Creature information
Scientific name : Xiphactinus audax
Name meaning : Swift Shark
Time period : Late Cretaceous
Primary diet : Carnivore
In the programmes
Fatalities caused : One Hesperornis
Appearances : Sea Monsters (Sea Monsters, Episode 3)
In the books
That is one grotesque fish! That looks more like a bulldog than a fish. If the Devil kept fish, this would be one of them! Xiphactinus, a predatory fish up to 20 feet long.

Nigel Marven talking about Xiphactinus
Sea Monsters: To Hell... and Back?

Xiphactinus was a prehistoric predatory fish, featured in the last episode of Sea Monsters. It was over 20 feet (6 m) long and lived 85,000,000-66,036,000 BCE. A teleost, bony fish, this creature was not a close relative of the sharks, though its' name, translated from Latin, means "Swift shark".


If the Devil kept fish, Xiphactinus would be one of them. They were one grotesque species of predatory fish that looked more like bulldogs than fish. Xiphactinus could swallow a Hesperornis whole in one go. However, there are also fossils of this fish showing that it had died having choked on such large prey

Xiphactinus was a carnivore of the Cretaceous seas, but not a top one: it was prey to giant mosasaurs that lived alongside it at that time, as shown in the introduction to Sea Monsters. Itss likely, however, that if Xiphactinus lived and hunted in small shoals, it could possibly predate injured Giant Mosasaurs. itself Xiphactinus hunted anything that was smaller than itself; in the last episode of Sea Monsters, it was shown harassing both Nigel Marven and an Archelon, before, presumably, being scared away by a mosasaur pack.



SM1x3 XiphactinusEatingAHesperornis

A Xiphactinus eating a Hesperornis whole.

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