how fast it happened, is a challenge to decipher. That’s because over the millennia, the rock layers that record these events have become separated as continents broke up, and been distorted as mountain ranges have risen in their place. Thus, the sedimentary layers that contain clues about these Cambrian events need to be virtually connected back together, like piecing back together an overturned puzzle.

To tie these pieces of the Cambrian story back together, the team will date fossil-bearing strata from across the American West, so they can suture the fragments of this evolutionary and tectonic story back together. Boise State University Professor Mark Schmitz is the project lead and will spearhead dating the strata by measuring the radioactive decay that occurs in tiny crystals hidden in these rocks.

About the Denver Museum of Nature & Science

The Denver Museum of Nature & Science is the Rocky Mountain Region’s leading resource for informal science education. Our mission is to be a catalyst and ignite the community’s passion for nature and science. The Museum offers a wide variety of engaging exhibitions, programs, activities and scientific research to inspire public appreciation and understanding of the wonders of Colorado, Earth and the universe. The Museum is located at 2001 Colorado Blvd., Denver, CO, 80205. Information: or 303.370.6000. Many of the Museum’s educational programs and exhibits are made possible in part by the citizens of the seven-county metro area through the Scientific & Cultural Facilities District. The Museum is accredited by the American Alliance of Museums. Connect with the Museum on Facebook, Twitter, and Instagram.



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