Ptychodus and a Lamniformes from the Lake Waco Formation

[fossilsonwheels]

I could use a little help identifying a few teeth from the Lake Waco Formation. That’s the geological  info I was given at least. I’m not familiar with the formation so I’m not sure of the age. 

 

First up, 2 small Ptychodus teeth. Both around 7mm. Very low crown. I’m not great with Ptychodus ID’s so I could be way off but I think these could be P. rhombodus based on some pictures I’ve seen. I don’t have any other Ptychodus teeth that look quite like this. 

[fossilsonwheels]

I thought this was a Cretodus semiplicatus tooth at first but I’m questioning that. Could it be a good sized Protolamna tooth instead ? 

 It’s 2.1cm in size. 

 

[ThePhysicist]

Sorry can't help with Ptychodus. @LSCHNELLE

 

As for the lamniform, looks like Protolamna with that really narrow crown. 

^http://northtexasfossils.com/sharks.htm

[Planko]

@will stevenson 

[fossilsonwheels]

25 minutes ago, ThePhysicist said:

Sorry can't help with Ptychodus. @LSCHNELLE

 

As for the lamniform, looks like Protolamna with that really narrow crown. 

^http://northtexasfossils.com/sharks.htm

Yup. Pretty much spot on. Protolamna it is. 

[Notidanodon]

i agree with protolamna, for the ptychodus, i would go with decurrens, but i need better images of the ridges to be really sure  

[siteseer]

When I started collecting, teeth from the Waco area were said to come from the Del Rio Clay.  As I recall, some thought it was late Albian age while others sided with early Cenomanian and I think most people say now that the age is early Cenomanian.  There were two sites collectors talked about: the "pit" and the "lake" both of which yielded teeth of about the same age if not the same age.

 

I agree that the first tooth is P. decurrens, which is what you tend to get in Ptychodus of that age (also rather flat with several ridges in a more chaotic-looking pattern than later Ptychodus), and the second is Protolamna which tends to be smaller, have more distinct folds on both the labial and lingual faces, have more broadly-united cusplets with the main cusp and the cusplets tend to curve more toward the cusp.  In Cretodus the folds can be hard to see or clearly present but not as raised as in Protolamna.  The cusplets in Cretodus can seem small and tend to point away from the cusp.

[fossilsonwheels]

Hi Jess

 

Thanks for the information as always. Seems like to consensus is Protolamna and Ptychodus decurrens, which is great because I had no other decurrens in the collection. I have teeth from both the pit and the lake I think. 

 

Thank you my friend 

[fossilsonwheels]

7 hours ago, will stevenson said:

i agree with protolamna, for the ptychodus, i would go with decurrens, but i need better images of the ridges to be really sure  

Thanks for the help Will. I’m happy to go with decurrens. That’s not a bad species to have at all. 

[Notidanodon]

5 hours ago, fossilsonwheels said:

Thanks for the help Will. I’m happy to go with decurrens. That’s not a bad species to have at all. 

No problem at all, happy to help  

[LSCHNELLE]

On 2/13/2022 at 10:35 PM, siteseer said:

When I started collecting, teeth from the Waco area were said to come from the Del Rio Clay.  As I recall, some thought it was late Albian age while others sided with early Cenomanian and I think most people say now that the age is early Cenomanian.  There were two sites collectors talked about: the "pit" and the "lake" both of which yielded teeth of about the same age if not the same age.

 

I agree that the first tooth is P. decurrens, which is what you tend to get in Ptychodus of that age (also rather flat with several ridges in a more chaotic-looking pattern than later Ptychodus), and the second is Protolamna which tends to be smaller, have more distinct folds on both the labial and lingual faces, have more broadly-united cusplets with the main cusp and the cusplets tend to curve more toward the cusp.  In Cretodus the folds can be hard to see or clearly present but not as raised as in Protolamna.  The cusplets in Cretodus can seem small and tend to point away from the cusp.

Nice finds @FossilsonWheels

 

I have no experience with finding Ptychodus in the Lake Waco Member, but I hunted there once without success.  I have hunted the Belton area with some success finding either P. occidentalis (or P. decurrens) in the Lower Cenomanian Pepper Shale. But, I found nothing above it in the Lake Flow member of the Eagle Ford (U.T. Bureau of Economic Geology).

 

My understanding from recent professional studies, is that the lower part of the Lake Waco Member is Middle Cenomanian and the other part is Upper Cenomanian. Just a year or two ago I would have thought this was also Ptychodus decurrens.  And, it may very well be. But, Shawn Hamm thinks that doesn't occur in the United States until the Turonian. So, you wouldn't be finding it in this ancient strata.  Instead there or only two or three species of Ptychodus that you might find in Cenomanian strata.  P. anonymous and P. occidentalis.  The P. rhombodus is a possibility, but Shawn's Bulletin 81 records his opinion that the P. rhombodus finds in Canada that were professionally evaluated may be instead a juvenile P. occidentalis.

