Carcharocles Confusion

[Rocks Anne]

Found on N Topsail Beach, NC, in October of 2015 (not long after a dredging and sand replacement project). Longest edge is 6 cm.

 

Various "authorities" have offered conflicting id's. I don't have many fossils worth showing anybody and I'd like to be able to tell visitors definitively what it is.

 

I did read the various threads on this topic in the forum and looked it up in other sources, as well. However, I found researching Carcharocles auriculatus vs Carcharocles angustidens much like watching a pack of hound dogs turned loose on a truckload of rabbits released in the forest.

Would appreciate opinions from those knowledgeable on the current theories regarding this (apparent) debate. Or is it just evolution of opinion?

 

[Plax]

These are the same shark viewed as different species as they evolve over time. The River Bend and Belgrade, two possibilities for the Topsail Dredgings are both Oligocene. Auriculaltis is an Eocene chronospecies that evolves into angustidens in the Oligocene. If you want to go by the stratigraphy you can call it angustidens but I doubt anyone will definitely tell you one or the other if it is transitional in taxonomic characteristics. The North Carolina Fossil Club fish volume may give diagnostic features to separate the two as elasmo.com may.

[sixgill pete]

Just due to the fact that it came from Topsail during the beach re-nourishment project, I would call it angustidens, although I have seen early River Bend teeth that look more like auriculatus. Also the Genus is now Otodus, not Carcharocles.