During what era and period did the mass extinction of the dinosauers occur?

Answer 1

Mesozoic Era at the end of the Cretaceous about 65 million years ago. It was a mass extinction of some types of dinosaurs like Ornithiscians. Saurichian dinos are still alive. We call them birds.

Answer 2

Well: that would be the " Jurastic Periods yes it happend when an Astroid hit our earth about 1billion years ago where
those Dinosaurs became extincted basicly known by an Sicentist team as Palentologist in which they do their studies
with Animal Fossels also now placed in our musem for
visit http://www.la.breatarpitsmusem.com