Karpinskiprion

Karpinskiprion is an extinct genus of eugeneodontid holocephalan fish. Its type species is K. ivanovi, a species assigned to Campyloprion.

 Description 
One specimen of K. ivanovi recently discovered in the Volgograd Region of Russia is the most complete Karpinskiprion specimen ever found. It unambiguously demonstrates the coiled nature of these tooth whorls and presents information on their developmental stages.

During organogeny, cutting blades of the crown became reshaped, and basal spurs progressively elongated, forming a grater. Whorl growth in this genus occurred by addition of new crowns to the earlier mineralized base followed by later spur growth.

In contrast to consistently uniform cutting blades, spurs are often malformed and bear traces of growth interruption. Both sides of the outer coil of the tooth whorl bear lifetime wear facets. The youngest (lingual) crowns are as yet unaffected by wear. The best-preserved facets show parallel radially directed scratch marks.

The upper jaw dentition is unknown. However, it is suggested that the faceted areas are from interaction with the antagonistic dental structures here. Three possible hypotheses for this interaction are suggested here: (a) two opposing whorls acted as scissor blades, moving alternately from one side to another; (b) the lower tooth whorl fitted between paired parasymphyseal tooth whorls of the opposing jaw; or (c) the lower tooth whorl fitted into a dental pavement in the maxilla.

 Related pages 

 Pshekhagnathus
 Kenyaichthys

 References 
Category:Cartilaginous fish