Lamprey-like gills in a gnathostome-related Devonian jawless vertebrate

Article Abstract:

The first direct evidence for the position of the gill filaments is presented supported by gill rays enclosed by gill pouches in a 370-million year-old jawless vertebrate, Endeiolepis, from the Late Devonian fossil fish site of Miguasha, Quebec, Canada. This demonstrates that pouches enclosing the gills are primitive for vertebrates, but subsequently lost in jawed vertebrates.

Canada, Discovery and exploration, Fossils, Gills, Agnatha

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Wandering nostrils

Article Abstract:

Choanae known as 'internal nostrils' that form the passage between the nasal cavity and throat that are used for breathing when the mouth is closed, have been the subject of much argument regarding the way they originated in the tetrapods. It is suggested that tetrapod choanae are posterior nostrils whose position is not homologous in the palate.

Nasal fossa

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Born-again hagfishes

Article Abstract:

Studies conducted report the first early embryos from hagfishes found since 1930 and describe their gene-expression patterns in them. The findings show that the neural-crest cells of hagfishes delaminate and migrate like those of all other living vertebrates, which classify hagfishes as conventional vertebrates.

Genetic aspects, Gene expression, Hagfishes

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