Mesozoic Era
The Tertiary 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 Paleocene, which is the first (oldest) part of the Cenozoic Era, as the Cretaceous was the last of the Mesozoic Era.
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.
Dinosaurs dominated the Earth during the Mesozoic Era, which lasted from approximately 252 to 66 million years ago. This era is divided into three periods: the Triassic, Jurassic, and Cretaceous. Dinosaurs thrived during these periods, particularly in the Jurassic and Cretaceous, until their extinction at the end of the Cretaceous period, likely due to a combination of volcanic activity and an asteroid impact.
The question is very muddled but it can be answeredThe Cenozoic Era started with the end of the dinosaurs and is ongoing 65.5 mya to the present thereforeOf the above the following are in the Cenozoic:QuaternaryTertiaryAnd the following are out of (older than) the Cenozoic:Cretaceous
cretaceous
mesozoic
Dinosaurs lived from 231.4 million years ago to 65.5 million years ago, which falls entirely in the Mesozoic era. The Mesozoic is divided into the periods, the Triassic, Jurassic, and Cretaceous.
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.