Western Interior Seaway
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The Western Interior Seaway was a large inland sea that existed roughly over the present-day Great Plains of North America, splitting the continent into two major landmasses, Laramidia to the west and
A broken concretion with fossils inside; late Cretaceous Pierre Shale near Ekalaka, Montana.
Monument Rocks (Kansas), located 25 miles south of Oakley.
Artist's impression of a Cretoxyrhina and two Squalicorax circling a dead Claosaurus in the Western Interior Seaway
Inoceramus, an ancient bivalve from the Cretaceous of South Dakota.
Cretaceous
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The Cretaceous is a geological period that lasted from about 143.1 to 66 Ma. It is the third and final period of the Mesozoic Era, as well as the longest. At around 77.1 million years, it is the ninth
The impact of a meteorite or comet is today widely accepted as the main reason for the Cretaceous–Paleogene extinction event.
Drawing of fossil jaws of Mosasaurus hoffmanni, from the Maastrichtian of Dutch Limburg, by Dutch geologist Pieter Harting (1866)
Scipionyx, a theropod dinosaur from the Early Cretaceous of Italy
Facsimile of a fossil of Archaefructus from the Yixian Formation, China