Let's see your Southern Midcontinent (USA) Cambrian fossils! Missouri, Oklahoma, Texas, bring it.

[pefty]

Hardly anybody ever talks about the Cambrian fossils of the southern midcontinent (USA). They're super-underappreciated. Show us what you've got!

Here's one to start us off: Thorax and pygidium of a trilobite, possibly Orygmaspis, typically referred to as "Orygmaspis cf. Orygmaspis llanoensis" but probably a different species altogether. Note the two pairs of macropleural spines marking the final thoracic segments. Davis Formation (late Cambrian: Furongian), south side of Highway 8, St. François County, Missouri.

[Diplocaulus]

I sadly do not have any Southern fossils, but I'm excited to see how this thread develops!

[pefty]

Here are some more specimens from the late Cambrian (Furongian) Davis Formation of St. François County, Missouri, USA. These were found and prepped by @California Dave.

[pefty]

One more, this one a ventral view of an Orygmaspis thoracopygon from the Davis Formation (Furongian, Missouri, USA). Note mostly buried pleural spines with tips barely emerging from sediment. 

[pefty]

Found two weeks ago by Cam: this cranidium+thorax of what appears to be Orygmaspis sp. based on the faintly visible macropleural spines. Davis Formation, Late Cambrian (Furongian), St. François County, Missouri, USA. 

[pefty]

Update on Cam’s specimen

[Ironhead42]

I have barely begun fossil hunting in Oklahoma even though I live here. I have made two trips to Texas so far to collect though. Some nice specimens you have. I am looking forward to seeing what else others post that I might find here in Oklahoma.

[pefty]

Ironhead, it's quite a state for fossils! The Ordovician (most south-central OK) is outstanding for trilobites and echinoderms, and of course the Devonian trilobites (SE OK) are world-class. The Pennsylvanian and Permian (eastern and central OK) are quite nice as well, though I haven't really spent time in them. Good Cretaceous too (southern OK)! As for the Cambrian and Mississippian, I know there are decent trilobites in both, despite the limited outcrop area. I look forward to seeing your future posts about OK finds.

[pefty]

Just saw that @Raistlin has posted a nice example of a southern midcontinent Cambrian trilobite here:

 

 

Edited June 15, 2022 by pefty

[Collector9658]

Found this interesting cambrian trilobite cranidium from the Davis Formation of Missouri. No clue on ID until it is cleaned up.

[pefty]

 

@Collector9658, if it helps, I believe this was the zone we collected in . . .

 

Edited April 4 by pefty

[Collector9658]

10 hours ago, pefty said:

 

@Collector9658, if it helps, I believe this was the zone we collected in . . .

 

Was that your group out last Saturday? I drove out to Gumbo last Saturday to look at a few different specific zones around the Davis Formation roadcuts.

[pefty]

Yes! I didn't see anyone but our group, so I assumed that collector9658 must have been one of our group members

 

Glad to share the outcrop with you. Happy to share notes anytime.

[Collector9658]

On 4/4/2024 at 9:02 PM, pefty said:

Yes! I didn't see anyone but our group, so I assumed that collector9658 must have been one of our group members

 

Glad to share the outcrop with you. Happy to share notes anytime.

Do you have a link to your all's group? Would be interested in checking it out!

 

Sure was a nice day out to collect. As they say, great minds think alike. 

[pefty]

4 hours ago, Collector9658 said:

Do you have a link to your all's group? Would be interested in checking it out!

 

For sure. Looking forward to conecting:

Eastern Missouri Society for Paleontology

https://www.facebook.com/MissouriFossilClub

http://mofossils.com

 

[Collector9658]

Here are two more nicer trilobite cranidia from the Cambrian aged Davis Formation I collected. The first looks like it is a Taenicephalus, while the second appears to be a larger Kendallina.

 

Edited 22 hours ago by Collector9658

[pefty]

Good size there! With such a long preglabellar field, I wonder if Orygmaspis might also be worth considering for that second one. I honestly have a hard time telling many of these apart.

[piranha]

The preglabellar field is a better match with what Kurtz called: Orygmaspis sp.  I will check with an upper Cambrian specialist for the current taxonomic assignment.

 

 

Kurtz, V.E. 1975
Franconian (Upper Cambrian) Trilobite Faunas from the Elvins Group of Southeast Missouri.
Journal of Paleontology, 49(6):1009-1043

[Collector9658]

25 minutes ago, pefty said:

Good size there! With such a long preglabellar field, I wonder if Orygmaspis might also be worth considering for that second one. I honestly have a hard time telling many of these apart.

I think you are probably correct. I don't have any references besides what you've shared with me, and a small sample size I took home that day. Hopefully I can get back out there sometime this year to collect a larger sample of cranidia and possible a complete specimen.

[piranha]

In the meantime, I discovered what appears to be a very good possibility: Idahoia sp.

 

 

Berg, R.R. 1953
Franconian Trilobites from Minnesota and Wisconsin.
Journal of Paleontology, 27(4):553-568

[piranha]

After some additional comparison, the best match with regard to eye position and size, appears to be a subgenus: Orygmaspis (Parabolinoides) sp.

 

I will post the relevant update if the specialists reply with any new information.