Ptychodus mammilaris

I find the P. mammillaris vs P. anonymous sometimes a difficult diagnosis. This is one of those that looks a hair more like P. mammillaris than P. anonymous. Shawn Hamm has one tooth photo in his NMMNH Bulletin 81 that is under both species. He says that the larger Turonian P. anonymous can look a lot like P. mammillaris and visa-versa.

11 hours ago, LSCHNELLE said:

I find the P. mammillaris vs P. anonymous sometimes a difficult diagnosis. This is one of those that looks a hair more like P. mammillaris than P. anonymous. Shawn Hamm has one tooth photo in his NMMNH Bulletin 81 that is under both species. He says that the larger Turonian P. anonymous can look a lot like P. mammillaris and visa-versa.

most i'm iffy on as well - but this one probably stands out the best among the fray at the site due to the squared off crown and vertical (as opposed to slanted) drop from the top of the crown down to the sulcus, IMHO

13 hours ago, Jared C said:

most i'm iffy on as well - but this one probably stands out the best among the fray at the site due to the squared off crown and vertical (as opposed to slanted) drop from the top of the crown down to the sulcus, IMHO

Page 23 from NMMNH Bulletin 81 of associated set of Ptychodus anonymous C and D files.

....oh darn 

16 hours ago, Jared C said:

....oh darn 

Your funny!

One of the main reasons it could still be P. mammillaris is the number of ridges. - about 8 to 10 depending on how you count them in your specimen. 10 to 12 is the norm for medial P. anonymous teeth and 8 to 10 for lateral teeth. I'd say this is a medial tooth. P. mammillaris has 7 to 10 ridges in medial teeth. So, it has few enough ridges to be at the borderline. The main P. mammillaris characteristic beside a more flat crown top and fewer number of ridges is a quick and early transition from crown ridges to granular margin. Kind of like P. latissimus. This one doesn't really have that quick transition.