Mesozoic Era	Triassic Period	Late Triassic	Jurassic Period	Late Jurasic	Cretaceous Period	Late Cretaceous
Context	The beginning of the "Age of Dinosaurs"	The final stage of the Triassic marked by life recovering from the "Great Dying" and the very first dinosaurs carving out their niche	This period saw dinosaurs rise from one of many reptile groups to the undisputed masters of the planet. (The Age of Giants)	The "Golden Age" of giants reached its peak, especially in North America's Morrison Formation.	The peak of dinosaur diversity and the "High Noon" of their reign.	The most famous era of dinosaur history, ending in a sudden global catastrophe.
Years	252-201 million years ago	237-201 million years ago	201-145 million years ago	163-145 million years ago	145-66 million years ago	100-66 million years ago
Geography	All continents were united in the supercontinent Pangea. The land was mostly desert	All continents were united in the supercontinent Pangea. The land was mostly desert	The supercontinent Pangea began to rift apart into Laurasia (North) and Gondwana (South), creating the early Atlantic Ocean.	Laurasia and Gondwana were fully separated by the young Atlantic Ocean.	Continents drifted toward modern positions; high sea levels created shallow inland seas.	Continents looked nearly modern, but a "Western Interior Seaway" split North America in half.
Life	Early dinosaurs like the Eoraptor and Plateosaurus were small and fast	Early mammals appeared, along with the first pterosaurs. Seed ferns like Dicroidium dominated the southern flora.	The first birds (like Archaeopteryx) appeared, and early mammals diversified into small, shrew-like forms. Oceans teemed with ichthyosaurs and plesiosaurs.	The first birds like Archaeopteryx appeared, and reef-building corals flourished in the seas.	Appearance of flowering plants, bees, and ants.	Flowering plants (magnolias, oaks) became common, and modern-style mammals began to diversify.
Dominant Dino	Pseudosuchian	Coelophysis and Plateosaurus	Giant Sauropods (long-necks) like Brachiosaurus	Brachiosaurus, Diplodocus, and the plated Stegosaurus	Large Theropods like T. rex and horned dinosaurs	Tyrannosaurus rex, Triceratops, and the armored Ankylosaurus
Climate	Arid and hot; vast deserts covered the interior of Pangea	Highly seasonal with intense monoons; the "Carnian Pluvial Episode" brought a long period of heavy rain to the dry deserts	Warm and humid; the world turned green with lush ferns and conifers	Warm and steady; sea levels rose, creating many tropical island chains in Europe	Tropical "greenhouse" conditions; no ice at the poles	A "super-greenhouse" world; even the poles were covered in lush forests rather than ice
End	Mass extinction clearing the way for larger dinosaurs	Concluded with the Triassic–Jurassic extinction event around 201 million years ago, likely caused by massive volcanic eruptions during the initial breakup of Pangea.	A minor extinction event and a shift in sea levels, but no total "reset."	A sea-level shift and minor extinction event that saw the decline of the massive "long-neck" sauropods in the north.	A 6-mile-wide asteroid hit the Yucatan Peninsula, causing a global firestorm and "impact winter."	A massive asteroid impact (Chicxulub) combined with volcanic activity (Deccan Traps) wiped out all non-avian dinosaurs.