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Fossils from Monmouth County, New Jersey

Crow (Squalicorax kaupi“)

Age – Late Cretaceous; Commonality – S. pristodontus- common, S. kaupi- very common Size- Pristodontus- average- ¾ inches, max- up to a little over an inch (in our area) Kaupi- average- ½ inch max-3/4

The teeth of the crow sharks vary in shape more than any other species present here. Their teeth are flattened and normally have a greater width than length (in laterals). Crow shark teeth are also the only serrated type of shark tooth found here. The ratio between tooth length and width gets smaller as you go further back into their mouth. They sort of don’t have an “anterior tooth” or “lateral position” or “posterior position”, such as in Scapanorhynchus teeth. It is just the tooth angle that changes. Anterior teeth have more of a straight shape, and posteriors are more curved distally. Their anteriormost teeth resemble symphysial teeth. The symphysial teeth are rather strange in appearance. They have a much narrower root than the normal crow teeth. The two types of Squalicorax teeth present are S. pristodontus and S.kaupi“. S. pristodontus teeth are larger on average and have a wider angle in the notch on the distal part of the tooth. Quotations are placed around “kaupi” because it is a paleobucket term which includes more than one species. It will likely be very difficult to determine what how many “kaupi” species there really are.

Symphyseal Tooth

Lingual View

Labial View

Crow Shark Cretaceous (Squalicorax kaupi) Symphyseal tooth, New Jersey

This tooth is most likely a symphyseal. There is a small chance it could be an extreme anterior tooth, but its morphology matches better with a symphyseal tooth. Symphyseal Squalicorax teeth usually look different than this – they have one root lobe, are hook-like, and have serrations only on one side of the crown. Note the absence of a distal notch on this symphyseal.

Anterior Teeth

Lingual View

Labial View

This tooth is likely a first anterior. The anteriors possess a roughly obtuse distal notch angle and have an elongated appearance.

Lingual View

Labial View

Crow Shark Cretaceous (Squalicorax kaupi) Anterior tooth, New Jersey

This anterior has a small root and a large crown.

Lingual View

Labial View

This tooth looks like a classical anterior tooth.

Lingual View

Labial View

This anterior likely came from slightly further back in the jaw in comparison to the tooth above.

Lingual View

Labial View

This tooth has some strange serrations near the tip. I thought the serrations were sheared off at the tip at first, but upon further examination it appears that they simply dwindle in size towards the tip. It would be unlikely that they were sheared off because the serrations get smaller on both the mesial and distal carinae, the enamel is present on the carinae, and the serrations due not come to an abrupt end.

Anterolateral Teeth

Lingual View

Labial View

Crow Shark Cretaceous (Squalicorax kaupi) Anterolateral tooth, New Jersey

I classified these teeth as anterolateral teeth because I feel that they are an intermediate form between the anterior teeth and the lateral teeth. They are slightly less elongated and have a smaller distal notch angle.

Lingual View

Labial View

This tooth has a different morphology than the one above. It may be due to many different factors such as whether it came from the upper or lower jaw (this is not possible as paleontologists haven’t found a way to differentiate uppers and lowers) and the sex of the shark. It is likely due to just tooth variation.

Lingual View

Labial View

This tooth is a great example of how the root lobes in this species differ from the roots of the other sharks. In most sharks (Scapanorhynchus is a good example) the mesial root lobe is larger (usually longer) than the distal one. In many anterior and anterolateral teeth of S. kaupi the distal root lobe is larger than the mesial root lobe.

Lingual View

Labial View

This tooth has a markedly different morphology than the other anterolaterals. It has a relatively deeper distal notch and a small mesial notch. It also has a different root shape.

Lateral Teeth

Lingual View

Labial View

Lateral teeth are broader and more distally angled. The root lobes are shorter than on the more anterior teeth.

Lingual View

Labial View

This lateral has even shorter root lobes than the tooth above.

Lingual View

Labial View

Crow Shark Cretaceous (Squalicorax kaupi) Lateral tooth, New Jersey

This tooth is from a juvenile. It is significantly smaller and less robust than the adult ones shown above. Juvenile teeth are less common than adult teeth.

Lingual View

Labial View

This is another juvenile tooth. It is very similar to the one shown above.

Lingual View

Labial View

This juvenile tooth is from further back in the mouth, but I still consider it a lateral. It has longer root lobes and a more distally angled crown compared to the other two juvenile lateral teeth.

Lingual View

Labial View

This juvenile tooth has a very interesting root shape. It is very bilobate, unlike most Squalicorax teeth which have a main root with two very small root lobes.

Posterior Teeth

Lingual View

Labial View

Crow Shark Cretaceous (Squalicorax kaupi) Posterior tooth, New Jersey

Posterior teeth look distinctly different. They are very curved backward toward the distal side. The distal notch usually has an acute angle.

Lingual View

Labial View

This posterior tooth is different from the norm. It does not really curve like the “usual” posterior teeth. This tooth is a posterior because of the relatively low crown. It also has a couple interesting features. The distal notch is almost nonexistent – it looks like a little bud next to the crown. The mesial serrations on the upper part of the crown are significantly smaller than the serrations on the lower part of the crown.

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