Resurrecting the Shark by Susan Ewing

Author:Susan Ewing
Language: eng
Format: epub
Publisher: Pegasus Books
Published: 2017-04-21T04:00:00+00:00

10

THE NEW GUARD

What of the sawfish? What on earth is that all about? And the hammerhead shark?

—Richard Dawkins, The Ancestor’s Tale: A Pilgrimage to the Dawn of Evolution, 2004

IN 2009, THE GREAT NEEDLE-AND-THREAD OF CHANCE WHIP-STITCHED RUSSIA BACK into the Helicoprion story when paleontologist Oleg A. Lebedev published a paper on a previously undescribed tooth whorl. Lebedev stumbled across the fossil in a drawer at the Paleontological Institute of the Russian Academy of Sciences in Moscow. He had been a year old when paleontologist Vasiliy E. Ruzhentsev originally collected the specimen in Kazakhstan in 1958, apparently while mapping Permian-age rocks and hunting for fossil cephalopods. It wasn’t the first or last time this paleontological coincidence between Helicoprion and cephalopods occurred. In 1995, Canadian paleontologist and ammonoid expert W. W. Nassichuk wrote, “Curiously, representatives of the coiled shark tooth structure Helicoprion occur with [Permian] ammonoids in both Idaho and the Arctic Islands.” Lebedev himself would soon reveal the conflux to be about as coincidental as fox tracks circling a chicken coop.

Ruzhentsev’s fossil was a badly battered whorl broken into two sickle-shaped fragments. The larger fragment, a section of the whorl’s outer perimeter, held evidence of twenty-six teeth, though all the crowns were broken off. The smaller piece was an inner section of whorl in noticeably better shape, with fifteen complete or nearly complete tooth crowns. Lebedev estimated that, in its intact state, the whorl would have been nearly sixteen inches in diameter with up to 140 teeth total. Ruzhentsev, not particularly interested in fish and possibly unimpressed by the much-deteriorated fossil, had given it to Dmitry Obruchev, a logical handoff since Obruchev had recently published his well-illustrated retrospective of Karpinsky’s Helicoprion work. But Obruchev never published anything on Ruzhentsev’s specimen, and the fossil lay unnoticed for nearly fifty years until it caught Lebedev’s eye. While the fossil caught Lebedev’s eye, the location of the find is what really captured his attention. Ruzhentsev found the fossil in the Kazakh region of the Ural Mountains, the same range but a significant distance away from the quarry where Karpinsky’s stunning whorl had been discovered a century before. That made Ruzhentsev’s fossil the southernmost Helicoprion ever collected on the western slope of the Urals, which indicated something very significant about Helicoprion’s distribution and range.

Here we recall the Helicoprion we met previously, Karpinsky’s Helicoprion, swimming up the west coast of Pangaea. The big shark was following signals from its ampullae of Lorenzini, those jelly-filled sensory pores, to turn east into the Uralian Seaway—the thousands-miles-long “shortcut” from the Panthalassic Ocean to the Tethys Sea. According to Lebedev’s estimation, Ruzhentsev found his Helicoprion fossil at what once had been the junction of the Uralian Seaway and the northern Tethys. Unlike the Helicoprion that ended up on Karpinsky’s work table, which died about halfway down the seaway, Ruzhentsev’s Helicoprion had navigated its entire length. Or perhaps was on its way back to the Panthalassic Ocean. Regardless of which way it was going, the discovery provided connect-the-dots evidence that Helicoprion was a “cosmopolitan” shark—global and widespread.

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