A Dactyl is a large, friendly flying dinosaur found in 65,000,000 B.C. in Chrono Trigger. They live in the Dactyl Nest and are used by the humans for transportation.
When Crono's party and Ayla join forces in fighting back against the Reptites, they ride the Dactyls across the map to the Tyrano Lair.
The Dactyls are used again to flee the Lair before it's destroyed.
Having been forced back through the Time Gate in the Lair Ruins after their first visit to 12,000 B.C., Crono's party rides the Dactyls back to the Mystic Mountains.