Have you ever wondered if the birds are reptile? Did you know that the genealogical tree of reptiles is more varied and diverse than you can imagine?
Martin Stervanderevolutionary biologist and senior bird curator in National Museums ScotlandHe said, “I would say that any modern biologist would say, or should say that birds are reptile.”
But, according to, it was not always like that. Before the 1940s, the biologist was based on a system called Linnaean method to classify all life on Earth.
This approach was developed by Carl Linnaeus In the 1730s and works by grouping animals that have similar physical characteristics.
Linnaeus determined that all reptiles share two fundamental characteristics: have scales and are ectothermic or “cold -blooded“Which means they have to depend on external sources of heat to regulate their body temperature.
As the hot -blooded and abundant birds in penalties do not have these characteristics, “the birds were considered their own branch in the tree of life”Under the Linnaen system, he said Klara Widriafrom the Department of Vertebrate Zoology of the National Museum of Natural History of Smithsonian, in Washington, DC
The classification does not take into account something that can reveal much more about an organism: your genes.
From the 1940s, the ability to examine genetic material gave rise to a new type of classification, called phylogeny. The phylogenetic method groups or separates organisms based on amount of DNA they have in common.
It also allows scientists to buy compare organisms’ DNA to trace their evolutionary history and find ordinary ancestors.
According to this system, the organisms are grouped into “clados“Which are distinct branches in the phylogenetic tree that include all descendants of a more recent common ancestor.
For example, modern birds are grouped into the neornithes clad, because they arose from an ordinary ancestor Neornithine what It emerged 80 million years agobefore the extinction of Nonavian dinosaurs.
“The Clados are a nestled hierarchy“Widrig explained,“ if we retreat more along the branches of the tree of life, we find that [os Neornithes] also belong to the most inclusive clad Theropoda“, A group of dinosaurs with two legs and mostly carnivores who, in turn, descend from clad Dinosauria.
Even in the era of dinosaurs, the characteristics that defined the scaly reptiles and birds were not so different.
The investigation suggests that Some dinosaurs were warm -blooded and that Some nanvian dinosaurs had feathers.
However, later, it was known that the birds that looked exactly with the modern birds were already on earth next to their dinosaurs 66 million years ago.
One of them was the “Wonder Chicken” (Asteriornis)a fossil that was described in 2020 by a team that included Widrig.
The offspring of the birds of Theropods e Dinosauria It is what makes them dinosaurs.
However, the Dinosauriatogether with the crocodilianos and other strains like pterossaurosare inserted in another clad, called Archosauria.
This clade, in turn, shares an ancestor with a group called Lepidosauriawhich gave rise to all modern lizards, snakes and Tuatara. This common ancestor was a creature called sauropsida that emerged about 315 million years ago and gave rise to the same name.
Sauropsida was one of two lineages that branched from the amniotasthe other being the group that evolved into the class Mammalia. Sauropsida, however, became synonymous with class “Reptile“Because within your network of clads, all reptiles – both alive and extinct – are inserted.
Why don’t birds look like other reptiles?
The links between birds and their most castly relatives could have been easier to understand If there had been no mass extinction event for 66 million years.
“The reason poultry seems so strange, compared to the rest of the reptiles we have alive today is because all the intermediate evolutionary phases are extinct, so we don’t have to compare them.”
When it destroyed much of life on earth, he obliterated entire sections of the lineage Archosauria reptiles, leaving behind only crocodiles and some Avian dinosaurs.
Without this emptiness in the tree of life, evolution could have introduced relatives into the modern era that would have made Reptilian roots of the most immediately clear birds.
Instead, currently the crocodiles are living relatives closer to birdsalthough they are far away from the phylogenetic tree.
In human terms, “if all nonhuman primates suddenly extinguished the Our closest living relatives would be the rodents and the rabbits“Said Widrig. They would be the closest to us in the remaining branches of the tree of life, and our shared mammired ancestry could be harder to accept.
If still It seems strange to think of birds as reptilesThis may be partly due to these Linnean roots, which continue to shape our colloquial understanding of what a reptile is.
Only around the 1940s do genetic tests effectively clarified the position of birds“Stervander said. “Before that, people had referred to reptiles almost two centuries ago. I think that’s why it has been some reluctance in redefining what we call reptile“.
Currently, science is changing this, revealing Unexpected links in the tree of life – and opening New horizons about reptiles with penalties and flyers.
Teresa Oliveira Campos, Zap //
