Xiphactinus audax was a large, predatory fish that lived during the Late Cretaceous period, around 112 to 66 million years ago. It could grow up to 20 feet long and had a distinctively large mouth with sharp teeth. This species was known for its agile swimming and aggressive hunting in the Western Interior Seaway.

Xiphactinus audax, an extinct species, was primarily found in the Western Interior Seaway of North America during the Late Cretaceous period, approximately 84 to 66 million years ago. Fossil evidence suggests that its range extended across what is now the central United States, from the Gulf of Mexico to the Arctic Ocean.

Xiphactinus audax inhabited the warm, shallow, and epicontinental seas of the Western Interior Seaway. This environment featured a subtropical to tropical climate with relatively stable temperatures and high salinity levels. The seaway was rich in marine life, providing abundant food resources.

As a large predatory fish, Xiphactinus audax occupied a high trophic level in the marine food web. Its ecological niche involved preying on smaller fish and marine reptiles, using its speed and size to capture prey. Fossil evidence suggests it had a voracious appetite, capable of swallowing prey nearly half its size.