Dinosaurs lived during the Mesozoic era, between 250 and 65 million years ago. The earliest discovered dinosaur species, Nyasasaurus parringtoni, dates from 245 million years ago. Dinosaur fossils are most common between rock strata that are 225 to 65 million years old.
The latest dinosaur fossils found as of 2014 date from strata that is 65 million years old, just before the K-T boundary. The K-T boundary is a geological feature caused by a massive asteroid impact throwing large amounts of debris into the atmosphere. As of 2014, no dinosaur fossil has been found above the K-T stratum, which coincides with the end of the Mesozoic era.