Mesozoic Era
Cenozoic
Triceratops existed from 68 to 65.5 million years ago. That was at the end of the Maastrichtian stage, the last stage of the Cretaceous period, which was the last period of the Mesozoic. In fact, Triceratops existed at the very end of the Mesozoic era and was one of the dinosaurs wiped out by the K-T extinction.
The period after the Cretaceous is the Paleogene period, which is part of the Cenozoic era. It includes the Paleocene, Eocene, and Oligocene epochs.
It is the final period of the Mesozoic era.
The dinosaurs lived in the Mesozoic Era, which includes the Triassic, Jurassic, and Cretaceous periods. The first dinosaurs appeared in the late Triassic and went extinct at the end of the Cretaceous.
It was part of the Mesozoic Era.
The dinosaurs died out 65.5 million years ago. That was the very end of the Maastrichtian stage, which was the last stage of the Cretaceous time period. The Cretaceous was the last period of the Mesozoic era.
Cretaceous period
mesozoic
The Paleocene, which is the first (oldest) part of the Cenozoic Era, as the Cretaceous was the last of the Mesozoic Era.
The Cretaceous / Tertiary boundary (KT) occurred 65 million years ago and extinctions of most dinosaurs was probably due to a meteorite impact in the Yucutan peninsular of Mexico known as the Chixulub crater.
Statistical analysis of the fossil records indicates that somewhere around 35% of all species disappeared at the end of the Cretaceous Era (there is considerable margin for error in that figure).
There were three periods in the Mesozoic Era. The Triassic Period, the Jurassic period & the Cretaceous Period.