The closest relatives of dinosaurs are modern birds and crocodiles. Among these feathered creatures and toothy reptiles there are no viviparous species and they all lay their eggs. Consequently, dinosaurs that lived millions of years ago also set up nests and hatched eggs — but what were they? Previously, scientists were sure that the dinosaur eggs were covered with a hard shell, just like the chickens and ostriches living today. However, during one of the scientific works, the researchers found that dinosaur cubs developed inside soft sacs. This discovery greatly changed the ideas of scientists about the development and life of ancient creatures.
Live birth - This is a way of reproducing offspring, in which cubs develop inside the mother. At egg production the cubs develop inside the eggs and after a certain period of time go out of them.
The fact that the eggs of ancient creatures were deprived of a hard shell is indicated by the fossilized remains of eggs of two dinosaur species at once.
About 75 million years ago, inmodern Mongolia, lived the so-called protoceratops (Protoceratops) - herbivorous dinosaurs the size of a small sheep. In the course of numerous studies, scientists were able to find many places for laying eggs of these creatures. But one of them attracted especially much attention - the remains of 12 cubs were found in the nest, and six of them had a well-preserved skeleton.
Researchers conducted a chemical analysis.petrified eggs and found in them the same substances that make up the inner layer of eggs of modern birds and crocodiles. But no traces of the minerals from which the hard shell is formed were found. Although, following the logic, the hard part of the eggs should have been preserved much better than the soft inner layer. It was suggested that the dinosaur eggs were soft and weakly protected.
This is also interesting: How long did it take for dinosaurs to hatch from an egg
The fidelity of the theory was further reinforced,when the researchers studied the remains of the eggs of the Mussaurus (Mussaurus). These six-meter dinosaurs were also herbivorous, but they lived about 227 million years ago and in a completely different place - in the territory of modern Argentina. After studying the chemical composition of the remains, the researchers again found only traces of a soft inner shell. The presence of a hard shell was not even a hint.
Secrets of the ancient world
But how can we explain what was previously researchersmanaged to find the remains of solid dinosaur eggs? Researchers believe that shell hardening occurred during evolution. Initially, the eggs were soft and poorly protected - this put the dinosaur population at risk. Therefore, over millions of years, the eggs of ancient creatures began to harden and the shell provided protection from both mechanical damage and sunlight.
This is probably why the eggs of modern hens andcrocodiles have a hard shell. It is strong enough to protect developing cubs from external influences. But the shell is also fragile, so that developed creatures can get out of them and start a full life.
The new discovery was told in the scientificNature magazine. It is worth noting that even evidence that ancient creatures laid eggs without a hard shell was found relatively recently. In 2011, something similar to fossilized potatoes was found on the territory of cold Antarctica. The fact that this object all this time was an egg of the ancient Mosasaurus (Mosasaurus), the researchers realized only in 2018. These creatures lived under water and, as it turned out, also laid soft eggs. You can read more about the discovery of the researchers in this material, but at the end of this article it must be said that yes - the eggs of some dinosaurs really were shellless.