| Answer | Crossword Clue |
|---|---|
| JURASSIC | Period when birds and mammals appeared |
| TRIASSIC | Period when mammals first appeared |
| jurassic | noting or pertaining to a period of the Mesozoic Epoch, occurring from 190 to 140 million years ago and characterized by an abundance of dinosaurs and the advent of birds and mammals |
| JURASSIC | Period in which the earliest birds appeared |
| MIOCENE | When mammals appeared |
| EOCENE | Epoch when mammals appeared |
| EOCENE | Epoch when modern mammals appeared |
