Overview
- The University of Texas at Austin team published results Tuesday that used uranium–lead dating on shock‑recrystallized zircon crystals to assign the buried 10‑mile Ames impact structure an age of roughly 370–372 million years.
- The new radiometric age severs the crater’s link to the Ordovician Meteor Event and instead places it in the late‑Devonian Frasnian–Famennian extinction interval that removed large portions of marine life.
- Researchers relied on zircon microstructures imaged with techniques supported by NASA to identify recrystallization caused by the impact and to ensure the dated signal records the event itself rather than older, reworked fossils.
- The team argues prior fossil‑based dating using displaced conodont teeth likely produced a false Ordovician correlation because those fossils could have been mixed into younger impact deposits.
- Authors recommend applying the zircon shock‑recrystallization U–Pb method to other ancient, buried craters to improve the timing of impacts and to better test links between strikes and extinction events, a step that could change interpretations of Earth’s deep‑time crises.