In the Middle Triassic, the first primitive dinosaurs appear, small and swift bipedal reptiles.
A large-scale extinction wave removes many competing reptile species, allowing dinosaurs to become the dominant land animals.
Enormous herbivorous sauropods such as Diplodocus and Brachiosaurus dominate the landscapes of the Jurassic.
Archaeopteryx, a transitional form between dinosaurs and birds, develops in the Late Jurassic.
In the early Cretaceous, the first angiosperms appear, drastically changing vegetation and ecosystems.
Species such as Tyrannosaurus rex, Triceratops and Ankylosaurus dominate a rich and diverse ecosystem.
A massive asteroid strikes near what is now the Yucatán Peninsula, causing worldwide devastation.
Most dinosaur species become extinct as a result of the climatic effects of the asteroid impact.
A small group of feathered dinosaurs survives the mass extinction and evolves further into modern birds.
Volcanic activity related to the breakup of Pangea, with massive CO2 emissions and climate change, caused this extinction. Many non-dinosaur archosaurs and amphibians disappeared, creating room for the diversification of dinosaurs in the subsequent Jurassic period. This event is seen as a crucial turning point in the evolution of the Mesozoic.