A question that has baffled scientists for decades about who came before the other, the chicken or the egg, and although many were taking this question with humor, scientists took the issue seriously and conducted experiments to finally answer that dilemma!
Scientists have found that the ancestors of modern birds and reptiles may have been born without eggs in the first place.
Researchers from the University of Bristol in the UK and Nanjing University in China noted that some species that lay eggs could have evolved from ancestors that were alive or gave birth to young, and species could mutate in both during the evolutionary process.
Therefore, they began to study 51 fossils and 29 living species, which can be classified as either eggs or newborns, especially since modern birds, crocodiles and turtles lay eggs when the embryo inside them is still at a very early stage of development, and continues to develop outside the mother and hatch later. According to the British newspaper, The Times.
Extended embryo retention
Mammals retain their embryos internally, known as extended embryo retention, or EER, allowing them to develop inside the mother before she is born at a young age.
While lizards and snakes also tend to keep their embryos internally for a longer period, after that they usually continue to lay eggs, but some of them can give birth to live young.
Previous studies indicated that early forms of mammals, lizards, crocodiles and birds, which fall under the so-called amniotes, lacked the ability to keep their embryos internally.
Since the age of dinosaurs
However, the new study, published in the journal Nature Ecology & Evolution, found that all branches of the evolutionary tree of amniotes, including crocodiles and modern egg-laying birds, had ancestors that kept the embryo inside for a longer period before reproduction.
In turn, Professor Michael Benton from the School of Earth Sciences in Bristol said, “The natural answer to the question of the chicken and the egg is that it is clear that the egg came first, because every bird lays an egg, and this has been since Archeopteryx, that is, the flying dinosaur that lived about 150 million years ago.”
Dinosaurs (Shutterstock)
He added, “We can be pretty sure that many dinosaurs laid eggs during their evolution. Our research does not change that, but it does change our assumption that the hard-shelled egg was a very early juvenile, and there was even greater diversity in reproductive patterns, especially the ability On Keeping the Young Through EER”, i.e. extended embryo retention.
Now tell us in the comments, did this study surprise you, or do you think it answered the “puzzling question” logically?
