Fish fossil confirms origin of nostrils

New Scientist ^ | 11.04.04 | Bob Holmes

[4kevin]

Land vertebrates can breathe through their noses thanks to an anatomical rearrangement of fish-style nostrils. That same rearrangement may explain why cleft lips and cleft palates are common birth defects in humans.

The nasal passages of land vertebrates differ dramatically from their fish ancestors. In fishes, the nose is independent of the mouth and throat. Water enters the nasal sac through one pair of nostrils and exits through a second pair.

By contrast, land vertebrates - technically known as tetrapods, because of their four limbs - have nasal passages that open to the outside world through a pair of external nostrils, and to the throat through a pair of internal nostrils or choanae.

Many biologists suspect the choanae evolved from one pair of fish nostrils that migrated over millions of years to a new position inside the throat. To do that, however, the nostrils would have had to cross through the line of teeth at some point, a move that sceptics regarded as unlikely.

[4kevin]

I thought something smelled fishy about my ex-wifes ancestors ;)

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[T'wit]

Fingers evolved to pick nostrils.

[boris]

Thoughts of Henry Waxman arise...

[SunkenCiv]

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