Researchers at The University of Texas at Austin have substantially revised a key chapter of Oklahoma’s geologic history, a discovery that could fundamentally alter how scientists interpret major evolutionary and extinction events in the history of life on Earth.
Deep beneath the surface of the town of Ames, Oklahoma, lies a massive meteor impact structure that stretches for miles underground. Although thick layers of modern sediment now entirely obscure the crater from view, it remains a site of immense scientific curiosity and tremendous economic significance. Beyond its geological value, the Ames impact structure is a prolific regional producer of oil and natural gas, tying the subterranean remnants of an ancient cosmic collision directly to modern energy industries.
A Crater Long Linked to an Ancient Meteor Event
For decades, the mainstream scientific consensus placed the formation of the Ames crater firmly within a specific chapter of North American geology. Researchers long believed the crater belonged to a dense cluster of major meteor impacts scattered across the continent, all dating to roughly 467.5 million years ago. That extensive period of extraterrestrial bombardment is widely known to geologists as the Ordovician Meteor Event.
Because so many distinct impact structures across North America appear to share this exact same timeframe, some researchers have previously proposed a dramatic hypothesis: that Earth may have once been surrounded by a Saturn-like ring of dense asteroid debris during the Middle Ordovician epoch. Such a ring would have continually shed large fragments down onto the planet’s surface over an extended period.
However, groundbreaking new work from a team of researchers at The University of Texas at Austin has conclusively shown that the Ames impact does not belong to that ancient episode at all.
By meticulously dating microscopic zircon crystals extracted from granite that had been intensely altered by the shock of the impact, the research team determined that the meteorite actually struck our planet approximately 370 million years ago, during the Late Devonian period. That stunning revelation makes the Oklahoma crater nearly 100 million years younger than previously believed, severing its ties to the Ordovician period entirely.
"No matter what technique we used, it was coming back to this younger signal," said lead author Elizabeth Catlos, an associate professor in UT’s Department of Earth and Planetary Sciences.
The meticulous research detailing these findings was published in July in the scientific journal Meteoritics & Planetary Science.
Why the Earlier Date Was Misleading
To understand how the scientific community operated under a miscalculation for so many years, researchers had to examine how the crater was originally dated. Before this new study, the Ames impact had only ever been dated using biological evidence rather than absolute radiometric dating of the rocks themselves.
In previous decades, researchers had discovered fossilized teeth belonging to an ancient, eel-like marine animal known as a conodont, which were remarkably preserved within the impacted rock layers. Because those specific fossils came from organisms that lived during the older Ordovician period, geologists naturally assumed the impact that trapped them must have occurred at the same time.
But Catlos explained that the fossilized teeth were likely already millions of years old by the time the asteroid actually struck the region. The violent energy of the meteor impact likely churned up vast amounts of older, preexisting material from the surrounding landscape and mixed those ancient fossils directly into the newly forming impact breccia, all while miraculously preserving their delicate physical structures.
The modern application of zircon dating provides a starkly different, highly precise timeline. It demonstrates definitively that the Ames crater could not have formed during the Ordovician Meteor Event.
Instead, its newly established age places its formation uncomfortably close to the Frasnian-Famennian mass extinction event. That catastrophic ecological collapse occurred roughly 372 million years ago and wiped out a staggering proportion of all marine life on Earth, fundamentally reshaping the trajectory of biological evolution.
Tiny Zircon Crystals Preserve the Impact
Danny Stockli, dean of the Jackson School of Geosciences and a co-author of the study, emphasized that uranium-lead (U-Pb) dating of zircon crystals offers one of the most reliable and accurate ways to determine when cataclysmic events occurred deep within Earth’s distant past.
Beyond merely providing a numeric age, remarkably resilient zircon crystals are also capable of preserving microscopic structural deformations created by the unimaginable, crushing pressures generated during a high-velocity meteor impact.
"These small crystals allow us to go back in time and learn about the major changes to Earth’s ancient landscapes," Stockli said. "It would be great to do this for more of the meteor impact sites across the continent so we could get a more accurate timeline for these major events."
To confirm beyond a shadow of a doubt that the extracted zircons had indeed been physically altered by the heat and shock of a meteor strike, the research team collaborated with NASA. Scientists utilized advanced imaging techniques, specifically cathodoluminescence and electron backscatter diffraction, to peer inside the microscopic crystals.
When a robust mineral like zircon experiences the extreme thermodynamic conditions of a hypervelocity impact, it undergoes a distinctive form of recrystallization. Those minute structural changes can be clearly detected with NASA’s specialized imaging technology, allowing the researchers to scientifically verify that the mineral grains had indeed recorded the violent signature of the cosmic collision itself.
A New Piece of a Mass Extinction Puzzle
According to Catlos, establishing much more precise dates for mass extinctions and other profound geological milestones is an absolute necessity for understanding the complex mechanisms of planetary change over vast expanses of time.
One of the most persistent and fiercely debated questions in Earth sciences is whether major biological extinction events were triggered primarily by external forces from space, such as massive asteroid and meteor impacts, or by internal terrestrial processes, including cataclysmic episodes of prolonged volcanic activity that altered the atmosphere and oceans.
"With this research, we’re basically taking a major pawn out of the Ordovician Meteor Event and dumping it into the Frasnian-Famennian event, and saying, ‘This is where this impact belongs,’" Catlos said.
The ambitious research project was originally initiated by Andrew Parisi, a former graduate student at the Jackson School of Geosciences who graduated in 2018 and has since passed away. During his studies, Parisi traveled directly to Oklahoma to secure the Ames rock core samples from the Oklahoma Geological Survey. He then extracted the fragile zircon crystals from the dense material and began the painstaking work of helping determine their true geological ages.
Additionally, co-author Michael Brookfield, an affiliated researcher at the school, also passed away before the final manuscript could be published.
Other key contributors to the published research include Research Professor Sean Gulick and Professor Emeritus Mark Cloos, both from the Jackson School of Geosciences at The University of Texas at Austin.