What a lot of people are not aware of either is that the K-T extinction did not "start" at the impact. Life, particularly marine life, had already started dying off millions of years leading up to the K-T impact event, likely resulting volcanic extrusion of the Deccan Traps. It appears that the K-T impact may have been the straw that broke the camel's back.
In addition, though I do not know if there have been others identified in the stratigraphic record (possibly Upheaval Dome in Utah), the Alamo Breccia in Nevada is evidence of an impact that was discovered to be
within the Guilmette Limestone formation. The meteor impacted in what is now southern Nevada, a marine coastline at the time. Despite what Creationists want to believe, geologists can tell the difference between shallow water and deeper water depositional environments.
You can read about it here:
Alamo Megabreccia: Record of a Late Devonian Impact in Southern Nevada
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