The formation of the Rocky Mountains occurred after which era?

The $ \text{Golden Age of Fishes} $ is known as:

$A$: $Tyrannosaurus$ $rex$ had fearsome dagger-like teeth.
$R$: $Tyrannosaurus$ was the largest dinosaur depending upon herbs and shrubs.

Fish with stout and strong fins could move on land and go back to water. This occurred about ....... million years ago.

In which period is the beginning of agriculture (plant cultivation) believed to have occurred?

Which of the following were abundant in the $Mesozoic$ era?