巨齿鲨的传奇生命，由化石重现揭示

Museums are supposed to be havens for the collective cultural and scientific heritage of the planet, but specimens sometimes go missing.

Happily, they can also be rediscovered, as a new study shows, with the vertebrae of the legendary predatory shark known to the world under its old name of Megalodon (now properly Otodus megalodon) turning up on a museum shelf decades after they were seemingly lost.

The new paper takes another look at the size and growth of this giant shark that lived between 15 and 3.5 million years ago. The study confirms previous estimates that these animals might have been longer than 24 metres. To put that in context, even the most unnaturally exaggerated sharks in the Jaws franchise topped out at 10.5 metres. These were seriously big fish.

The work is based on an analysis of several 11-million-year-old vertebrae from one animal, found in Denmark. Apart from the jaws and teeth, shark skeletons are mostly cartilage, so vertebrae are rare and important. Compared to a tooth, they give a much better indication of the size of the owner and here these are the largest known of any O megalodon (23cm in diameter) .

These important specimens were thought to have been destroyed in a move from the Geological Museum of Copenhagen (now part of the Natural History Museum of Denmark) to the Museum of Southern Jutland in 1989. The scientific records of them were limited to old photos and descriptions. A couple of these vertebrae have now turned up, having apparently sat on a shelf unrecognised for decades. This allowed for the new study, which also estimated that a newborn O megalodon might be 3.6 metres long and live for nearly a century.

How can museums and palaeontologists lose valuable fossils?

All manner of unlikely and unfortunate actions can lead to the loss of fossils from museums.

Most obviously this can happen during times of conflict. The second world war saw the loss of dinosaur fossils on both sides of the conflict. The original specimens of the sail-backed dinosaur Spinosaurus were destroyed in Munich by an allied bombing raid in 1944. Earlier, a number of specimens, including parts of the early dinosaur Thecodontosaurus, were destroyed in Bristol after an Axis raid in 1940.

These were not even the first losses from enemy action in international wars. In 1916, the Canadian ship SS Mount Temple was sunk by a German ship. Although it was mostly carrying wheat, it also had a cargo of dinosaur fossils from Alberta that were being moved to the UK. The cargo lists are vague so we don’t even know what dinosaurs were on board.

Indirect action could be problematic too. In 1941, the Chinese attempted to move as many as 40 specimens of “Peking man” (Homo erectus) , the first of our relatives to have human-like proportions, to the US to try to save valuable early hominid fossils from the invading Japanese forces. They never arrived, and might have been lost at sea after the ship they were on was sunk. Although it’s possible they never even made it on board the vessel.

Things can also be simply lost or fall apart. An apparent giant sauropod dinosaur similar to Diplodocus was named by the US palaeontolgist Ed Cope in 1877 as Amphicoelias fragillimus. He described it from a single, incomplete, fragile, but giant, vertebra.

Cope gave differing measurements of the vertebra at various times, making it unclear quite how large it actually was. When he died, his collection was sold to the American Museum of Natural History, but they were never able to find this specimen. Given how fragile it was, it may simply have disintegrated on the shelf and been overlooked or thrown away.

Museums are not immune to losses either. If you have an enormous number of specimens (the Natural History Museum in London has an estimated 80 million objects in its collection) , it is inevitable that one or two may simply get lost.

I’ve been an eyewitness to lost specimens turning up in a museum when a colleague spotted a dinosaur skull and pterosaur skeleton sitting on the wrong shelf like misplaced library books. Then there’s the more nefarious activities – I’ve heard of researchers deliberately moving specimens to make them hard to find so other researchers cannot examine them, and occasionally things are stolen from collections.

On top of this, natural disasters and accidents can wipe out history. The Fukushima earthquake and tsunami of 2011 in Japan caused major damage to the nearby Iwaki museum with damage to some of the fossils in their collections. And in 2018, one wing of the Nation Museum of Brazil in Rio de Janeiro burned down with the loss of many fossil specimens that were on display.

For all the examples raised here, museums are inherently safe places for specimens. There are millions and millions of fossils that have been held in institutions around the world for decades and even centuries. It is inevitable that accidents will happen, and that bad actors will cause occasional losses. Fortunately, at least on occasion these do reappear and give us some exciting new research opportunities.

David Hone does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.