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In the age of dinosaurs – before whales, great whites or bus-sized megalodon – a monstrous shark roamed the waters of what is now northern Australia among sea monsters. cretaceous Duration.
Researchers study giant vertebrae discovered on a beach near the city darwin Consider that this creature is now the earliest known mega-predator of the modern shark lineage, having lived 15 million years earlier than the first known giant shark.
And it was huge. The ancestor of today’s 6-meter (20-foot) great white shark was thought to be about 8 meters (26 feet) long, the authors of a paper published in the journal Communications Biology said.
“Cardabiodontids were ancient, mega-predatory sharks that were very common from the later part of the Cretaceous, 100 million years ago,” said Benjamin Care, senior curator of paleobiology at the Swedish Museum of Natural History and one of the study’s authors. “But it has pushed back the time when we were going to find giant cardabiodontids at all.”
Rediscovered fossils point to a giant shark
The history of sharks goes back 400 million years, but Lamniformes, ancestors of today’s great white sharks, appear in the fossil record 135 million years ago. They were small at the time – perhaps only a meter in length – which suggests that lamniforms had become giant as early as 115 million years ago, which was unexpected to researchers.
The vertebrae were found on a beach near Darwin in the far north of Australia, on what was once the mud of the bottom of an ancient ocean that extended from Gondwana – now Australia – to Laurasia, in what is now EuropeIt is an area rich in fossil evidence of prehistoric marine life, with long-necked plesiosaurs and ichthyosaurs among the creatures discovered so far,
Kear said the five vertebrae that sparked the search to estimate the size of their mega-shark owners were not a recent discovery, but an old one that had been somewhat ignored. The fossils, discovered in the late 1980s and 1990s, were 12 centimeters (4.7 in) long and had been stored in a museum for years.
When studying ancient sharks, the vertebrae are prizes for paleontologists. Sharks’ skeletons are made not of bone but cartilage, and their fossil record is mostly made up of teeth, which sharks shed throughout their lives.
“The importance of vertebrae is that they give us clues about shape,” Kear said. “If you’re trying to measure it by teeth, it’s difficult. Are the teeth big and the bodies small? Are they big teeth with big bodies?”
Size of ancient shark still remains a mystery
Scientists have used mathematical formulas to estimate the size of extinct sharks such as Megalodon, which was a giant predator that arrived later and could reach 17 meters (56 feet) in length, Care said. But the rarity of the vertebrae means questions about the size of ancient sharks are difficult to answer, he said.
The international research team spent years testing different ways of estimating the size of Darwin’s cardabiodontids using fisheries data, CT scan And mathematical models, Carey said. Eventually, they arrived at a tentative picture of the predator’s size and shape.
“It would have looked for all the world like a modern, giant shark, because that’s the beauty of it,” Kear said. “This is a body model that has worked for 115 million years, like an evolutionary success story.”
A hunter’s past may hint at the future
The Darwin shark study shows that modern sharks rose to the top of prehistoric food chains early in their adaptive evolution, the researchers said. Now, Kear said, scientists can look for similar environments in others around the world.
“They may have been around before,” he said. “This thing had ancestors.”
Studying such ancient ecosystems can help researchers understand how today’s species might respond to environmental change, Kear said.
“This is where our modern world begins,” he said. “By looking at what has happened during past changes in climate and biodiversity, we can get a better idea of what may happen next.”