Original: The entire class of Conodonts , or at least what was left of them at the time , are postulated to have been wiped out by the Triassicâ '' Jurassic extinction event , which occurred roughly 200 million years ago .
Simplified: The entire class of Conodonts , or at least what was left of them at the time , were wiped out by the Triassicâ '' Jurassic extinction event , which occurred roughly 200 million years ago .