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Fossils from Monmouth County, New Jersey

Sawfish (Ischyrhiza mira)

Age – Late Cretaceous; Commonality – Rostrals: Less Common, Oral teeth: Uncommon (when using a fine meshed screen), Vertebrae: Very Uncommon, Potential dermal denticles: Rare; Size – Rostrals: ½-2+ inches, Oral teeth: 3-6 millimeters,  Vertebrae: ½ – 2 ½ inches, Potential denticles: ½ inch

This was a large sawfish reaching about 8 ft. in length. Unlike modern sawfish (Pristids and Anoxypristids), which have their rostrals growing continuously directly from their rostrums, Ischyrhiza rostrals were attached to the rostrum with a root base. The rostrum was used to hunt fish. The oral teeth were shed and replaced (unlike the rostrals) and were used by the sawfish to devour the prey. The rostrals have a bilobate root which has ridges on the very base. The crown is smooth (sometimes has faint growth cracks) with two carinae on opposite sides and tapers to a point, which is usually white in color. The oral teeth have a bilobate root (with the root lobes looking like isosceles triangles when the tooth is viewed in basal view) which possesses a nutrient pore in the center. The crown is relatively large and broad. It has an apron on the labial side and small enameled shoulders. The crown apex is fairly robust, although it does come to a point. The potential dermal denticles are referred to as “Peyeria sp.,” but are most likely from I. mira. They are described in detail on the “Ray Dermal Denticles” page.

Rostral Spines

Dorsal View

Ventral View

Anterior View

Posterior View

Oblique View

Nice rostral spine. Most have some type of wear or breakage.

Ventral View

Dorsal View

Anterior View

Posterior View

Oblique View

This one has a neat curve in its crown.

Dorsal View

Ventral View

Sawfish (Ischyrhiza mira) Rostral spine, Cretaceous, New Jersey

Anterior View

Posterior View

Basal View

Oblique View

Pristine rostral (37/32 inches). It is hard to come by such nice ones.

Dorsal View

Ventral View

Anterior View

Posterior View

Oblique View

A massive rostral at 15/8 inches. It is almost as large as they get in NJ.

Dorsal View

Ventral View

Anterior View

Posterior View

Oblique View

This would have been another large rostral.

Dorsal View

Ventral View

Anterior View

Posterior View

This one has an interesting sickly shape.

Dorsal View

Ventral View

Anterior View

Posterior View

Oblique View

This one is a posterior rostral. Posteriors are more stout and more angled posteriorly.

Dorsal View

Ventral View

Anterior View

Posterior View

This small spine is likely from a juvenile.

Dorsal View

Ventral View

Anterior View

Posterior View

This one shows an interesting post-mortem wear pattern. The margin in between the root and the crown is worn down. This one was likely in the process of splitting into a root and a crown. Most finds actually consist of just the root or crown.

Ventral View

Dorsal View

Anterior View

Posterior View

This partial spine is encrusted with matrix.

Dorsal View

Ventral View

Anterior View

Posterior View

Basal View

The ridges on the root stand out really well on this specimen.

Oral Teeth

Occlusal View

Basal View

Lingual View

Labial View

Sawfish (Ischyrhiza mira) Oral tooth, Cretaceous, New Jersey

Profile View

The oral teeth are very distinct in shape. This one is an anterior.

Occlusal View

Basal View

Lingual View

Lingual View

Labial View

Profile View

Another anterior oral tooth. The lingual root foramina stand out well on this one.

Occlusal View

Basal View

Lingual View

Labial View

Profile View

Profile View

This anterior has a bit of a different morphology.

Occlusal View

Basal View

Lingual View

Labial View

Profile View

A classically shaped lateral tooth. The basal root foramen shows up nicely on this one.

Occlusal View

Basal View

Lingual View

Labial View

Profile View

This is a large lateral tooth. It has a different morphology than the one above.

Occlusal View

Basal View

Lingual View

Labial View

Profile View

This lateral has a nice reddish color.

Occlusal View

Oblique View

This one is a good example of apical in vivo wear.

Occlusal View

Basal View

Lingual View

Labial View

Profile View

Profile View

This one has a strange appearance. It is possibly pathological (the crown is a bit twisted relative to the root).

Vertebrae

Rostral/Caudal Aspect

Rostral/Caudal Aspect

Side View

Oblique View

Sawfish (Ischyrhiza mira) Vertebra, Cretaceous, New Jersey

Oblique View

Sawfish vertebrae differ from shark vertebrae in that they don’t have the foramina along the edges where cartilage processes once attached. Sawfish had the processes, but they attached elsewhere.

Rostral/Caudal Aspect

Rostral/Caudal Aspect

Oblique View

A larger vertebra.

Rostral/Caudal Aspect

Rostral/Caudal Aspect

Side View

Side View

This would have been a massive vertebra if whole. I estimate that it would have been in the 2″ range.

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