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The evolution of an ancient fish might be able to explain the evolution of faces in vertebrates including humans as well. 

A new study has presented new fossil evidences that depict the origins of the face. With the help of micron resolution X-ray imaging, researchers showed how a series of fossils documented the step-by-step evolution of the face during the evolutionary transition from jawless vertebrates to the ones containing it. 

The fish being considered in the research is the 410 million-year-old armored fish called Romundina. According to scientists, Romundina played an important role as it is in the evolutionary position as a transitional species. 

"In embryos of jawless vertebrates, blocks of tissue grow forward on either side of the brain, meeting in the midline at the front to create a big upper lip surrounding a single midline 'nostril' that lies just in front of the eyes," the researchers said in the press release.

"In jawed vertebrates, this same tissue grows forward in the midline under the brain, pushing between the left and right nasal sacs which open separately to the outside. This is why our face has two nostrils rather than a single big hole in the middle. The front part of the brain is also much longer in jawed vertebrates, with the result that our nose is positioned at the front of the face rather than far back between our eyes."

The ancient fish also represented an intermediary phase in the facial evolution, researchers said. It had a separate right and left nostrils sitting back behind lips like a vertebrate without jaws. 

"This skull is a mix of primitive and modern features, making it an invaluable intermediate fossil between jawless and jawed vertebrates," said Vincent Dupret of Uppsala University, one of two lead authors of the study, in the press release. 

"In effect, Romundina has the construction of a jawed vertebrate but the proportions of a jawless one," said Uppsala University's Per Ahlberg, the study's other lead author. "This shows us that the organization of the major tissue blocks was the first thing to change, and that the shape of the head caught up afterwards," he added in the press release. 

The study is published in the journal Nature.