Ceratopsians and Hardosaurs were some of the largest terrestrial fauna
at the K-T boundary. Their food requirements would almost certainly
preclude survival in a devastated ecology. Above a specific size/weight
threshold, there apparently were no survivors.
James
John Schneiderman wrote:
Maybe answer a few questions like, why the environmentally delicate
amphibians faired better than dinosaurs like ceratopsians and hadrosaurians?