THE SHARKS

Extinct Mackerel Shark
Protolamna borodini (Cappetta & Case)
aka Cretodus borodini

Age - Cretaceous  Commonality - Uncommon

Protolamna borodini is one of three species found in New Jersey that is locally referred to as “the porbeagles”. The more generally accepted common name is mackerel shark. The teeth of P. borodini are small, averaging less than ¼ inch in length with a maximum size of just under ½ inch. This species has a deep “U” shaped root, a large single triangular cusplet on each shoulder and strong basal wrinkles on the labial face of the crown. There is a strong lingual protuberance, which appears quite exaggerated. Because of their small size most specimens will fall through the standard ¼ inch screen. The large cusplets and root lobes seem particularly prone to damage.

Protolamna borodini tooth measuring less than 1/4 inch.
A distinct characteristic of this species is the exaggerated
  lingual protuberance.
Monmouth County, NJ.
 

Basal wrinkles on the labial face.
Occasionally these wrinkles or folds may also be present
on the lingual surface of the crown.
Note how large the cusplets are in relation to the crown.
 

Specimen of Protolamna borodini with basal wrinkles on the
lingual surface of the crown.
This seems to occur more often in the very small teeth.

These teeth are small, averaging around 1/4 inch in length.
The root can account for about 1/2 the length of the tooth.
 

Because of their small size these teeth will normally fall through
the standard 1/4 mesh screen normally used in the streams of
Monmouth County.
This is the only specimen I have found using the common 1/4
inch mesh screen.

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