A 303 million year old toothache

[Petalodus12]

Hi all, 

Recently I was collecting at a locality that exposes the Duquesne Limestone and shale, which if you’ve seen any of my previous posts you’ll know that I’ve collected extensively. But for those of you that have not, the Duquesne shale is a layer of black, carbonaceous shale found in areas where the Conemaugh group is exposed. 

This layer is chalk full of disarticulated vertebrate remains, but some of the most recognizable are the teeth of Orthacanthus  and Xenacanthus. These were eel-like sharks that existed from the Devonian-Triassic and had bicuspid or tricuspid teeth. They grew to be about 10-12 feet at the largest and thrived in the swampy lakes of the late Pennsylvanian. 

 

It’s somewhat uncommon for me to find a large Orthacanthus tooth (which are tiny compared to Otodus sp. )and it is even rarer for me to find a tooth with feeding damage. It seems to me that, understandably, many collectors of Cenozoic shark teeth are disappointed when they find shark teeth with feeding damage, but for me at least when I find Paleozoic shark teeth with feeding damage it makes it even more special.
 

Last time I was collecting I did just that. Interestingly enough this Orthacanthus compressus tooth is my largest yet and has a very unusual break. The cusp that is missing is not broken cleanly at the enamel, rather, when it broke off it took a good chunk of the rooth with it. To me at least this would indicate that the shark was using quite a bit of force when it bit down, and whatever it bit in to must have been very hard and made for a painful meal for the shark. 
It’s important to note that the other cusp was damaged recently and isn’t feeding damage.
I’m not one to heavily speculate but I’d imagine that it had to have bit in to one of the heavily armored Paleoniscoids for damage of this nature to take place. Or, who knows, the tooth might have just been old. Whatever happened to break the cusp is lost to time, I guess. Regardless, I think it’s a wonderful find and reminds me that these animals were truly alive and had imperfections. 
Hopefully you all find this as interesting as I do .

[Petalodus12]

Oops, forgot to provide geologic setting.

Stratigraphy:

Duquesne Shale, Casselman Formation, Conemaugh Group

Age: Virgilian stage of the Late Pennsylvanian. ~303 MYA