Fossil Friday

Evidence of marine life is frequently found in Colorado despite its position as a land-locked state. During the Cretaceous Period, a shallow inland sea known as the Western Interior Seaway split North America in two. During this time, Colorado was either partially or completely underwater, allowing marine life to thrive. One prehistoric animal that made its home in the seaway was the Tylosaurus, the largest of the mosasaurs. The name Tylosaurus is Greek for “knob lizard” due to its elongated snout.

Tylosaurus could grow as large as 45 feet in length and had a fin on the end of its long tail and flippers. As a top predator in the seaway, Tylosaurus ate a varied diet consisting mostly of fish, but smaller mosasaurs, sharks, and plesiosaurs also contributed to its meals. There is also evidence Tylosaurus may have scavenged dinosaur carcasses washed out from the shore based on a bite mark on a hadrosaur fossil discovered in Alaska in 1994.   The jaw of Tylosaurus was lined with two rows of sharp teeth with two extra rows of teeth on the roof of the mouth. If something was hapless enough to swim into the mouth of a Tylosaurus, it was confronted with sharp teeth all around when the jaw shut. The museum has a tooth in the collection that was donated in 1985. The tooth was found north of Cañon City and is currently on display in the museum’s geology and paleontology exhibit.

Tylosaurus tooth, Late Cretaceous. Object ID: 1985.006.017; Royal Gorge Regional Museum & History Center collection.

The information presented in this article is compiled using research conducted by the Royal Gorge Regional Museum and History Center.    

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