Ptychodus Perfection

[sharko69]

Found this beauty a couple of weeks ago. I have identified it as P. atcoencis because of the chevron pattern but the crown is very low and it has more ridges then teeth I have previously found. Thoughts?

[Brittle Star]

It is wonderful whatever it is.

[Tidgy's Dad]

Mmm. Ptychodus marginalis, maybe?

[JarrodB]

Perfect!

[Ludwigia]

I don't know much about teeth, but I know what I like

[Miocene_Mason]

Awesome find! All the ones in my collection are dinged up and sun bleached, the complete beautiful ones must be super rare!

[sharko69]

14 hours ago, WhodamanHD said:

Awesome find! All the ones in my collection are dinged up and sun bleached, the complete beautiful ones must be super rare!

Thank you. I have around 400 Ptychodus and have only a handful in this condition. It is always fun to find teeth in great condition. I do however really like when you can see the wear caused by the animal eating. I think they tell a special story as well.

[LSCHNELLE]

Do you know which geologic formation and/or member it came from?  Was it Atco, or Eagle Ford:  Kamp Ranch (S. Bosque), or Arcadia Park (flaggy member)? Or, was it loosened from the rock matrix?

[abyssunder]

There is a precious document  in the pinned "Ptychodus Id Quick Guide" topic, which might help.

[LSCHNELLE]

Without further information on the strata, I would lean toward Ptychodus  mammillaris due to flattened crown. Not P. marginalis, since no concentric ridges pattern. P. atcoensis (only from Atco Formation) and others with moderate crown height typically have a more rounded or conical crown. Usually, P. atcoensis chevron pattern crosses most or all ridges. Yet, it might still be a variation of P. atcoensis if from Atco Formation. 

[sharko69]

19 hours ago, LSCHNELLE said:

Do you know which geologic formation and/or member it came from?  Was it Atco, or Eagle Ford:  Kamp Ranch (S. Bosque), or Arcadia Park (flaggy member)? Or, was it loosened from the rock matrix?

Sorry. Forgot to add. Eagle Ford, Sherman. Was found loose.

18 hours ago, abyssunder said:

There is a precious document  in the pinned "Ptychodus Id Quick Guide" topic, which might help.

Thank you. Yes, that is a great reference that I use with regularity. Still left me with a few questions on this identification.

[sharko69]

Attached is a P. atcoensis from the same area in the Eagle Ford/ Atco contact.

[LSCHNELLE]

22 minutes ago, sharko69 said:

Sorry. Forgot to add. Eagle Ford.

Thank you. Yes, that is a great reference that I use with regularity. Still left me with a few questions on this identification.

This is not P. atcoensis if from Eagle Ford.  P. mammilaris has a flattened crown and from 7 to 10 ridges. This tooth fits that description. The chevron folds on the two ends can occur as an irregularity on P. mammilaris, but usually the ridges are straight across. On other Eagle Ford Ptychodus, the ridges often  extend to the edges of the margins. These stop near the center of the margin. 

[doushantuo]

 

 

 

 

FROM:

bricenoptycompletsatcoens13358-013-0053-3.pdf

[LSCHNELLE]

31 minutes ago, doushantuo said:

 

 

 

 

FROM:

bricenoptycompletsatcoens13358-013-0053-3.pdf

doushantuo: Thanks for sharing that PDF article. I have not been able to obtain a copy of it yet.  The tooth you took a snapshot of appears to be close to sharko69 images. So, if it is from the Atco contact and not the Kamp Ranch/South Bosque, then definitely P. atcoensis.  If not, then P. mammilaris. 

[doushantuo]

From a classic and classy study of P. mediterranensis:

 

line drawing of specimen,1/4 nat.size

 

 

 

 

 

 

 

[siteseer]

On 12/14/2017 at 7:48 AM, LSCHNELLE said:

doushantuo: Thanks for sharing that PDF article. I have not been able to obtain a copy of it yet.  The tooth you took a snapshot of appears to be close to sharko69 images. So, if it is from the Atco contact and not the Kamp Ranch/South Bosque, then definitely P. atcoensis.  If not, then P. mammilaris. 

 

I remember when I met Bruce Welton back in 1994 (he and Roger Farish) was doing signings at shows, promoting the book), I was talking to him about his years collecting in southern California.  A collector was behind me and he wanted an ID on an oddball Ptychodus (something like this one showing features of two different species).  Bruce kind of sighed and muttered something about Ptychodus not always being easy to Identify to species.

 

With this tooth if pressed for one ID, I would say P. mammilaris because P. atcoensis has such a distnct cusp, appearing to have grown vertically out of the marginal area like a bulb.  The tooth in question has a cusp that has a more gradual slope to it from one angle.  I would expect the cusp to be a little higher in a P. atcoensis tooth of that overall size.

 

Jess

 

[LSCHNELLE]

On 12/15/2017 at 8:34 PM, siteseer said:

 

I remember when I met Bruce Welton back in 1994 (he and Roger Farish) was doing signings at shows, promoting the book), I was talking to him about his years collecting in southern California.  A collector was behind me and he wanted an ID on an oddball Ptychodus (something like this one showing features of two different species).  Bruce kind of sighed and muttered something about Ptychodus not always being easy to Identify to species.

 

With this tooth if pressed for one ID, I would say P. mammilaris because P. atcoensis has such a distnct cusp, appearing to have grown vertically out of the marginal area like a bulb.  The tooth in question has a cusp that has a more gradual slope to it from one angle.  I would expect the cusp to be a little higher in a P. atcoensis tooth of that overall size.

 

Jess

 

Jess - good observation. I would agree. If truly from Eagle Ford, then P. mammilaris is the best guess. 

[abyssunder]

As I'm not well versed in this (but curious), it's better to ask, because that's the way how we learn from the more knowledgeable people. Is the tooth in question a lateral file tooth or not?

[LSCHNELLE]

I am not an expert either - just learning some from Shawn Hamm.  That said, my guess is that it is a medial or para-medial file. I think lateral files are not as rectangular, lack symmetry, and the crown is offset from the root. They also can be much harder to identify. 

[JarrodB]

Roger Farish is the resident tooth expert in our area and a really nice guy. He normally helps me with ID's. 

[sharko69]

On 12/19/2017 at 4:34 PM, LSCHNELLE said:

Jess - good observation. I would agree. If truly from Eagle Ford, then P. mammilaris is the best guess. 

Received confirmation this evening that the tooth in question is indeed P. atcoensis. Confirmed by Shawn Hamm.

[LSCHNELLE]

sharko69:  If Shawn is right then, as I said before, you had to be in the Atco Formation of the Austin Group or in the transition. Or, the fossil in question dropped down from the Atco into the Eagle Ford as drift material. 

[sharko69]

20 hours ago, LSCHNELLE said:

sharko69:  If Shawn is right then, as I said before, you had to be in the Atco Formation of the Austin Group or in the transition. Or, the fossil in question dropped down from the Atco into the Eagle Ford as drift material. 

It was found at Post Oak Creek in Sherman. Couldn’t have drifted far to stay in that condition but was float material so that is of coarse possible.