Jurassic

The Jurassic was a period in early Earth history in which the dinosaurs thrived.

A Concorde designated Golf Victor Foxtrot mysteriously disappeared from Heathrow Airport in 1982, inadvertently travelling down a time corridor to the Jurassic period. The Fifth Doctor used a second Concorde, designation Golf Alpha Charlie, to investigate the first Concorde's disappearance and followed it through the time corridor. At one point The Master's TARDIS was temporarily disguised as Concorde Golf Victor Foxtrot, and materialised around it. Eventually, Concorde Golf Alpha Charlie was repaired using parts taken from Concorde Golf Victor Foxtrot and returned to 1982, leaving Concorde Golf Victor Foxtrot buried in the past. By 1982 Concorde Golf Victor Foxtrot was fossilised and buried beneath Heathrow. (DW: Time-Flight)

When the Seventh Doctor and Ace encountered dinosaurs after landing on Earth, the Doctor believed they had landed in the Jurassic period, but had infact arrived in an alternate timeline where Silurians ruled over humanity. (NA: Blood Heat)

Professor Saurian tried to change Earth history using a 'roll-back machine' that saw New York being evacuated as the city was overrun by dinosaurs from the Jurassic. the Doctor defeated Saurian this time by resetting his machine via "reversing the polarity of the neutron flow". Saurian was taken along with his machine and the dinosaurs back to the Jurassic Age. (DWA: Dinosaurs in New York!)