Extinct Shortfin Mako
Isurus desori (Sismonda)

Age - Miocene  Commonality - Uncommon

Two species of mako have been reported from New Jersey; Isurus praecursor from the Eocene and Isurus desori from the Miocene, both belonging to the group of extinct narrow-toothed mako sharks. The teeth of Isurus desori are fairly large, averaging over an inch in length and reaching a maximum length of well over of 2 inches. When compared to other teeth from Monmouth County these teeth are relatively robust and except for juveniles have no cusplets. A nutrient grove is lacking, or a best shows as a weak depression. On specimens that are not too stream worn nutrient pores may be present, these may form what looks like a single opening due to clustering and/or stream wear.  The lateral teeth of Isurus desori and Isurus praecursor are almost indistinguishable. Large sand tigers that are missing their cusplets may also be mistaken for makos.    



Mako, Isurus desori

Anterior and lateral teeth of Isurus desori.


Isurus desori

The two largest anterior teeth I have found to date. both teeth are just over two inches in length.
 Most anterior teeth have two complete cutting edges, some specimens
may have an incomplete cutting edge on the distal side.

See the cutting edge comparison page


Lateral teeth if Isurus desori. The roots on the lateral
teeth are large with a "block like" appearance. Except as juveniles,
the lateral teeth lack cusplets.



Nutrient pores forming a single hole


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