Researchers from the School of Geosciences at the University of Bristol in the UK have decided to put an end to the long-standing debate about which actually came first – the chicken or the egg. The corresponding study was published in the scientific journal Nature Ecology and Evolution.
Scientists studied 51 fossils and 29 living species, which are classified as oviparous and viviparous.
It turned out that the most distant ancestors of the chicken are reptiles that lived millions of years before the advent of dinosaurs. And these same reptiles did not lay eggs.
As Professor Michael Benton explained, before the advent of the amniotes (a group of vertebrates that undergo embryonic or intrauterine development inside the amnion – a protective shell inside the egg), the first tetrapods to develop limbs from fish fins were generally amphibians. They lived in or near water to feed and reproduce, much like modern amphibians such as frogs and salamanders.
When amniotes appeared 320 million years ago, they were able to break away from the water. However, the amniotic egg was the key in which the developing reptile was protected from drying out in warm climates and allowed the parents to move away from the water and explore the land.
Thus, it turns out that at first there was still a chicken (or a reptile), and then an egg appeared. In other words, reptiles evolved into birds, which then learned to lay eggs.
Source: Rosbalt
Mario Twitchell is an accomplished author and journalist, known for his insightful and thought-provoking writing on a wide range of topics including general and opinion. He currently works as a writer at 247 news agency, where he has established himself as a respected voice in the industry.
