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THE SAWFISH
Ischyrhiza mira (Leidy)
Age Cretaceous - Occurrence Common
The sawfish is not a shark but
a
skate. These somewhat common “teeth” that are collected in the
streams of NJ are really the rostral spines that lined the elongated and
flattened bill of the skate. These spines are unique and not easily
confused with any other species. Not nearly as popular with
collectors are the small oral teeth
of Ischyrhiza mira. Normally less than 1/4 of an inch across,
these teeth will commonly fall through the
standard 1/4 inch mesh screen.
Author's note: Because the rostral spines of I. mira can
be identified from the root alone I've listed their occurrence as
common. In reality, these spines are very prone to damage and complete
specimens are uncommon.
A pristine rostral spine. Notice the distinct shape of the root and the
change in color at the tip of the blade
The rostral spines of the sawfish can get rather large and come in some
unusual shapes. The distinctive root makes this an easy tooth to ID.
Scale 1 inch
The enamel portion of the rostral spine is very prone
to snapping off.
Broken, but still identifiable, this picture represents the general
condition
the vast majority of
Ischyrhiza mira rostral
spines are found in.
The oral teeth of Ischyrhiza mira are small, normally less than
1/4
of an inch across and will fall through the standard 1/4 inch mesh
screen
The oral teeth have a deep nutrient grove in the root.
An assortment of oral teeth perched atop a US quarter.
(24mm)
Rostal spines
Modern day sawfish
rostrum
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