The nose of PNAS mammals comes from the jaws of reptiles

The traditional scientific understanding of facial evolution is that the jaws of mammals and reptiles develop in almost the same way

"Existing tetrapod fossils, whether they are the ancestors of reptiles or mammals, have the same number of upper jaw bones

Higashiyama of Professor Hiroki Kurihara’s laboratory and his colleagues designed experiments to track the facial development of embryos of different species, including birds (chickens), reptiles (geckos), and mammals (rats)

Using this new perspective of cell experiments, the researchers then examined the fossil specimens

As the ancestors of the species accumulated more physical and genetic differences, the anterior jaw bone of the upper jaw tip of reptiles became smaller and migrated upward, while the septal bone behind it became larger and moved forward, becoming the tip of mammalian jaws

The separation of the nose and chin gives mammals a unique "smell" ability.

Higashiyama said: "This discovery is a key innovation in the evolution of human and other mammals' sports noses, which helps mammals have a highly sensitive sense of smell

Differentiating and recognizing so many smells may also help mammals develop larger and more complex brains than earlier ancestor species

Recent studies have provided physical evidence of the evolutionary transition of the anterior and mid-maxillary jaws, but separate studies are needed to determine the genetic cause

"Now we know the composition of facial protrusion and embryonic development of many species, so we can compare the facial development disorders of chickens or frogs with humans

Mice is currently the only animal model to study cleft lip and palate

Hiroki Higashiyama, Daisuke Koyabu, Tatsuya Hirasawa, Ingmar Werneburg, Shigeru Kuratani, Hiroki Kurihara.