Some dinosaurs hatched eggs like birds 74 million years ago

Dinosaurs, although they have much in common withmodern birds, it is generally accepted that they did not incubate eggs, but instead buried them in the ground, as cold-blooded reptiles do today. For example, crocodiles and turtles do this. However, a recent study showed that some dinosaurs did incubate their eggs. One of them was Troodon, or Stenonychosaurus, which lived from 74 to 66 million years ago. Moreover, scientists have found that these dinosaurs built common nests, where they laid eggs and then hatched them at once by several females. thanks to this, the dinosaurs were warmer, in addition, apparently, they looked after the eggs together.

Some non-avian dinosaurs hatched eggs like birds

Troodon bird-like dinosaur

Stenonychosaurus was a smallpredatory (more correctly, even omnivorous) dinosaur, which was a relative of modern birds. It belonged to the suborder of theropods, like the other bird-like dinosaur Microraptor, which we talked about earlier. Troodon was covered with feathers and generally looked very much like a bird, although it was still a reptile, that is, it did not belong to avian dinosaurs.

It must be said that scientists have previously knownthat some theropods incubated eggs. Recall that theropods are a group of bipedal carnivorous dinosaurs, which include the well-known tyrannosaurus rex and velociraptor. The first theropod dinosaur that incubated eggs was discovered a few years ago, as reported in the journal Science Bulletin.

Scientists believe that, among other things, Troodon had a developed intellect.

Теперь же выяснилось, что и троодоны высиживали eggs, as they created nests and were warm-blooded. Moreover, they could independently regulate their body temperature. According to the researchers, the average body temperature of Troodon was 42 degrees Celsius.

However, when the animal encounteredlimited food or harsh weather, lowered the temperature to 29 degrees, which saved energy. This phenomenon is called heterothermy, and it occurs in modern birds. When the dinosaur had to sit on the eggs, they, on the contrary, raised the temperature.

Egg laying in birds and reptiles - what are the differences?

According to a study published injournal Proceedings of the National Academy of Sciences, the authors of the work studied the mineralization of the eggshell of Troodon eggs, and then compared with the eggs of modern birds and reptiles. They focused their attention on the content of calcite in the eggshell. This allowed them to determine the rate and temperature at which the eggs formed.

Birds lay more eggs than reptiles because their eggshells mineralize faster

As it turned out, in birds and reptiles, modelsmineralization was different. This is due to the fact that birds have only one ovary. The second disappeared in the course of evolution. Obviously, this allowed the birds to reduce their weight and make it easier to fly. But to make up for the lack of one ovary, birds have evolved the ability to quickly form eggshells. As a result, they produce many large eggs in one clutch.

Reptiles have two ovaries, since the weight for them is notmatter. However, the mineralization process is slower. Therefore, the number of eggs per clutch is more limited. However, both reptiles and birds are descendants of dinosaurs. This means that in dinosaurs, the mineralization model must be either one of the two, or somewhere in between, that is, have common features of both models.

Stenonychosaurs built common nests

What model of egg mineralization did Troodon have?Despite the fact that the dinosaur developed pronounced bird features, the mineralization of eggs occurred slowly, that is, like in reptiles. Therefore, in one clutch, the animal laid from four to six eggs. This suggests that Troodon was in the middle of an evolutionary development between birds and reptiles.

Troodon nests contain more eggs than a single female could lay

But what surprised scientists the most was thatTroodon nests discovered had many more eggs. One female dinosaur physically could not lay as many eggs in a reasonable time as paleontologists found in nests. Reasonable means the time during which the embryos do not die. From this, the researchers concluded that several females laid eggs in one nest at once. So they hatched eggs "company".

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Thus, the study containsseveral interesting discoveries. In particular, it sheds light on the transition from cold-bloodedness to warm-bloodedness. Scientists hope that they will be able to find out where and when this transition happened. I must say that recently there is more and more information about these extinct animals. For example, recently scientists managed to find out when dinosaurs began to spread across the Earth. This happened 230 million years ago.