Eoptolamna, Kriwet & Klug & Canudo & Cuenca-Bescos, 2008

Kriwet, Jürgen, Klug, Stefanie, Canudo, José I. & Cuenca-Bescos, Gloria, 2008, A new Early Cretaceous lamniform shark (Chondrichthyes, Neoselachii), Zoological Journal of the Linnean Society 154 (2), pp. 278-290 : 280

GENUS EOPTOLAMNA GEN. NOV.

Derivation of name: From the Greek words: ‘eos’, meaning ‘dawn, early’; ‘adruptos’, meaning ‘tearing’; and ‘ Lamna ’, meaning ‘modern lamniform shark’, in allusion to the early occurrence and tearing-type dentition of this lamniform.

Type species: Eoptolamna eccentrolopha gen. et sp. nov.

Generic diagnosis: Eoptolamnids with the following characteristics: tooth crown faces with distinct vertical median crest extending from cusp–root junction almost to apex; few additional shorter and flexuous ridges present; well-developed lateral cusplets broadly united with main cusp, stronger inclined lingually than main cusp, and in front of labial cusp plane in profile view; lingual face of main cusp strongly cambered; cutting edges well developed and continuous; labial basal sledge smooth, delineating a short and narrow concavity; root high and coalescing in upper parts, free in lower part; lingual protuberance well developed, but low; nutritive groove narrow and marked in teeth of juveniles, more faint and almost completely closed in adults.

Differential diagnosis: The teeth of Eoptolamna gen. nov. distinctly differ from all other lamniforms in the presence of a faint, almost completely closed nutritive groove in the teeth of adult individuals, which is marked in juveniles.