The Mesozoic Era (251.9 to 66.0 million years ago) was the "Age of Reptiles." During the Mesozoic, Pangaea began separating into the modern continents, and the modern Rocky Mountains rose. Dinosaurs, crocodiles, and pterosaurs ruled the land and air. As climate changed and rapid plate tectonics resulted in shallow ocean basins, sea levels rose world-wide and seas expanded across the center of North America. Large marine reptiles such as plesiosaurs, along with the coiled-shell ammonites, flourished in these seas. Common Mesozoic fossils include dinosaur bones and teeth, and diverse plant fossils.
The Mesozoic Era is further divided into three Periods: the Triassic, the Jurassic, and the Cretaceous. A few examples of NPS resources in each time Period are highlighted below.
Mesozoic “Age of Reptiles” Coloring Pages
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Every park contains some slice of geologic time. Here we highlight a few parks associated with Mesozoic Era. This is not to say that a particular park has only rocks from the specified period. Rather, rocks in selected parks exemplify a certain event or preserve fossils or rocks from a certain geologic age.