Diggin' For Dinosaurs - Berlin-Ichthyosaur

Berlin-Ichthyosaur State Park, Nevada

Tucked against the western slope of the Shoshone Range sits the weathered ghost town of Berlin, Nevada. At the turn of the century, gold and silver ore mines supported 250 residents in Berlin and nearby camps. The miners knew about other, stranger stuff here, too, like spool-shaped fossilized bones the size of dinner plates, and, indeed, some reportedly used these bones as dinner plates.

It's hard to imagine today, when one is looking west across a sea of sagebrush to the Paradise Range, but in the late Triassic, about 220 million years ago, central Nevada lay beneath an ocean, and in that ocean swam the world's largest ichthyosaurs.

Just as dinosaurs ruled the land and pterosaurs the sky, ichthyosaurs were the masters of Mesozoic seas. Found on all continents except Antarctica, these marine reptiles appeared on Earth around the time of the first dinosaurs and lasted for as long - 160 million years - before succumbing near the close of the Cretaceous. They thrived in a global ocean that encircled the supercontinent called Pangaea. The 57 alleged species that have been found range in size from two to 60 feet long. Built like tunas, with powerful tails and streamlined bodies, ichthyosaurs had eyes up to a foot across, perfect for spotting squid in dark water and snapping them between jaws lined with pointed teeth. Dense ribs girded these reptiles during descents to crushing depths.

The 37 specimens found eroding out of a sandstone hill two miles from Berlin's mine shafts and stagecoach station - fossils of an industrial age - came to scientific attention in 1928. But nearly 30 years passed before Charles Camp and Sam Welles of the University of California Museum of Palaeontology mounted an excavation. Camp described three ichthyosaur species here, the largest being 40-ton Shonisaurus popularis, up to 50 feet long with six-foot, paddlelike flippers. He developed a scenario in which the creatures were marooned by a receding tide on a bay mudflat, like confused whales that beach themselves. A more recent study concluded that the carcasses simply sank to the bottom of the sea and were buried beneath 600 feet of sediment, although some palaeontologists argue that such a gradual burial would be unlikely to produce fossils.

At Camp's urging, an A-frame shelter was built over the fossil site in 1966, leaving in place the remains of either nine or 10 ichthyosaurs - no one can tell for sure. You can peer through windows at either end of the shelter, but it's worth taking a guided tour of the interior. A ranger will point out the various parts of each skeleton, which is helpful since it takes a little imagination to connect the bones and flesh them out into massive marine hunters.

If you've seen pictures of the amazingly intact ichthyosaurs from German shale (where fetuses have been preserved inside the womb or exiting the birth canal), the Berlin specimens are a bit of a letdown. Maybe it's the lack of faces; ichthyosaur skulls contained a lot of cartilage and did not readily preserve as fossils. You'll have to settle for flipper bones, coracoids (which held flippers to the chest), rib cages, and lots of those spool-shaped vertebrae, stacked up like dominoes. In one specimen it's possible to discern the outline of the giant eyeball, larger than that of any vertebrate before or since.

You can't fail to be impressed by the beasts' magnitude. Not only is Nevada's state fossil the world's largest ichthyosaur, some 20 feet longer than the closest contender, but Shonisaurus was the largest animal of all in Triassic seas and rivaled in size the world's biggest living fish, the whale shark.

Continued in: Diggin' For Dinosaurs - Fossil Butte

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