Pennsylvanian scaphopod ?

[BobWill]

I am finding these cone-shaped fossils in the Finis Shale member of the Graham Formation, Virgilian Series of the Pennsylvanian sub-period near Jacksboro Texas. They seem too recent for tentaculites, hollow and too tapered for crinoid stems, unsegmented and without visible septa ruling out cephalopods. The slight curve and open ends suggest scaphopod  but is there one with concentric ribs like this? Scale is millimeters.

 

[doushantuo]

cornulitids?

I'll let that one stand, they're probably indeed Scaphopods, even those with transverse ornament

Edited November 2 by doushantuo

[TqB]

Unusual and very neat. This is the closest I've seen, in Godefroid et all, 2006, "Restudy of the Lower Carboniferous Scaphopoda described by DE KONINCK 􏰁1843, 1883)".
 

 

[BobWill]

41 minutes ago, TqB said:

Unusual and very neat. This is the closest I've seen, in Godefroid et all, 2006, "Restudy of the Lower Carboniferous Scaphopoda described by DE KONINCK 􏰁1843, 1883)".
 

 

@ClearLake is it possible these could come out of the recently sampled site? The title says "lower" Carboniferous so maybe not. The ornamentation seems different from either the Prodentalium or the Plagioglypta  examples from the area you helped the study group with.

[ClearLake]

Bob, @BobWill  I have indeed found a half dozen identical fragments from that site (see picture below, yellow bar is one cm) from the matrix you collected for me.  They are certainly more coarsely ringed than any scaphopods I have seen in the literature or collected from the Paleozoic, but are undoubtedly some species of Plagioglypta.  In the Pennsylvanian, if they have longitudinal ribbing, they are Prodentalium, if they have transverse ribbing (as these do), they are Plagioglypta.  The page snippet below is from Girty (1915) from the Wewoka Fm. of Oklahoma and I think is one of the better diagrams (figures 15 and 16) that illustrate something similar to what you show .  Below that is a slide I put together for the DPS group which summarizes the Pennsylvanian Scaphopoda (there is not a great deal to summarize).  As the slide mentions, there are other Pennsylvanian Plagioglypta species from US areas outside the mid-continent.  I'll have to see if I can dig up pictures of those to see if any are a closer match for these.  Dr. Yancy has written several of the papers on scaphopods, so might be a good person we can check with.  I should mention that the nomenclature I am using is that suggested by Young (1942) and supported by Emerson (1962) and Yancy (1978).  The paper referenced by @TqB is very interesting and brings up lots of good inaccuracies in Paleozoic scaphopod systematics, but I will leave resolution of that for more academic workers. 

 

Suffice it to say, the specimens that Bob has shown in his post bear many of the trademarks of scaphopods (tubular, gently curved, expanding, etc), but there may be other more obscure molluscan fauna that are also candidates (I don't know what those are).

 

[Missourian]

On 11/2/2024 at 9:11 AM, BobWill said:

 

Nice foram Ammovertella sp. attached to the shell in the upper left