In 2011, Chilean scientists discovered a football-sized fossil off the coast of the island of Seymour near the northern tip of the Antarctic Peninsula. Although they didn’t know what it was at the time – and simply called it “The Thing” – new research shows that it is not only the first fossil egg ever found in Antarctica, but also the largest soft-shelled egg that was ever found anywhere.
In a study published today in the science journal natureResearchers from the University of Texas at Austin and the University of Chile dated the offshore rock formation in which the fossil egg from the late Cretaceous period ̵
But the eggs don’t have much in common beyond their size; An elephant bird egg is about five times thicker than this fossil egg, and its hard shell has clear pores and a prismatic layer that the fossil egg lacks. In other words, an elephant birding resembles a giant chicken egg. (And giant is no exaggeration – an elephant bird egg could contain the content of about 150 chicken eggs.)
With its soft shell and elongated shape, the new fossil egg from the new taxon Antarcticoolithus bradyimore like a lizard or snake egg, suggesting that it might have been laid by a large reptile. To test this theory, the researchers compared it to the egg properties of 259 species of lepidosaurs – a subclass of reptiles, which include snakes and lizards – and suspected that the egg layer may have been a marine reptile that was about 7 meters was large) or longer.
The researchers believe that this mysterious mother could have been a Mosasaur, a type of large marine lepidosaur whose remains were also discovered in the area. During the Late Cretaceous Period, Mosasaurs were among the most formidable predators in the ocean. They had strong fins and sharp teeth, and some species grew up to 50 feet long (although that’s still a good 10 feet shorter than the fictional Mosasaur that was portrayed in the 2015s Jurassic World). Petrified stomach contents show that they enjoyed a variety of wildlife, including fish, seabirds, turtles, plesiosaurs, and more – a Mosasaur had even eaten some other Mosasaurs. And although Mosasaurs lived in Antarctica, the continent didn’t look like its current cold landscape in the Late Cretaceous Period.
“Antarctica was rich in life,” says Dr. Julia Clarke, professor at the Department of Geological Sciences at UT Austin and co-author of the study, told Mental Floss. “Temperate forests with different types of plants covered exposed land. Huge marine reptiles and much smaller ammonites and relatives of live birds that were hunted in the oceans while medium-sized non-bird dinosaurs strolled ashore. “
As scientists have discovered the remains of Mosasaurs and Plesiosaurs of all ages in the rock formation where the fossil egg was found, some believe that it could have been a popular place for creatures to hatch and raise their young.
“Many authors have hypothesized that this was kind of a shallow, protected water kindergarten, a cove where the boys would have had a quiet environment to grow up in,” said Lucas Legendre, postdoctoral researcher and lead author of the study. said in a press release.
If the fossil egg really belongs to a Mosasaur, it could change our understanding of how Mosasaurs were born. In the 1990s, scientists in South Dakota discovered the skeleton of a lizard-like Mosasaur named a Plioplatecarpus preserved with five unborn offspring in the abdomen. Since they were not in eggs, it was generally believed that Mosasaurs gave birth to a young life. The existence of Antarcticoolithus bradyiHowever, this suggests the possibility that some Mosasaurs laid soft-shelled eggs that hatched immediately afterwards.
Clarke says the discovery of fossil egg is particularly exciting because it shows “how much we still have to learn about egg development, from the first layers of egg that moved away from the water to the immense variety of eggs and reproductive strategies we see today. “