Edaphodon

Edaphodon was a prehistoric chimaeriforme fish genus belonging to the family callorhinchidae. Edaphodon was a type of rabbitfish, a cartilaginous fish related to sharks and rays, and indeed some rabbitfishes are still alive today. Edaphodon has under fifteen known species, all of which are extinct. Chimaeriformes first appeared during the Devonian period around 415 to 360 million years ago, but this particular genus was most prominent during the Late Cretaceous. All Edaphodon species were situated in the Northern Hemisphere, apart from E. kawai, which was recently discovered in the Chatham Islands near New Zealand. This shows that the range of Edaphodon reached further than was previously thought.

Description

Like most other chimaeriformes, Edaphodon is known mainly from poorly preserved specimens; this is due to Edaphodon being part of the chondrichthyes group, which are made of cartilaginous materials. Thus only a few spine and tooth fragments remain in most cases. E. kawai has been compared to another prehistoric cartilaginous fish, Ischyodus, which closely resembles the rabbitfish Chimaera monstrosa. Whether the E. kawai remains are actually Ischyodus remains is yet to be seen.

Edaphodon is very similar to other rabbitfishes in appearance - it had dark scales, and fed using "grinding plates" of teeth that didn't regrow, unlike sharks. It is assumed that it laid eggs in a leathery pouch like other rabbitfish, but no occurrences of this have been recorded. Edaphodon had a sloping head and a mouth on its underside, allowing it to graze along the bottom of the ocean like a land-dwelling herbivore.

Species

Edaphodon has numerous species, all of which are extinct:

• Edaphodon agassizi - Buckland, 1835
• Edaphodon antwerpiensis - Leriche, 1926
• Edaphodon bucklandi - Agassiz, 1843
• Edaphodon eyrensis - Long, 1985
• Edaphodon kawai - Consoli, 2006
• Edaphodon laqueatus - Leidy, 1873
• Edaphodon leptognathus - (has not been formally classified) Agassiz
• Edaphodon minor
• Edaphodon mirabilis - (has not been formally classified)
• Edaphodon mirificus - Leidy, 1856
• Edaphodon sedgwicki
• Edaphodon smocki - Cope
• Edaphodon stenobryus - Cope
• Edaphodon tripartitus - Cope

References

• Consoli, C.P. (December, 2006). EDAPHODON KAWAI, SP. NOV. (CHONDRICHTHYES: HOLOCEPHALI): A LATE CRETACEOUS CHIMAEROID FROM THE CHATHAM ISLANDS, SOUTHWEST PACIFIC. Journal of Vertebrate Paleontology 26(4):801–805.

External links

• Froese, Rainer, and Daniel Pauly, eds. (2006). "Chimaeriformes" in FishBase. January 2006 version.