Soft egg fossil from Antarctica was credited with a seven-meter mosasaur

Paleontologists have studied the fossil of a giant egg found in the Cretaceous deposits of Antarctica, and came to the conclusion that it belonged to a seven-meter mosasaur — predatory marine reptiles, related to modern monitor lizards. This is the largest known eggs with a soft shell. Detailed description of the findings is given in an article published in Nature.

In the Cretaceous period, the territory of Antarctica was covered by dense forests, in which flourished dinosaurs and other animals. Equally rich was the fauna of coastal waters. Unfortunately, data about this lost world is very incomplete. This is not surprising because to look for fossils on the ice-covered continent is very difficult.

However, sometimes working in Antarctica, paleontologists are able to make amazing discoveries. For example, in 2011, was discovered an unusual fossil, resembling a giant egg with a length of about 30 centimeters. Her age was estimated at 68 million years. For nearly ten years remained unknown whether this finding is real egg, it was also unclear to whom it belonged. To solve the mystery managed a team of paleontologists, under the leadership of Julia Clark (Julia A. Clarke) from the University of Texas at Austin.

Using a few high-tech methods, including electron microscopy and x-ray spectroscopy, the scientists confirmed that the fossil is really a fossil egg first discovered in Antarctica. The embryo inside was not, however, the structure of the shell is preserved perfectly. It did not contain a prismatic layer and, most likely, was elastic.

For eggs with soft shells the discovery was very difficult: the calculations showed that she weighed six pounds. As large eggs set aside some naticia dinosaurs and birds (e.g., the recently extinct Malagasy aepyornis (Aepyornis maximus)), but they were characterized by a hard shell. The most severe of the known soft egg weighs only 700 grams.

The structural features of the shells found in fossil eggs, is characteristic only for one group of animals — reptiles from the order squamate (Squamata). It is treated a variety of lizards and snakes. Comparing body length and egg size 259 modern representatives of the order, the authors came to the conclusion that a giant egg belonged to an animal with a body length of more than six and a half meters. This allowed to attribute the find to mosasaurus — predatory marine reptiles, related to lizards. In the Cretaceous era, this group was widely distributed throughout the World ocean.

Traditionally, mosasaurs have been asciiportal, that is, kept the eggs in the oviducts until the young were hatched. The new find is consistent with this hypothesis. Its dimensions also indicate that over time the mosasaurs gave birth to a few young but invest a lot of resources into their development — that is adhered to the K-strategy.

In Antarctic marine sediments from the Cretaceous period have been found the remains of mosasaurs. However, to determine which particular species of reptiles belonged to a giant egg, it is impossible. Therefore, scientists decided to describe it as oowada — that is, a taxon described on the basis of the found eggs. He was named Antarcticoolithus bradyi.

Over millions of years, Antarctica was home to a variety of creatures, from dinosaurs to flying birds to marsupials mammals. Our material is “Green Antarctica” will help you get a glimpse of this wonderful world, disappeared after the arrival of the glaciers.

Sergey Knee High

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