 

So per Shawn Hamm's recent opinions, since your teeth are low crown (not higher like P. anonymous), they are most likely P. occidentalis juvenile teeth or adult anterolaterals or posteriors. I personally have found P. decurrens in Travis County in the Upper Cenomanian Bouldin Flags member of the Eagle Ford Shale.  So, I'm not convinced that P. decurrens may not also be present in the Middle Cenomanian. 

Edited February 15, 2022 by LSCHNELLE
Typo

[fossilsonwheels]

8 hours ago, LSCHNELLE said:

Nice finds @FossilsonWheels

 

I have no experience with finding Ptychodus in the Lake Waco Member, but I hunted there once without success.  I have hunted the Belton area with some success finding either P. occidentalis (or P. decurrens) in the Lower Cenomanian Pepper Shale. But, I found nothing above it in the Lake Flow member of the Eagle Ford (U.T. Bureau of Economic Geology).

 

My understanding from recent professional studies, is that the lower part of the Lake Waco Member is Middle Cenomanian and the other part is Upper Cenomanian. Just a year or two ago I would have thought this was also Ptychodus decurrens.  And, it may very well be. But, Shawn Hamm thinks that doesn't occur in the United States until the Turonian. So, you wouldn't be finding it in this ancient strata.  Instead there or only two or three species of Ptychodus that you might find in Cenomanian strata.  P. anonymous and P. occidentalis.  The P. rhombodus is a possibility, but Shawn's Bulletin 81 records his opinion that the P. rhombodus finds in Canada that were professionally evaluated may be instead a juvenile P. occidentalis.

 

So per Shawn Hamm's recent opinions, since your teeth are low crown (not higher like P. anonymous), they are most likely P. occidentalis juvenile teeth or adult anterolaterals or posteriors. I personally have found P. decurrens in Travis County in the Upper Cenomanian Bouldin Flags member of the Eagle Ford Shale.  So, I'm not convinced that P. decurrens may not also be present in the Middle Cenomanian. 

I didn’t personally find these so I’m relying on the source for the geological information. I will double check that information. 

Very interesting information. I had not even considered P. occidentalis but my knowledge of Ptychodus species is pretty limited. I appreciate the assistance. 

[siteseer]

15 hours ago, LSCHNELLE said:

Nice finds @FossilsonWheels

 

I have no experience with finding Ptychodus in the Lake Waco Member, but I hunted there once without success.  I have hunted the Belton area with some success finding either P. occidentalis (or P. decurrens) in the Lower Cenomanian Pepper Shale. But, I found nothing above it in the Lake Flow member of the Eagle Ford (U.T. Bureau of Economic Geology).

 

My understanding from recent professional studies, is that the lower part of the Lake Waco Member is Middle Cenomanian and the other part is Upper Cenomanian. Just a year or two ago I would have thought this was also Ptychodus decurrens.  And, it may very well be. But, Shawn Hamm thinks that doesn't occur in the United States until the Turonian. So, you wouldn't be finding it in this ancient strata.  Instead there or only two or three species of Ptychodus that you might find in Cenomanian strata.  P. anonymous and P. occidentalis.  The P. rhombodus is a possibility, but Shawn's Bulletin 81 records his opinion that the P. rhombodus finds in Canada that were professionally evaluated may be instead a juvenile P. occidentalis.

 

So per Shawn Hamm's recent opinions, since your teeth are low crown (not higher like P. anonymous), they are most likely P. occidentalis juvenile teeth or adult anterolaterals or posteriors. I personally have found P. decurrens in Travis County in the Upper Cenomanian Bouldin Flags member of the Eagle Ford Shale.  So, I'm not convinced that P. decurrens may not also be present in the Middle Cenomanian. 

 

That would be very interesting if those teeth are being considered juvenile P. occidentalis.  It might explain what I have from other sites but P. occidentalis adult teeth bear high, bulbous crowns.  I've never seen adult occidentalis teeth from Waco.  I've never collected there, though - just have seen some teeth.  I used to see a lot more teeth from there but I heard collecting is more restricted now.  As I recall, Ptychodus is rare.

