Scientists finally answer the question: “Which came first, the chicken or the egg?” | Science

What came first, the egg or the chicken? It is an eternal question that mankind has been trying to solve for a long time from science. Now, a recent study sheds light on a possible answer.

To unravel the nature of chickens and eggs, scientists often turn to their ancestors: the dinosaurs. However, recently published in the journal Natural Ecology and Evolution He goes too far back to solve this mystery.

The study reveals that the first amniotes – the ancestors of terrestrial vertebrates – provided offspring through extended embryonic retention (EER). It means developed within the offspring In the wombIt occurred both viviparous (embryo alone) and oviparous (within eggs).

The discovery was made from an analysis of a fetus choristodere Ikechosaurussp, one of those that lived on the planet between 168 and 120 million years ago. The calf was inside a Soft shell egg – Parchment is called shell.

“A high degree of ossification of the skeleton indicates that The unhatched embryo was late in development”, the document says. The specimen’s skull is well-sculpted and has sharp teeth that are detailed.

So, the chicken or the egg?

The study indicates that interbreeding occurred once in the ancestors of ammonites and marine reptiles. BellyOne of the study authors noted this does not mean that Chicken It came before the egg.

“The first EggBecause chicken is one of many birds [que aparecieron antes de ella]. “Of course, all birds, as we know, lay hard-shelled eggs,” said scientist Michael Benton. National Public Radio (NPR).

According to Benton, it may be the first Hard shell egg It was laid by one of those ancestral birds. Therefore, the first chicken must hatch from one of those eggs.

“So a quick answer is that the egg comes first. However, if you dig further into time, our research suggests that’s not the whole story.”

But what is that story worth knowing? The authors speculate that the first archosaurs (a group that includes dinosaurs, reptiles and birds) carried their young inside their wombs. Soft shell eggs or embryosUntil they are ready for birth.

Later, they adapted to the terrestrial environment, allowing hard-shelled eggs to be laid early in embryo development.

Today, only archosaurs are alive Birds and crocodiles (order of crocodiles and their relatives), which appeared after millions of years of evolution. According to the study, all these species lay hard eggs.

Additional information related to the topic:

What is Coristodere Ikegosaurussp.

The specimen used for testing was a Corystodor Ikegosaurus sp. Choristoderes are ancient aquatic reptiles that lived in Laurasia from the Middle Jurassic to Early Miocene, 168 to 120 million years ago. The shape of these individuals is similar to that of the present-day gharials, a species of the order Crocodylia.

What are Archosaurs?

Los archosaurs (Archosauria) includes a group of animals common ancestor Birds and crocodiles (including alligators and lizards). Because they dominated most of the terrestrial vertebrate kingdom during the Mesozoic (comprising the Triassic, Jurassic, and Cretaceous periods), they are also known by scientists as the “ruling reptiles.”

Evolutionary tree of birds

Scientists discovered that Aves formed from Dinosaurs Through analysis of a specimen of Archeopteryx, a link between feathered dinosaurs and modern birds, from the late Jurassic.

Like modern birds, Archeopteryx It had feathers on its arms and tail; However, it was distinguished by a long tail with teeth and bone, notes the University of California, Berkeley.