A mysterious 68 million-year-old fossil found on Seymour Island, off the coast of Antarctica, that looked like a deflated soccer ball, turned out to be a unique find – the second largest egg on record and that may have belonged to a huge marine reptile that lived alongside dinosaurs.
The fossilized egg, measuring 29 by 20 centimeters, is only slightly smaller than the eggs of Madagascar's giant flightless elephant birds that became extinct only in recent centuries, scientists said on Wednesday. 19659003] While birds, crocodiles, and many dinosaurs laid hard-shelled eggs, the Antarctic egg had a soft, parchment-like shell.
"This new egg is the first fossil egg in Antarctica, and the largest soft-shelled egg ever discovered," said University of Texas paleontologist Lucas Legendre, lead author of the research published in the journal Nature.
"It looks a bit like deflated football: elongated, collapsed, with many folds and surface folds. One side is flattened, suggesting that this is where it came into contact with the sea floor. Its eggshell is very thin and little mineralized, as in the eggs of lizards and snakes ".
The only creatures in Antarctica at that time large enough to lay such an egg were marine reptiles: marine lizards called mosasaurs and long-necked plesiosaurs. The fossil challenges the notion that these animals did not lay eggs and were completely viviparous, giving birth to live young.
"We suspect that 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 lay," said Legendre.
The egg had no embryonic remains and the mother's skeleton was not found to identify which animal laid it. Among the candidates are species of mosasaurs g 15 meters long and plesiosaurs reaching 10 meters long, Legendre said.
Mosasaurs and plesiosaurs went extinct at the same time as dinosaurs after an asteroid hit Earth 66 million years ago.
Scientists from the University of Chile and the Museum of Natural History of the country found the fossil in 2011. Initially puzzled by it, they nicknamed it "The Thing", by the name of a science fiction movie.
"When we arrived at the camp, we asked the geologists who accompanied us if they had ever seen anything like this," said paleontology researcher at the University of Chile, Rodrigo Otero. "His puzzled expression said it all"