Fossils of Romundina, Jawed Fish Provide Insight into Face evolved
There are two categories of Vertebrates, backboned animals, which are jawless and jawed. The number species of jawed vertebrates is more than 50,000 and also includes humans. On the other hand, there are two jawless vertebrates in existence today and these are lampreys and hagfishes.
Scientists have been keen to know about the evolution of the face. A small, primitive armored fish called Romundina swam the sea 415 million years ago. The remains of the fish were discovered in the Canadian Arctic, which provides some revealing answers.
Romundina along with Swedish and French researchers have described in the study, published in the journal Nature on Wednesday, that jawed vertebrates evolved from jawless ones. Micron resolution X-ray imaging technique was used by a team of researchers to study the reason behind evolution.
In embryos of jawless vertebrates, blocks of tissue grow forward on either side of the brain. These further meet in the midline at the front to make a big upper lip surrounding a single midline 'nostril', which lies just in front of the eyes.
However, in case of jawed vertebrates, the same tissue grows forward in the midline under the brain, pushing between the left and right nasal sacs which open individually to the outside.
This is the reason that our face has two nostrils instead of a single big hole in the middle. Also, the front part of the brain is much longer in jawed vertebrates, which is the reason that our nose is positioned at the front of the face instead of far back between our eyes.
The scientists studied the skull of Romundina, an early armored jawed fish, from arctic Canada. Vincent Dupret of Uppsala University, one of two lead authors of the study, says, "This skull is a mix of primitive and modern features, making it an invaluable intermediate fossil between jawless and jawed vertebrates".
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