Mastodons and mammoths roamed the area now known as Chicago 13,000 years ago, but any traces of marine life from 420 million years ago have disappeared.
Evidence shows that Denver was host to a battle to the death between a Tyrannosaurus Rex and a Triceratops; the Terminator Pig savages anything in its path.
A glimpse back to when prehistoric animals roamed what is now New York City.
Scimitar toothed-cats; armadillos as big as cars.
Dinosaurs and flying reptiles once roamed Washington, D.C.
In its distant past, Los Angeles was home to enormous Ice Age mammals, carnivorous dinosaurs and gigantic undersea monsters; the city emerged from the sea as tectonic plates clashed and gave birth to earthquakes that still rock the city.