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Xiphactinus (Wikimedia Commons)


Xiphactinus (combination Latin and Greek for "sword ray"); pronounced zih-FACK-tih-nuss


Shallow waters of North America

Historical Period:

Late Cretaceous (90-65 million years ago)

Size and Weight:

About 20 feet long and 500-1,000 pounds



Distinguishing Characteristics:

Large size; prominent teeth


About Xiphactinus:

Xiphactinus was the largest bony fish of the Cretaceous period, but it was far from the top predator of its North American ecosystem--as we can tell from the fact that specimens of the prehistoric sharks Squalicorax and Cretoxyrhina have been found containing Xiphactinus remains. It's a fish-eat-fish world, though, so you shouldn't be surprised to learn that numerous Xiphactinus fossils have been discovered containing the remains of smaller fish. (Finding a fish inside a fish inside a shark would be a true fossil trifecta!)

One of the most famous Xiphactinus fossils contains the almost-intact remains of an obscure, 10-foot-long Cretaceous fish called Gillicus. Paleontologists speculate that the Xiphactinus died right after swallowing the fish, possibly because its still-living prey managed to puncture its stomach. If this is what happened, Xiphactinus would be the first fish proven to have died from acute indigestion.


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