Brachychampsa
The genus first appeared during the late Campanian stage of the Late Cretaceous ( Judithian North American stage ) and became extinct during the early Danian stage of the Paleocene ( Puercan North American stage ) , a few million years after the Cretaceous–Paleogene extinction event . 
<triplet> Campanian <subj> Late Cretaceous <obj> part of <triplet> Late Cretaceous <subj> Campanian <obj> has part <subj> Paleocene <obj> followed by <triplet> Danian <subj> Paleocene <obj> part of <subj> Cretaceous–Paleogene extinction event <obj> follows <triplet> Paleocene <subj> Danian <obj> has part