Fox Hills Formation Trip Report 6/19/21

[Thomas.Dodson]

The weather was nice so I decided to get out to a couple sites that were on my list. The first site is the site where a friendly pocket gopher throw up fossils at an otherwise barren spot. Only one pocket gopher mound had fossils. The nearby ones apparently never made it to the layer of Fox Hills strata, even the ones within a few feet of this one. 

 

An unassuming site.

The fossiliferous pocket gopher mound.

This time the conditions were fine for sieving so I proceeded to sieve this gopher's pile. Lots of shell fragments but also some more complete stuff. I rarely use my sieves in North Dakota because most sites don't have loose fossils like this.

A little Pachymelania insculpta in the sieve.

 

A bigger one.

This poor guy was hiding out in the mound and got hit by accident as I was scooping soil. He seemed to recover.

 

It didn't take long to sift the whole mound at which point I took the sorted fossils, labeled them, and moved onto a site I went to the last time I was in the area. I never finished surveying the rest of the property so I wanted to come back to make sure there wasn't anything more significant than last time. There was in fact.

 

Large Mactra warrenana were common in the salt and pepper sandstone outcrop I discovered. These ones are about 3 cm across.

The iron stained fossils stood out quite a bit.

Lower in the horizon were more outcrops of that shale and claystone, becoming progressively darker towards the base. I only saw very small shell fragments in these.

 

[Thomas.Dodson]

Fossils from the pocket gopher mound after washing.

4 more Fox Hills shark teeth. These all appear to be Carcharias samhammeri.

Fish centrums. Something about these messed with the camera so I had to jack the exposure up high in editing. Need a scope camera.

Nuculana sp.?

Pachymelania insculpta.

Cryptorhytis flexicosta?

Euspira obliquata

Indeterminate at the moment.

Primarily Crassostrea, Corbicula, and Tancredia americana.

 

From the second site:

Something different. Looking forward to seeing what this is after prep.

This is likely Cardium whitei, which would be my first specimen of it.

Various little gastropods ranging between 3-5 mm. Generally internal molds. Probably mostly Graphidula sp.

A negative and some outer shell of a Drepanochilus evansi, showing the fancy wings of the species.

Mactra warrenana

Tellinimera scitula

Partial Gastropod? Needs prep work.

 

[Opabinia Blues]

Very nice! I'm going to have to try and make it out to collect on the Fox Hills Fm. sometime this summer. Will probably just pick up some invertebrate stuff on a nice patch of BLM land not too far from my house, but I'll have to check my maps to see what's out there. Love the shark teeth!

[jpc]

I like the pelcian-foot type snails.  They are pretty common in the Pierre Shake aorund here, but to get the fancy 'wings' is a bonus.

[Thomas.Dodson]

22 minutes ago, jpc said:

I like the pelcian-foot type snails.  They are pretty common in the Pierre Shake aorund here, but to get the fancy 'wings' is a bonus.

I like them quite a bit. Every now and then I'll get one in a concretion with the wings intact, usually from the Trail City Member concretions.

[Ludwigia]

Sure must be nice to have a 4-footed assistant