Every time we have imagined a dinosaur egg, we have done so by evoking a large egg with a hard shell that the young would break at birth. Science also supported this theory. Up to now. A new study by scientists at the American Museum of Natural History has discovered in Antarctica the first fossil dinosaur egg the size of a deflated soccer ball – or a huge wrinkled potato – that has been dubbed “The Thing.” Thing); and it does not have a hard shell.
Experts estimate that it is about 68 million years old, a date close to the extinction event of most dinosaurs due to a meteorite about 10 kilometers in diameter (66 million years ago during the Cretaceous).
A rather unusual find
Its size is staggering: it measures 28 x 7 centimeters; It is the largest soft-shelled egg ever discovered (and the second largest when compared to any known animal, such as the now-extinct elephant bird). It far exceeds the limits of how large soft-shelled eggs could grow, according to scientists. In addition to its size, the fossil is significant because scientists believe it was laid by an extinct giant marine reptile, a discovery that challenges the prevailing thinking that such creatures did not lay eggs.
“It’s from an animal the size of a large dinosaur, but it’s completely different from a dinosaur egg,” said Lucas Legendre, a postdoctoral researcher at the Jackson School of Geosciences at the University of Texas Austin, and leader of the study that publishes the journal. Nature . “It is very similar to the eggs of lizards and snakes, but from a truly giant relative of these animals.”
What animal laid such a huge egg?
The egg fossil does not have a skeleton inside to confirm the species, but analysis of sections of the remains revealed “a layered structure similar to a soft membrane and a much thinner hard outer layer, suggesting that it had a soft shell. This was also confirmed by chemical analysis, which showed that the eggshell is distinct from the sediment around it, and was originally a living tissue, “the authors explain.
According to experts, the egg did not belong to a dinosaur, as those living in Antarctica at that time were too small to have conceived an egg of such magnitude. Instead, they believe it came from a species of reptile, possibly a group known as mosasaurs, that were common in the region. To reinforce this theory, the egg was found at a site where skeletons of baby mosasaurs and other marine reptiles called plesiosaurs have been found.
It was previously believed that the giant marine reptiles of the Cretaceous did not lay eggs, yet “nothing like this has ever been discovered.”
It is also unclear how the animal hatched . It could be that the mother laid the egg in open water in the same way as modern sea snakes, or that the reptile crawled to shore (it would have been too heavy to support its own body weight) and used its tail to create a nest. before their young slipped into the sea like sea turtles do today.
“Many authors have hypothesized that this was a type of nursery with protected shallow waters, an inlet environment where the young would have had a quiet environment to grow up,” say the experts.
Referencia: A giant soft-shelled egg from the Late Cretaceous of Antarctica, Nature (2020). DOI: 10.1038/s41586-020-2377-7 , www.nature.com/articles/s41586-020-2377-7