 

[Jared C]

22 hours ago, LSCHNELLE said:

So per Shawn Hamm's recent opinions, since your teeth are low crown (not higher like P. anonymous), they are most likely P. occidentalis juvenile teeth or adult anterolaterals or posteriors. I personally have found P. decurrens in Travis County in the Upper Cenomanian Bouldin Flags member of the Eagle Ford Shale.  So, I'm not convinced that P. decurrens may not also be present in the Middle Cenomanian. 

I have nothing to add, I'd just like to say thank you for the incredibly informative posts, as usual 

[LSCHNELLE]

See below response to Jared C. 

Edited February 17, 2022 by LSCHNELLE
Changed to redirect reply to Jared C from fossilsonwheels

[LSCHNELLE]

On 2/16/2022 at 10:11 AM, Jared C said:

I have nothing to add, I'd just like to say thank you for the incredibly informative posts, as usual 

I have enjoyed sharing any knowledge I may have learned (from Shawn or from my own wanderings) with the TFF community.  Certainly, knowledge is always a moving target like the geology in the local streams after a flooding event.  What we learn today may not be useful tomorrow. Maybe we can take a fossil hunt together someday - after this pandemic subsides a little more.  Regardless, I'm looking forward to finding out more about your basal mosasaur find from Dr. Polcyn @Jared C. 

Edited February 17, 2022 by LSCHNELLE

[Jared C]

20 minutes ago, LSCHNELLE said:

I have enjoyed sharing any knowledge I may have learned (from Shawn or from my own wanderings) with the TFF community.  Certainly, knowledge is always a moving target like the geology in the local streams after a flooding event.  What we learn today may not be useful tomorrow. Maybe we can take a fossil hunt together someday - after this pandemic subsides a little more.  Regardless, I'm looking forward to finding out more about your basal mosasaur find from Dr. Polcyn @Jared C. 

I'd be glad to! Prep is slow, but oddly enough Hamm also has a small role in our endeavor with this specimen. To avoid spoiling research publicly, I'll PM you a few of the updates as they come - only fair since you helped so much early on with the geology of the find 

[LSCHNELLE]

On 2/15/2022 at 11:53 AM, LSCHNELLE said:

Nice finds @FossilsonWheels

 

I have no experience with finding Ptychodus in the Lake Waco Member, but I hunted there once without success.  I have hunted the Belton area with some success finding either P. occidentalis (or P. decurrens) in the Lower Cenomanian Pepper Shale. But, I found nothing above it in the Lake Flow member of the Eagle Ford (U.T. Bureau of Economic Geology).

 

My understanding from recent professional studies, is that the lower part of the Lake Waco Member is Middle Cenomanian and the other part is Upper Cenomanian. Just a year or two ago I would have thought this was also Ptychodus decurrens.  And, it may very well be. But, Shawn Hamm thinks that doesn't occur in the United States until the Turonian. So, you wouldn't be finding it in this ancient strata.  Instead there or only two or three species of Ptychodus that you might find in Cenomanian strata.  P. anonymous and P. occidentalis.  The P. rhombodus is a possibility, but Shawn's Bulletin 81 records his opinion that the P. rhombodus finds in Canada that were professionally evaluated may be instead a juvenile P. occidentalis.

 

So per Shawn Hamm's recent opinions, since your teeth are low crown (not higher like P. anonymous), they are most likely P. occidentalis juvenile teeth or adult anterolaterals or posteriors. I personally have found P. decurrens in Travis County in the Upper Cenomanian Bouldin Flags member of the Eagle Ford Shale.  So, I'm not convinced that P. decurrens may not also be present in the Middle Cenomanian. 

A slight update to my previous post. I was reading NMMNH Bulletin 81 this AM with a focus on Ptychodus decurrens.  The type specimen was an associated tooth set from Late Cenomanian of the English Chalk. Multiple experts think that P. decurrens was more of a deep water dweller and that it migrated from Europe to the southern end of the Western interior Seaway (WIS) in North America.  Therefore, it is present in the southern WIS in higher concentrations beginning in the Late Cenomanian Greenhorn Cyclothem.  It has been reported in the Dakota Formation from the Middle Cenomanian, but I wonder whether Shawn would say that was potentially a stratigraphic error.  While it is true that P. occidentalis generally has high crowned symphosials, the same cannot be said for the laterals, posteriors, or for juvenile teeth.  So, this is where it's difficult to tell P. rhombodus from P. decurrens from P. occidentalis.  Therefore, based on a middle Cenomanian age @fossilsonwheels it is more likely to be a P. occidentalis.   If it were from the Late Cenomanian part of the WIS, then odds are greater that it could be a P. decurrens vs P. occidentalis which has a declining presence in the Early and Middle Turonian.  I haven't found P. occidentalis in Central Texas later than the Cenomanian. It's most abundant in the Cenomanian.