Pennsylvanian Goniatite from Texas

[BobWill]

I'm having trouble getting the right name for this tiny Goniatite from Jacksboro Texas. Upper Pennsylvanian, Finis Shale Member of the Graham Formation. Small at only 7mm.

 

 

 

 

[izak_]

Can't help but awesome specimen, cute little guy! 

[caldigger]

His name is Dwayne.

[doushantuo]

Suture line is none too clear.  Finis shale goniatites tend to be more globose, anyone?

Miller & Downs (1950) Journal of Paleontology 24/2: 185-218 Ammonoids of the Pennsylvanian Finis Shale

(https://www.jstor.org/stable/1299501?seq=1#page_scan_tab_contents) is a good reference but no free access.

If all functions properly, at least you will have a species listing to go on.

[Heteromorph]

Beautiful specimen!

 

It appears to be Gonioloboceras sp. at a juvenile stage, as shown in Miller & Downs 1950. There has been all kinds of taxonomic shuffling with species in this genus since Miller & Downs 1950 which makes a species level delineation difficult. 

 

There were lots of species originally described for Gonioloboceras, many of them listed in Plummer & Scott 1937. Miller & Downs 1950 lumped most of those species into G. goniolobus. Everyone was happy with that until Elias 1962 came and blew the whole thing up again. Now G. schmidti and G. asiaticum from that paper aren’t listed anywhere I can find as being valid species in Gonioloboceras. According to Fossilworks and WMSDB, there are 5 species of Gonioloboceras (one being G. (Milleroceras) parrishi, of a monospecific subgenus), with 4 of those species occurring in the Graham Formation. They are G. (Milleroceras) parrishi, G. goniolobus, G. gracellenae, and G. welleri. 

 

I am having trouble finding much on the ontogeny of Gonioloboceras, but according to Miller & Dows 1950, Elias. 1938 shows the early ontogenetic suture development of G. goniolobus. I am trying to find that paper along with a few other later papers that could shed light on other Gonioloboceras species from the Finis Shale. In the mean time, pictures of more mature Gonioloboceras species can be seen here.

 

Here are some pages from Miller & Owens 1950. From looking at the Plate 31, your’s has a great resemblance to G. goniolobus, but because I don’t have any pictures of juvenile specimens from the other species to compare with, it is hard to say. Dwayne is difficult. 

 

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[Heteromorph]

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[Heteromorph]

Fig. 10.

 

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[BobWill]

1 hour ago, Heteromorph said:

Beautiful specimen!

 

It appears to be Gonioloboceras sp. at a juvenile stage, as shown in Miller & Downs 1950. There has been all kinds of taxonomic shuffling with species in this genus since Miller & Downs 1950 which makes a species level delineation difficult. 

have any pictures of juvenile specimens from the other species to compare with, it is hard to say. Dwayne is difficult. 

 

.

Ha! There it is on the same page you used to help me with Uddenites last week! I knew I'd seen it somewhere but never thought to check  my peripheral vision.