Fox Hills Formation of North Dakota

[Thomas.Dodson]

And the finished piece. Using the first photo as reference they are, from left to right, Hoploscaphites nicolleti, an immature Discoscaphites gulosus microconch, and a adult Discoscaphites gulosus microconch. The various bivalves are Pteria nebrascana with some assorted Limopsis striatopunctatus and corbulamella inornata.

 

[Ludwigia]

Excellent work with a fine end product!

[FossilDAWG]

Nice!

 

Don

[Thomas.Dodson]

Got some new Fox Hills species in my collection so I wanted to post them here in addition to the trip report. From the brackish Unnamed Members of the Fox Hills Formation.

 

Corbicula cytheriformis

Pachymelania wyomingensis (tuberculate) and Pachymelania insculpta (subdued ornamentation)

Anomia micronema.

 

 

[siteseer]

That's is an awesome matrix piece.  You should post that in the associations thread.

 

 

[Wrangellian]

Thanks for posting this informative guide. Lots of drool-worthy finds there.

I see a lot of similarities to my local Santonian here on the West Coast and your Graphidula looks suspiciously like a type of snail I have found here, so I may have an ID now (to genus).

[Thomas.Dodson]

5 hours ago, Wrangellian said:

Thanks for posting this informative guide. Lots of drool-worthy finds there.

I see a lot of similarities to my local Santonian here on the West Coast and your Graphidula looks suspiciously like a type of snail I have found here, so I may have an ID now (to genus).

That would be very interesting as to my knowledge Graphidula has never been described from the West Coast. There seems to be a debate as to migration occurring North or South but Graphidula is views as restricted to the interior seaway. J. Mark Erickson from Gastropoda of the Fox Hills Formation (Maestrichtian) of North Dakota (1971) on Graphidula migration and origin: "No similar form has, to my knowledge, been recorded from the approximate correlative strata of Vancouver Island or northern California where other "boreal" forms from the Fox Hills fauna seem to have existed."

 

I'm reminded of some figures discussing probable origin and range of species in Erickson's Revision of the Gastropoda of the Fox Hills Formation (1974). I've never found a digital version of this but here's some quick pics of the figures from my hard copy. You're probably aware of the Vancouver Island references but if you're not I can pull them from the References Cited for you. 

 

[Wrangellian]

What I've got may be Anchura, but from what I can tell Anchura should have a 'wing' and none of the snails I have found show any sign of a wing. I've got some that look identical (as far as my non-specialist eye can tell) to pics 3 and 4 in your post with Graphidula. It may be a new occurrence.

I wonder just how many species or genera (not just snails) exist in both your location and mine, in the same aged rock, and how many are unique to each side, and why. I know that no scaphites have ever been found here, but if they were swimmers why would they have not found their way here as other less-mobile types seem to have (though maybe those taxa had planktonic young)? These questions may have been answered but it's not at my fingertips.

[DavidN]

Thanks for the great photos, especially of the N Dakota ammonites. I have collected ammonites extensively in Montana for over 50 years, but the youngest marine exposures there (Bearpaw Fm and Pierre Shale) extend up only into the basal Maastrichtian. I would love to collect ammonites in the still younger Fox Hills Fm of the Dakotas. However whenever I look into this possibility I keep finding warnings that all the decent localities are on Indian reservations which are completely closed to collecting. Is this true, or are there still areas where Maastrichtian age ammonites can be legally collected? I'm not trying to extort locations from anyone, only seek general advice on whether there are still legal possibilities in the Dakotas.

Thanks for any response you might have.