Planetary impacts. Did the mammoth slayer leave a diamond calling card?
Kerr
Richard A
RA
D000818:Animals; D018130:Diamond; D053476:Extinction, Biological; D019015:Geologic Sediments; D019110:Meteoroids; D017348:Microscopy, Electron, Scanning Transmission; D049329:Nanostructures; D009656:North America; D013995:Time
D018130:Diamond