A new study shows that a giant reptile egg discovered in Antarctica was laid by a 23-foot (7.1 m) marine monster 66 million years ago.
Geologists from the University of Texas believe that the 11-inch egg was produced by a creature the size of a large dinosaur, but coincidence that it is completely different from any known dinosaur egg.
The soft-shelled egg belongs to the ancient sea lizard known as musação, and is only the second in size relative to the extinct egg of the elephant bird in Madagascar.
The rocks in which the egg was found also host skeletons of fossils, and other prehistoric marine creatures called pleasiosaurs.
The lead author, Dr. Lucas Legendre, a geologist at the University of Texas, said the egg was more similar to lizards and snakes.
Aside from its stunning proportions, the discovery challenges the prevailing notion that such giant marine animals did not lay eggs.
Correspondent Professor Julia Clark, of UT, also said that an egg with a full-size, soft-shelled shell the size of football changed our understanding of the creatures of this period.
Their lineage and thin shell – which lacks the crystalline outer layer – indicates that the predator was “ovoid and friendly”, which means that the egg develops inside the mother and hatches once laid.
The team said that the mother who laid this egg, is called Antarcticitholus brady. It was discovered in Lopez de Bertodano on Seymour Island, part of the Antarctic Peninsula, where the prehistoric region was ice-free and warmer, with forests covering most of the land.
The egg may have hatched in open water – this is how some types of marine snakes give birth – or it can be deposited on shore.
The giant marine reptiles were so heavy that they could not bear their body weight on the ground. Laying eggs requires reptiles to warp their tail on the beach while mostly staying with water.
The fossilized egg was discovered by Chilean scientists in 2011 but has not been classified in the collections of the National Museum of Natural History in Chile, for nearly a decade.
Now, the analysis confirmed the existence of the sample as the first fossil egg found in Antarctica. The researchers said the skeleton is very similar to the fast-hatching transparent eggs laid by some snakes and lizards today.