Tony Eaton

Ptychodus Id Quick Guide

31 posts in this topic

The folks from the Jackson School of Geology, Vertebrate Paleontology department at the University of Texas brought a Ptychodus rugosus specimen to Fossil Fest last weekend. It was an old specimen but perfect and HUGE! maybe 2-inches (55mm) wide. Regretting not getting a picture of it.

 

Can anyone put age ranges on those listed above? Sometimes sorting them out is a lot easier when you can eliminate those too young or too old for your local.

 

PS LSCHNELLE set up a great display that included those teeth from our local strata.

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Lee, So glad you snapped some pics!

 

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The UT students said the huge single Ptychodus tooth was not a trustworthy ID as P. Rugosus - even though they can be up to 80mm wide.  My understanding from Shawn Hamm's MS paper is that P. Rugosus has a bulbous and often offset from center crown which this tooth did not have.  This tooth looks more like a huge P. Marginalis because of the concentric circles. Or, if from England, it could be P. Polygyrus. 

 

The dentition is a harder ID.  I would guess that it is a very large P. Decurrens due to its bifurcating transverse ridges extending to marginal edge and due to its numerous fine ridges on the labial and lingual margins perpendicular to the transverse ridges.  

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Erose:  Hopefully, the colored chart gives you the age and formation ranges that were looking for on Central Texas Ptychodus teeth.

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Wow, a pretty neat resource here. Cool!

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