The discovery marks a turning point both for its enormous size and for its rarity, since it is "unprecedented" that a soft-shell egg is preserved, which according to the expert, "tends to decompose easily and not be preserved as fossils". The object has sat in Chile's National Museum of Natural History for nearly a decade, with scientists unable to determine its origin.
The mystery fossil has been now identified as a soft-shelled egg which was laid 68 million years ago.
"It looks a bit like a deflated football: elongated, collapsed, with many creases and folds on its surface".
"We suspect these large reptiles had the same reproductive strategy as viviparous lizards and snakes, which lay eggs with a very thin shell that hatch immediately after being laid", Legendre said.More news: Federation Internationale de Football Association 21 Release Date Announced, Will Support Free Next-Gen Upgrade
They analyzed the body size of 260 living reptiles, compared them with their egg sizes, and estimated that the animal that laid the mystery egg would have been roughly 7 meters long.
Furthermore, the rock formation where the egg was discovered also hosts skeletons from baby mosasaurs and plesiosaurs, along with adult specimens.
The details of the egg and its discovery were published this week in the journal Nature.
The researchers say this would demand some fancy maneuvering by the mother because giant marine reptiles were too heavy to support their body weight on land.More news: 'Ring of fire': Rare annular solar eclipse occurs on Sunday
Named Antarcticoolithus bradyi, the new fossil is the first fossilized egg found in Antarctica.
Past its record-breaking size, the researchers' finding additionally difficulties the idea that such reptiles didn't lay eggs.
"The almost-complete, football-sized soft-shelled egg is one of the largest eggs ever described", relating creator Julia Clarke, additionally of UT, said.
One involves the egg hatching in the open water, which is how some species of sea snakes give birth.
"Many authors have hypothesised that this was sort of a nursery site with shallow protected water, a cove environment where the young ones would have had a quiet setting to grow up", Dr Legendre said. The other involves the reptile depositing the eggs on a beach and hatchlings scuttling into the ocean like baby sea turtles. It looks a bit like a crumpled baked potato but measures a whopping 11 by seven inches - 28 by 18 centimetres.More news: Judge allows John Bolton book on Donald Trump's policy to be released