Cretaceous Micro Teeth

[historianmichael]

I am once again looking for help identifying some micro teeth I collected from a bulk sample of a Late Cretaceous (Maastrichtian) aged outcrop on the Atlantic Coastal Plain of the US. My apologies for the lack of scale. I have put the measurement of each fossil next to the description as well as a guess on what they might be. Any help would be greatly appreciated. Thank you!

 

#1 - 2.5mm - ???

  

 

 

#2 - 1.5mm - Rhinobatus sp.?

  

 

#3 - 1.25mm - Protoplatyrhina renae?

 

 

 

#4 - 2mm - Pseudohypolophus mcnultyi?

  

 

#5 - 2mm - Albulidae indet.?

  

 

Edited August 1 by historianmichael

[Mikrogeophagus]

1) Resembles a worn Rhombodus. There are some tooth positions here in TX that are ascribed to R. binkhorsti that have the same shape.

 

2) I think you are right. Not familiar with what Rhinobatos species are present on East coast, but here in TX Kemp Clay, Cappetta and Case report R. craddocki and R. uvulatus

 

3+4) No solid answer for me between "Pseudohypolophus mcnultyi" and Protoplatyrhina renae. I suspect they are both "P. mcnultyi", but I have a hard time differentiating this taxon from Protoplatyrhina. I think P. mcnultyi is supposed to be strongly rhomboidal or hexagonal in outline while P. renae is rounder and generally smaller, but not 100%. Note P. mcnultyi is also a bucket taxon that is reported to be present from the Albian to Maastrichtian and likely represents multiple species.

 

5) I think you're right

[Al Dente]

1) This looks like a tooth we commonly find in NC that I don't think has been described. They look like an off center Rhombodus.

2) Looks like Rhinobatos

3) Pseudohypolophus

4) Pseudohypolophus

5) Some call these Fisherichthys. This is normally a Paleogene genus, but identical looking teeth are found in the late Cretaceous.

[historianmichael]

@Mikrogeophagus and @Al Dente, thank you so much for your feedback.

 

The reason that I ascribed Protoplatyrhina renae to this tooth and several others is the appearance of a weak lingual protuberance, which I have noted with an arrow. I read in Welton and Farish's The Collector's Guide to Fossil Sharks and Rays From the Cretaceous of Texas that a lingual protuberance is a distinguishing characteristic of P. renae. What do you think?

 

[Mikrogeophagus]

Ah that's something I was not aware of. I guess similar to Rhinobatos, they possess a "uvula". I'm not sure if that "lingual protuberance" would qualify as a uvula. The ones on Elasmo.com seem to have uvulae that more strongly taper off of the crown when seen from a lateral view. Again, not an expert on this by any means. Hopefully @Al Dente has a more definitive insight.

 

I'll have to go back through some of my specimens and look for uvulae now

[Al Dente]

11 hours ago, historianmichael said:

The reason that I ascribed Protoplatyrhina renae to this tooth and several others is the appearance of a weak lingual protuberance, which I have noted with an arrow. I read in Welton and Farish's The Collector's Guide to Fossil Sharks and Rays From the Cretaceous of Texas that a lingual protuberance is a distinguishing characteristic of P. renae. What do you think?

 

9 hours ago, Mikrogeophagus said:

Hopefully @Al Dente has a more definitive insight.

 

The original description of Protoplatyrhina says it has a heart-shaped root. Unfortunately, almost all of the papers I have that identified Protoplatyrhina in their fauna show a root that looks identical to Pseudohypolophus. Not sure why they chose Protoplatyrhina over Pseudohypolophus as their genus. The problem is, once one person identifies it that way, everyone else follows. 

[historianmichael]

@Al Dente I completely agree with your point about once one person identifies it one way, everyone else follows. For what it is worth, I have come across at least four teeth that have this lingual protuberance, which seems different from the typical Pseudohypolophus crown.