When paleontologist Dean Lomax was plumbing the depths of a fossil collection at Yale University’s Peabody Museum of Natural History in 2016, one dusty specimen caught his eye. It resembled a crocodile compressed onto a slab of slate. Flaking paint and specks of white plaster revealed the “skeleton” was actually a carefully constructed plaster cast—and that it was of no crocodile.
Although Lomax, a paleontologist at the University of Manchester, had never visited the Peabody’s collection before, the specimen looked strangely familiar. But it was not until he sifted through his photographs afterward that the connection clicked: The cast was nearly identical to a historic illustration of the first known Jurassic “sea dragon” skeleton. Three years later, he stumbled upon a similar cast in Germany.
Both casts, it turns out, were made from the same specimen: the skeleton of a nearly 200-million-year-old marine reptile known as an ichthyosaur, which had wide eyes, the body of a dolphin, and the toothy maw 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 finds 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 the Peabody’s vertebrate paleontology department who helped Lomax study the Yale cast but is not an author of the new study. The new casts offer an opportunity to see just how well historical illustrations match up with the specimens themselves, he says. “This report will have people taking 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 paleontology field. The first complete ichthyosaur skeleton hailed from Lyme Regis, a seaside town along southern England’s iconic Jurassic Coast. Eroding out of the area’s wave-battered limestone cliffs are the inhabitants of a tropical sea from 200 million years ago, including squidlike ammonites, pterosaurs, and a slew 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 uncovered an entire ichthyosaur skull by the time she was 12. At 18, she discovered the most complete ichthyosaur specimen known at the time—the skeleton that became the source of the two rediscovered casts.
The remarkable find 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 jigsaw puzzle,” Lomax says.
The fossil passed into the hands of a collector, who later sold it to help the Anning family through financial hardship. Eventually, the skeleton ended up in the collection of London’s Royal College of Surgeons, where it was studied by British surgeon Sir Everard Home. Based on the creature’s flattened, disk-shaped vertebrae, he erroneously concluded that ichthyosaurs were a link between lizards and salamanders. In total, Home published five papers on ichthyosaur specimens unearthed by Anning, failing every time 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 the only remaining evidence of the first complete ichthyosaur specimen was the scientific illustration that accompanied Home’s papers.
Then came Lomax’s discovery of the two casts—one in the storerooms of the Natural History Museum in Berlin, a somewhat ironic home given the fiery fate of the original specimen.
Although the two casts are based on the same source material, they are not identical. The older Yale specimen is more deteriorated and painted a uniform shade of ashen gray, whereas the Berlin cast is in better shape and has been painted to resemble the 1819 illustration. The Yale cast also appears to be a better 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 intricate bones in the creature’s fore fins and the shape of the animal’s humerus—that differ from the other two representations. These minute details, along with age of the crumbling plaster, makes it likely that the Yale cast was among the first casts made, potentially even predating the skeleton’s arrival in London and description by Home. “They go from being just another cast in the collection to a representation of the first ichthyosaur skeleton described right at the beginning of paleontology,” Lomax says.
When researchers don’t replicate rare fossils with casts, the results can be disastrous. The first fossil evidence of the giant predatory dinosaur Spinosaurus was destroyed during an allied bombing of Munich in 1944, leaving behind only illustrations and grainy photographs. The predator was little more than a sail-backed enigma for half a century until researchers unearthed new fossil evidence.
Such losses are still occurring. Megan Jacobs, a paleontologist studying ichthyosaurs at the University of Portsmouth, highlights the 2018 fire that devastated the National Museum of Brazil, which destroyed a cache of prized pterosaur fossils, as a worst case scenario. “They lost almost everything and those were the only examples of those fossils in the world,” she says.
However, with the advent of 3D scanning technology, creating casts is becoming even easier as museums pivot to digitizing important fossils. Jacobs says: “There’s really no excuse not to do it.”