Help Identify Cretaceous Ammonite

[galaxy777]

Hi,

I found this beauty at lake texoma. Upper Cretaceous era, Eagle Ford I think.

Is it Oxytropidoceras?

It's in really good shape. Both sides are present.

I liked to had a coronary when it popped right out of the limestone.

It's size is 9" x 7 1/4" x 1 3/8"

[Foshunter]

It is Oxytropidoceras, nice example hard to liberate with the keel, Duck Creek Form.---Tom

Edited September 10, 2014 by Foshunter

[Ludwigia]

Nice find! Can you get it prepped?

[Stonebone]

Very nice!

[BobWill]

That should clean up real nice. The umbilicus is probably not worn and that keel is great. Most Oxi's I see are in the Kiamichi and Goodland and some Duck creek. I didn't know they were in the upper cretaceous too. There is some Eagle Ford on Texoma around Haggerman I think.

[galaxy777]

Thanks to all of you for helping me to identify it. I found this one at Preston Point right on the peninsula; is that Duck Creek?

I don't have much experience in prepping fossils yet, so didn't want to mess it up. Might have to start practicing on a partial or two.

[JohnJ]

I agree with Bob. On Preston Point, your ammonite is most likely from the Kiamichi or Goodland formation, although other formations are present in the area.

[rwise]

nice specimen....

[LanceH]

I am not aware of them any higher than Kiamichi Fm.

[galaxy777]

Thanks for pointing out the right possible formations for this ammonite. I'm still trying to wrap my head around where some leave off and others begin.

[LanceH]

Just by the shape and preservation alone I would say it's from the Goodland Formation. It looks exactly like the ones I have from the Goodland. They don't even range as high as the Eagle Ford and maybe not higher than Duck Creek if that (as far as I know). It seems as though they may have been supplanted by Eopachydiscus in the lower Duck Creek which became so dominant the lower DC is full of them.

The north Texas geo sequence of formations with rough dates (possible time overlap here and there):

Austin Chalk -

Eagle Ford shale 90-95 mya

Woodbine sandstone 95-96 mya

Grayson shale 96-97 mya

Main Street limestone - 97 mya

Pawpaw clay - 97-98 mya

Weno clay/limestone - 98-99 mya

Denton clay 99-100 mya

Ft Worth limestone 100 mya

Duck Creek Ls (never seen one yet) - 100-102 mya

Kiamichi clay (seen one species Oxy) - 102-103 mya

Goodland Ls (multiple species Oxy.) - 103-105 mya

Walnut clay (multiple species Oxy.) - 105 mya

Paluxy sandstone (?)

Glen Rose Ls (?)

The formations are exposed across north Texas with the older ones to the west and younger ones to the east. This is because the layers dip down toward the southeast toward the Gulf and so we are seeing the layers in sequence like a titled layer cake that's been sliced even across the top.

Around Kiamichi deposition Oxy seems to disappear from the record locally.

Edited September 13, 2014 by LanceH

[BobWill]

maybe not higher than Duck Creek if that (as far as I know). lower DC is full of them.

Duck Creek Ls (never seen one yet) - 100-102 mya

I've never seen one in Duck Cr either so I was surprised to see the Houston ammonite book show O. elaboratum elaboratum from that formation in Denton, Grayson and Hill Counties.

Tom, are you finding them in the Duck Creek?