Japanese scientists discovered that mammalian noses come from reptile jaws

Hiroki Higashiyama, the study's lead author, and his colleagues conducted experiments to track the development

faces in embryos of various species, including birds,reptiles and mammals. For the study, they took a group of cells on the facial protrusions of embryos. The researchers stained the cells to track their movement and growth. In the study, they discovered that a group of cells, the frontonasal protuberance, forms the tip of the jaw in reptiles but becomes the prominent nose in mammals. The tips of the jaws of mammals are formed from a separate group of cells and are called the maxillary protuberance.

"In the fossils of four-legged animals, likeancestors of reptiles and mammals - the same number of bones of the upper jaw. The bones look the same, but now we have learned to track the cellular development of the embryos in order to better study them, ”explained Higashiyama.

Researchers say facial bonesmammals such as the Australian platypus and the echidna are examples of transitional bone structures from the evolutionarily older reptile model to the younger one in mammals. The separation of the nose and jaw allows the animals to sniff, using their muscles to flare their nostrils and inhale deeply. Smell recognition may have also helped mammals develop larger and more complex brains than their ancestors.

"The discovery is a key innovation in the evolution of the nose of mammals, which contributes to the development of a highly sensitive sense of smell," - said Higashiyama.

The study was the first in the evolution of facial structure using cellular studies comparing multiple embryos of different species.

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