The big fish that went away . . .

From Denver, at a meeting of the Society of Vertebrate Paleontology

FINE CATCH. Artist’s concept of Xiphiorhynchus rotundus, an ancient billfish related to modern-day swordfish. Fierstine

Deep-sea anglers, sit back in your deck chairs, close your eyes, and imagine fighting to land one of the monstrous fish that cruised the seas off South Carolina about 26 million years ago. Fossils found near Charleston suggest that adult members of Xiphiorhynchus rotundus, an extinct species of billfish related to today’s swordfish and marlin, would easily exceed the lengths documented for world-record specimens of those oft-sought fish.

For a long time, X. rotundus was known only from a fossilized portion of its distinctive upper bill, says Harry Fierstine of California Polytechnic State University in San Luis Obispo.

Now, paleontologists have unearthed a few of the species’ vertebrae, which measure up to 14.7 centimeters long and 10.9 cm in diameter. By comparing the X. rotundus dimensions with those of vertebrae from a closely related, extinct European species, Fierstine estimates that the largest of the South Carolina specimens was at least 5.1 meters long—comparable in length to a big alligator. Because the number of vertebrae in ancient billfish species ranged from 24 to 26, X. rotundus could have been even longer. In any case, it’s the longest billfish in the fossil record.

One of today’s largest billfish is the black marlin, notes Glenda Kelley, a biologist with the International Game Fish Association in Dania Beach, Fla. The organization’s rod-and-reel record for that species—a 4.4-m-long, 708-kilogram whopper—was hauled onboard a boat after an epic battle lasting 1 hour and 45 minutes off the coast of Peru in August 1953.

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