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Mackerel (Archaeolamna kopingensis aka Cretodus arcuatus aka Cretodus arcuata)

Age – Late Cretaceous; Commonality – Common; Size – average: ¾ inch, max: 9/8 inches

These teeth have a distinct look even when they are worn. They have a relatively robust triangular crown. They normally have a robust triangular cusplet on each side of the crown. The cusplets are rather massive for the size of the teeth and are thick at the base. They can sometimes have these little secondary undeveloped cusplets on them. I think these secondary cusplets are vestigial cusplets. The lingual protuberance on these teeth juts out well on anterior teeth and diminishes a little in laterals and posteriors. The nutrient groove is missing on these teeth; instead, these teeth possess a nutrient pore. Some posterior teeth have ridges on the bottom of the labial face (these may not be present in all teeth). Laterals and posteriors are more curved distally than anteriors. This shark possessed two symphyseal/parasymphyseal teeth. It also had small intermediate teeth. The anteriors and laterals are enlarged in comparison to teeth of other positions.

Symphyseal / Parasymphyseal Teeth

Symphyseal A. kopingensis teeth are scarce and have a unique shape. This shark likely had 3 symphyseal files in total.

This is another symphyseal. This one is more robust.

Here is another robust symphyseal.

Anterior Teeth

Upper anterior teeth have symmetrical root lobes and a slightly curved crown. This one is likely an upper second anterior.

This tooth is another upper anterior. It is from the same position as the one above.

This tooth has more symmetrical root lobes and is likely an upper first anterior.

Lower anterior teeth generally have a more erect crown and asymmetrical root lobes (except lower first anteriors). This one is likely a lower second anterior and has the “classical” shape of a lower anterior.

Here is another lower anterior (likely a lower second anterior). This one is probably from a sub-adult.

My largest lower anterior (likely a lower second anterior) at 1 inch.

This tooth has a large lingual protuberance and is most likely a lower first anterior. Lower first anteriors are reduced in size. They are the most symmetrical lower anteriors, but are not as symmetrical as upper A1 teeth.

This A. kopingensis is most likely another lower first anterior (there is a chance that it is actually a sub-adult upper A1); it has a much smaller lingual protuberance than the tooth above.

Intermediate Teeth

Intermediate teeth exist only in the upper jaw, in between the last anterior file and the first lateral file. They resemble lateral teeth, but are smaller, less robust, flatter, and less distally curved.

This intermediate has an interesting shortened distal root lobe. A. kopingensis likely possessed 2 intermediate files.

Lateral Teeth

Upper lateral teeth have slightly shorter root lobes than upper anterior teeth. They also have a longer mesial root lobe than distal root lobe and are very distally curved.

This upper lateral is a little more stout than the one above.

This upper lateral is likely from the same tooth file as the first lateral tooth shown.

This tooth is a sub-adult upper lateral. It is likely from the same tooth file as the first and third lateral teeth presented.

This upper lateral tooth came from a tooth file closer to the posterior of the jaw.

This sub-adult upper lateral possesses a distal secondary cusplet and a large mesial cusplet which looks like it was developing into a double cusplet.

Lower lateral teeth are less curved and less robust than the uppers. Lower lateral teeth can seem similar to lower anteriors. Lower laterals are less robust and normally have a less prominent lingual protuberance. They also have a wider and “smoother” angle between the root lobes; lower anteriors have a narrow and “sharper” angle between the root lobes.

Posterior Teeth

Posterior teeth are usually much smaller than the anteriors and laterals. Most of the posterior teeth are likely uppers. This is a relatively large tooth for a posterior and is from one of the first posterior tooth files.

Another large posterior tooth. This one has a massive mesial cusplet.

This posterior tooth is of a more usual size for posterior teeth and has labial wrinkles, a common feature in posterior teeth.

This posterior tooth is even smaller and narrower than the one above.

This posterior is similar to the one above.

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