Date: late Cretaceous Period (145-65 million years old)
Description: Sticking out of this rock is a fish that was fossilized and preserved inside the rock millions of years ago. The species has not been identified, and the fish cannot be removed for fear of damaging the specimen. It is from the late Cretaceous Period, when bony fish were very common in the ancient Midwest seas. The fossil was found near Platte, South Dakota, which was covered over the same Western Interior Sea as Sioux City. There are no dinosaur fossils in this region (except for the occasional aquatic species like plesiosaurs) because Siouxland was covered by this vast sea.
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