Odd Trilobite Pygidium, Ordo. Age Galena Formation

[Caleb]

Here is a mystery for the trilobite people(me being one of them). This is a pygidium found in the Galena Formation of Southeast Minnesota. We think we've got it narrowed down to the Family Cheiruridae, but that's about it.

Enjoy and ponder

[piranha]

Two middle Ordovician cheirurids immediately pop off the screen. I've attached a few photo plates for comparison. The Pseudosphaerexochus that is figured in the Treatise and elsewhere can be quite different depending on species. The example posted is a Baltic-Scandinavian variant, P. inflatus, so difficult to interpret in this context. My inclination is leaning toward Heliomeroides spp. recorded across North America in California, Newfoundland, New York, Virginia and Vermont (Whiterockian-Blackriveran). Not too far a stretch to imagine a pit-stop in Minnesota as well? There are another 100+ papers that I'd like to go through but wanted to get the ball rolling with these... Perhaps another undescribed trilobite to accompany the new Thaleops?

RE: An Early Ordovician Trilobite Fauna from Bornholm

Geological Institute of the University of Copenhagen: 1965

Valdemar Poulsen

RE: Some Middle Ordovician Trilobites of the Families Cheiruridae, Harpidae

and Lichidae Journal of Paleontology, Vol. 25, No. 5 (Sep., 1951), pp. 587-616

William R. Evitt

Heliomeroides

Pseudosphaerexochus

[Caleb]

I think this very well may be a new one to go with the Thaleops(along with a few others). One of my fathers ideas might be a Pandaspinapyga. Galena in this area is very similar in age with the Kimswick of Missouri. While I have no idea what this trilobite looks like, it may be a lead? This pygidium is certainly like nothing we have come across in the 16 years I've been collecting and the 35+ years my father has.

Pandaspinapyga, a New Trilobite Genus from the Kimmswick Limestone (Ordovician) of Missouri (Esker, G. C. & Levin, H. 1964)

[piranha]

One more possibility from Nevada, New York, Newfoundland, Oklahoma, Quebec, Utah, Vermont and the Yukon Territory:

Kawina sp. - ...also a few pliomerids worth looking at as well...

and just attached Pandaspinapyga... out of breath! :geek: :pic:

Kawina

Pandaspinapyga

[piranha]

Hi again Caleb,

Adding a few more cheirurid photo plates of Cydonocephalus and Xystocrania for comparison. Two pliomerid genera of Pliomerops and Pseudomera have species that are reasonably close but after evaluating further not as good a match as the cheirurids. This is getting interesting as I have discovered that Cydonocephalus is actually synonymous with Kawina. I just sent you the paper so you can research all of the taxonomic shuffling that will hopefully point in the right direction.

Looks like you have a new species occurrence that needs to be described and published...

RE: Middle Ordovician (Whiterockian) Trilobites from the Sunblood Formation,

District of Mackenzie, Canada Journal of Paleontology, Vol. 65, No. 5 (Sep., 1991)

pp. 801-824 - Author(s): James V. Tremblay and Stephen R. Westrop

[Caleb]

Thanks Piranha, I did have that paper(Sunbold Fm.) and it has been a great help with IDing some of the other bugs we've found. That Pandaspinapyga looks like a pretty good match and with it being out of the Kimmswick is the same age.

[Caleb]

Looks like you have a new species occurrence that needs to be described and published...

That's something I've wanted to do since I found my first undescribed bug. I'm just not sure how I would go about doing it since I'm not associated with any institution. Maybe I'll find a bored grad student looking for a challenge...

[squalicorax]

That's something I've wanted to do since I found my first undescribed bug. I'm just not sure how I would go about doing it since I'm not associated with any institution. Maybe I'll find a bored grad student looking for a challenge...

I could talk to Paleontology professor of mine and maybe we can set something up here in Milwaukee.