Some Texas Cretaceous ID Questions

[JamieLynn]

Hello all! Have found a few things lately that I am having a hard time ID'ing.. Any help would be appreciated! 

 

Found in Blanco County -I had hoped this was a heteromoph, but I don't think there are heteromorphs in the Glen Rose (are there?) and I saw on another forum that heteromorphs spiral clockwise and gastropods spiral counterclockwise. Is that correct also?  So if it's a gastropod, thinking it could be either a Belliscala or an Epitonium but neither of those are found in the Glen Rose. 

 

 

 

Second Item - Found in Shoal Creek in Austin. The pattern is not quite regular enough to be ammonite, so perhpas a bivalve? 

 

 

 

 

Third is an Oyster/Bivalve. It looks most like a Texigraphea roumeri, but not quite.... I thought it was Ostrea crenulimargo, but it doesn't have as many lobes.

 

 

Lastly, an echinoid from Coryell County. Not sure of the formation, probably Walnut. It's a Coenholectypus, but it has a notch instead of an oval periproct...is it a nanus, perhaps? 

 

 

Thanks for any help!! 

 

 

 

 

 

[JamieLynn]

Hoping maybe someone might have some ideas?

[erose]

OK, here we go....

 

I don't have my HGMS gastropod book in front of me so I can't even begin to suggest what that is. The vast majority of our Cretaceous Texas gastropods are only known from steinkerns with almost no clue to what the original shell ornament looked like. You might have to look at references for the same time period from other locals for these.

 

The second item appears to be a worn internal cast of a large "Lopha" type of bivalve. That's probably as good as you will get on that one.

 

Three is Texigryphaea. What species I can't say without knowing the formation. Certainly several suspects.

 

Fourth you have correct as a species of Coenholectypus. It is probably just a small C. planatus.  There were several other species originally listed for the lower Fredericksburg Group, but several paleontologists have reviewed them and now consider them just the normal variation within C. planatus.  Labeling it Coenholectypus sp. would still be a solid ID. Years ago this had me all flumoxed as I was trying to identify a fairly large assemblage of Coenholectypus from the lower Walnut Formation in Travis County. Several collectors had assured me that there were at least two species present and I just needed to sort them out.  I placed them all on my desk and tried to sort them by height, round vs pentagonal, position of peristome, etc. They just formed one smooth scale with no distinct break from one set of features to the next. They are all now labeled as Coenholectypus planatus.

 

 

[JamieLynn]

Thanks Erich! I appreciate you taking the time to answer!\.   Yes, I am noticing that there is a pretty wide variety when it comes to the Coenholectypus.  Was just hoping I had found something new to me! hahhahah!