Replicas of long-lost ‘sea dragons’ discovered in museum collections | Science

When paleontologist Dean Lomax was plumbing the depths of a fossil collection at Yale University’s Peabody Museum of Natural History in 2016, a dusty specimen caught his eye. He looked like a crocodile compressed on a slate slab. Peeling paint and patches of white plaster revealed that the “skeleton” was in fact a carefully constructed plaster cast – and that it was not a crocodile.

Although Lomax, a paleontologist at the University of Manchester, had never visited Peabody’s collection before, the specimen looked oddly familiar. But it wasn’t until he sifted through his photographs that the connection was made: the cast was nearly identical to a historical illustration of the earliest known Jurassic “sea dragon” skeleton. Three years later, he came across a similar cast in Germany.

It turns out that both casts were made from the same specimen: the skeleton of a nearly 200 million year old marine reptile known as an ichthyosaur, which had large eyes, the body of a dolphin and the toothy mouth of an alligator. The original skeleton had been destroyed in a bombing raid on London during World War II, making the two casts the only known records of this animal, Lomax reports today.

The findings will allow scientists to study the historic ichthyosaur in unprecedented detail, experts say. Paleontologists had relied solely on a 200-year-old illustration of the creature, notes Daniel Brinkman, a museum assistant in Peabody’s Department of Vertebrate Paleontology who helped Lomax study the Yale cast but is not the author of the new study. The new casts provide an opportunity to see how closely historical illustrations match the specimens themselves, he says. “This report will get people to take a closer look at some of their casts.”

Decades before the word “dinosaur” entered the scientific lexicon, ichthyosaurs were the rock stars of the nascent field of paleontology. The first complete ichthyosaur skeleton hails from Lyme Regis, a seaside town along the iconic Jurassic Coast in southern England. Inhabitants of a tropical sea from 200 million years ago erode the area’s wave-battered limestone cliffs, including squid-like ammonites, pterosaurs and a host of marine reptiles including ichthyosaurs and long-necked plesiosaurs.

Fossil hunters have flocked to these crumbling cliffs for centuries, thanks in part to the prodigious collecting of pioneering paleontologist Mary Anning in the early 1800s. The daughter of an amateur fossil hunter, Anning and her brother had discovered an entire ichthyosaur skull at the age of 12. At age 18, she discovered the most complete ichthyosaur specimen known at the time, the skeleton that became the source for the two rediscoveries. throw.

This remarkable discovery offered early paleontologists a tantalizing glimpse of what these puzzling prehistoric reptiles really looked like. “This specimen was a major piece of the gigantic prehistoric puzzle,” says Lomax.

The three surviving depictions of the first complete ichthyosaur skeleton, including the 1819 illustration (top), the Yale cast (middle), and the Berlin cast (bottom)William Clift/Royal Society

The fossil passed into the hands of a collector, who then sold it to help the Anning family through financial difficulties. Eventually, the skeleton ended up in the collection of the Royal College of Surgeons in London, where it was studied by British surgeon Sir Everard Home. Based on the creature’s flattened disc-shaped vertebrae, he incorrectly concluded that ichthyosaurs were a link between lizards and salamanders. In total, Home published five papers on ichthyosaur specimens discovered by Anning, each time failing to credit her as the discoverer.

More than a century later, in 1941, a bomb from a German air raid destroyed the London museum that housed the iconic fossil. And for decades, it appeared that the only remaining evidence of the first complete ichthyosaur specimen was the scientific illustration that accompanied Home’s articles.

Then came Lomax’s discovery of the two casts – one in the storerooms of Berlin’s Natural History Museum, a somewhat ironic home given the original specimen’s fiery fate.

Although both distributions are based on the same source material, they are not identical. The older Yale specimen is more deteriorated and painted a uniform shade of ash gray, while the Berlin cast is in better shape and has been painted to resemble the 1819 illustration. The Yale cast also appears to be a best representation of the original skeleton, Lomax and his co-author, State University of New York, Brockport, paleontologist Judy Massare, conclude today in Royal Society Open Science.

Where the Berlin cast is clearly based on the 1819 illustration, for example, the Yale cast has several traits – including the number of complex bones in the creature’s fore flippers and the shape of the humerus of the animal – which differ from the other two representations. These painstaking details, along with the age of the crumbling plaster, make it likely that the Yale cast was among the first casts made, potentially even before the skeleton arrived in London and was described by Home. “They go from just one more cast in the collection to a representation of the first ichthyosaur skeleton described from the beginning of paleontology,” says Lomax.

When researchers don’t reproduce rare fossils with casts, the results can be disastrous. The first fossil evidence of the giant predatory dinosaur Spinosaurus was destroyed in an Allied bombing of Munich in 1944, leaving behind only grainy illustrations and photographs. The predator was little more than a sail-backed enigma for half a century until researchers uncovered new fossil evidence.

Such losses still occur. Megan Jacobs, a paleontologist who studies ichthyosaurs at the University of Portsmouth, highlights the 2018 fire that devastated the National Museum of Brazil, which destroyed a cache of valuable pterosaur fossils, as the worst case scenario. “They lost almost everything and these are the only examples of these fossils in the world,” she says.

However, with the advent of 3D scanning technology, creating casts is becoming even easier as museums shift to digitizing important fossils. Jacobs says, “There’s really no excuse not to.”

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