THE SHARKS

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Extinct Early Mako
Isurus praecursor (Leriche)
 

Age - Eocene  Commonality - Uncommon

One of several species of mako shark teeth found in New Jersey, Isurus praecursor is the earliest known mako and is restricted to the Eocene. Size is between ½ to 1 ½ inches long, the teeth of I. praecursor, when compared to the other makos has a relatively short stout crown. 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. Kent mentions that the “lateral teeth of I. praecursor are nearly indistinguishable from those of the later Isurus species”.¹ Most reference material notes the similarity between these two species and suggests using stratigraphic origin as an aid to identification. Large sand tigers that are missing their cusplets may be mistaken for makos.
  


 

Isurus praecursor

Anterior Isurus praecursor.
 


 

Isurus praecursor

I. praecursor anterior lateral (top) and lateral (bottom).

 


 

One of my larger makos.
 


 

Small cusplets may be present on the lateral teeth.
 


 

Nutrient pore on an anterior tooth.


 


Miscellaneous pictures

 


¹ Kent, W.B, 1994. Fossil Sharks of the Chesapeake Bay Region, Egan Rees & Boyd, Inc., 57pp.
 

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