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Gli squali fossili

Isurolamna

CAPPETTA 1976
Extinct mackerel shark
Upper Paleocene - Lower Eocene
Ordine Famiglia
Lamniformes BERG 1958 Lamnidae MÜLLER & HENLE 1838

Cappetta erected this genus for a dentition displaying a combination of characteristics. The lower anteriors lack cusplets and have thick, but mesio-distally compressed, roots with nearly vertical lateral margins and a straight cusp. The lingual protuberance bears an elliptical foramen. The upper anteriors have roots that are more slender & elongated, and may bear a reduced mesial cusplet. The lateral teeth have a pair of triangular, labio-lingually compressed cusplets and root lobes, which are elongated but thick, and obtusely divergent.

Isurolamna inflata (LERICHE 1905) has been reported from the Upper Paleocene (Thanetian) and/or Lower Eocene (Ypresian) of North Africa, Europe and North America. Isurolamna affinis (CASIER 1946) has been previously reported from the Ypresian of Europe.
 

Fig. 1 - Isurolamna affinis
From left to right, 10.0 x 10.0, 10.0 x 9.0 and 7.3 x 9.3 mm
Potapaco Member, Nanjemoy Formation, Virginia (Ypresian)
from the collection of Mike Folmer

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