Deep under the small town of Ames, Oklahoma, lies a crater about 10 miles (16 kilometers) wide, left by a space rock and long since buried under layers of sediment. For decades, scientists thought it formed around 467.5 million years ago. A new study says that date was off by nearly 100 million years.
Geologists at the University of Texas at Austin now put the impact at roughly 370 million years ago, during the Late Devonian period. The findings appear in the journal Meteoritics & Planetary Science.
How the old date went wrong
The earlier estimate relied on fossils: the tooth-like remains of conodonts, ancient eel-like animals from the Ordovician period. But an impact churns up whatever rock is already there. The researchers think those fossils were older material that the collision mixed into the crater, not a timestamp of the impact itself.
So the team turned to zircon, a tough mineral that can be dated using the slow decay of uranium into lead. They also used NASA imaging techniques to confirm that the zircon crystals had been altered by the impact.
“No matter what technique we used, it was coming back to this younger signal,” said lead author Elizabeth Catlos, an associate professor at UT Austin.
Why the new date matters
The old age linked Ames to the so-called Ordovician Meteor Event, a cluster of impacts across North America that some researchers have suggested could hint at Earth once having a ring of asteroid debris. Moving Ames out of that group weakens that pattern.
Instead, the new date lands close to the Frasnian-Famennian extinction about 372 million years ago, a major die-off of marine life. The study doesn’t claim the Ames impact caused it, but the timing is notable.
The crater also has practical value: it is a significant oil and gas producer, a reminder that buried impact structures can trap valuable resources in shattered rock.
The catch
The crater is buried, so it can’t be studied as directly as an exposed crater. And the link to the extinction is about timing, not proven cause and effect — any connection would need much more evidence.
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