Description: The only skate represented at Big Brook is that of Ischyrhiza mira.  Two different types of teeth can be recovered for this sawfish, as well as calcified cartilage sections and possibly vertebral centra.

Many rostral spines similar to teeth lined the elongated and flattened bill.  The blades of the rostral spines are long and flattened and are very similar in shape to the main cusp of a sharks tooth.  The roots are very robust and have a square outline when viewed from the bottom.  The root is split one quarter of the distance up the root with a deep groove that is on the same plain as the flattened blade.  The bottoms of the roots are marked with grooves running perpendicular to the deep groove.  The rostral spines are generally 1 to 4 cm (about .25 to 1.5 in.) long.

This skate had diminutive oral teeth that lined its rather small mouth.  The main cusp of the oral teeth is marked with a protruding downward pointing cusplet on the back of the tooth, while the front side possesses a thick apron.  Their roots are also bilateral and marked with deep grooves along the bottom of the tooth.  These oral teeth are rarer than the rostral spines, a fact related to their very small size, around 5mm (about .18 in.) long.  These teeth will fall through the commonly used inch screens.  Small mesh screens should be used to recover these teeth.

Various calcified cartilage sections, possible from the bill and loosely attributable to
Ischyrhiza, also occur but are hard to positively identify.  They are irregular shaped sections that, from the top, look like grouped elliptical cylinders and the back is similar looking to bone.

Vertebral centra attributable to the sawfish probably also occur but are no doubt too similar to other batoids to be able to tell the difference between them.

Commonality: The complete rostral spines from the sawfish are somewhat common while the cartilage sections are not as common.  The teeth are rarely recovered due to their small size.

Similar Fossils: The rostral spines are not easily confused with any other locality teeth except when the roots are broken off.  In this case, they could appear to be goblin or porbeagle shark teeth.  The rostral spines are not curved and lack the striations of the goblin but they have a lens shaped cross section that differentiates it from the porbeagles.  The oral teeth can be confused only with the teeth of the angel shark.  Sawfish oral teeth are more pyramid shaped while the teeth of the angel shark are more pointed and less complex appearing.

Size: This sawfish is rather large about 2 to 3 meters (about 7 to 10 feet) not including the long bill.

Notes: Skates are primitive but are still around today.  It is believed that the skates are the evolutionary link between sharks and the rays.  They are flattened but not as flattened as the rays are.  The bill that was armed with "teeth" was used in catching prey.  It would swim through a school of fish and impale the fish on the "teeth" as it waved its' bill back and forth.  It would then dislodge the fish and eat them.  The term "fish" in sawfish is misleading.  The sawfish is not a true bony fish and has a cartilaginous skeleton and the teeth and the rostral spines are the only bone.  It is closer related to the sharks and rays.  Their close relatives were widespread worldwide during the Cretaceous and are still alive today.
Sawfish
Ischyrhiza mira Leidy
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Typical rostral teeth
Typical rostral tooth
Side view
Large rostral tooth base
a. Front view  b. Side view
Rostral bill cartilage section
Typical rostral tooth
a. Side view  b. Front view c. Bottom view
Oral Tooth
a. Back side b. Front side
Large rostral tooth
a. Front view  b. Side view