Macrasters and mortoniceras from local creek

[Shaun-DFW Fossils]

Johnson county, TX creek finds from yesterday afternoon. Unexplored section of a creek that has been productive for me with every visit. The mortoniceras arringtoni and drakei are in great shape on both sides (most of them) and only 2 of the macrasters are compressed or missing a chunk.

Edited November 9, 2023 by Shaun-DFW Fossils

[Tidgy's Dad]

Nice finds.

However, I am a little confused. You have "Drakeoceras" in your tags, but "drakei" in the post. I'm assuming that this should be drakei, a species, Is there a Drakeoceras drakei? Or is this Mortoniceras drakei?

This is also why it is a good idea to use correct nomenclature and italicise the genus and species with the genus always being capitalized and the species never capitalized.

Edited November 9, 2023 by Tidgy's Dad

[Shaun-DFW Fossils]

17 minutes ago, Tidgy's Dad said:

Nice finds.

However, I am a little confused. You have "Drakeoceras" in your tags, but "drakei" in the post. I'm assuming that this should be drakei, a species, Is there a Drakeoceras drakei? Or is this Mortoniceras drakei?

This is also why it is a good idea to use correct nomenclature and italicise the genus and species with the genus always being capitalized and the species never capitalized.

Thanks, good point! Sorry for the lack of clarity. I think there was a proposed change from mortoniceras to drakeoceras. Perhaps I should have said mortoniceras (drakeoceras) drakei and mortoniceras (drakeoceras) arringtoni. I welcome correction if I am wrong in that. Thanks for all who share their knowledge with this noob (me)!

[Tidgy's Dad]

7 minutes ago, Shaun-DFW Fossils said:

Thanks, good point! Sorry for the lack of clarity. I think there was a proposed change from mortoniceras to drakeoceras. Perhaps I should have said mortoniceras (drakeoceras) drakei and mortoniceras (drakeoceras) arringtoni. I welcome correction if I am wrong in that. Thanks for all who share their knowledge with this noob (me)!

[hadrosauridae]

Very nice finds!

 

[trilobites_are_awesome]

I love your finds!

[Shaun-DFW Fossils]

2 hours ago, Shaun-DFW Fossils said:

Johnson county, TX creek funds from yesterday afternoon. Unexplored section of a creek that has been productive for me with every visit. The mortoniceras arringtoni and drakei are in great shape on both sides (most of them) and only 2 of the macrasters are compressed or missing a chunk.

My friend Mercer did some research and it appears several of the ammonites I found are a different species than drakei or arringtoni, they’re actually mortoniceras (drakeoceras) gabrielense! This is the kind of nerdy info that makes me happy. I’ll have to keep one of them for my personal “keepers” collection. 

[JamieLynn]

Good stuff! Do you know what this one is? I have found a few similar in Georgetown Formation / Duck Creek Formation in Central Texas. I have not been able to discern what genus. 

[Shaun-DFW Fossils]

1 hour ago, JamieLynn said:

1 hour ago, JamieLynn said:

Good stuff! Do you know what this one is? I have found a few similar in Georgetown Formation / Duck Creek Formation in Central Texas. I have not been able to discern what genus. 

Thank you Jamie! I do not know for sure at this moment. I find lots of ammonites here in various life stages, so I’m guessing it’s a young mortoniceras (drakeoceras) drakei because I find those most often. The gabrielense I found occur sporadically throughout the Fort Worth formation but not all over the place, and they have 2 nodules along each side of the ridge/sephuncle 

[sixgill pete]

Great finds. Amazing, great stuff!!

[Shaun-DFW Fossils]

49 minutes ago, sixgill pete said:

Great finds. Amazing, great stuff!!

Thanks Sixgill Pete!

[Neanderthal Shaman]

Very nice

[Jared C]

so cool. Do you know which geologic formation it is?

[Shaun-DFW Fossils]

1 hour ago, Jared C said:

so cool. Do you know which geologic formation it is?

Great question! My map shows Grayson, but a geologist I trust says Fort Worth, I am not knowledgeable enough to know if these are interchangeable or separate. I also see paw paw just west of Grayson, so I have more education to undergo! Not far from Duck Creek formation

[Jared C]

19 minutes ago, Shaun-DFW Fossils said:

My map shows Grayson, but a geologist I trust says Fort Worth, I am not knowledgeable enough to know if these are interchangeable or separate

they are two different formations: Fortworth limestone being older than the pawpaw and grayson above it. I'm not as familiar with the lithology of the north texas formations, but I do know that the Grayson is usually a marl, not a limestone. 

 

What's likely the case is that though your area is mapped as Grayson, the creek cuts below the grayson and pawpaw to hit the limestone fort worth formation below it. 

[Lone Hunter]

15 minutes ago, Shaun-DFW Fossils said:

Great question! My map shows Grayson, but a geologist I trust says Fort Worth, I am not knowledgeable enough to know if these are interchangeable or separate. I also see paw paw just west of Grayson, so I have more education to undergo! Not far from Duck Creek formation

When we were talking about this I forgot to ask what map your using? And if anyone reading this can explain 'undivided' formations I would appreciate. It does get confusing in areas around there with underlying and overlapping formations and pocket map isn't 100% accurate. Sometimes I can tell by color and rock type otherwise think you have to go by associated fossils. 

[DPS Ammonite]

23 minutes ago, Shaun-DFW Fossils said:

Great question! My map shows Grayson, but a geologist I trust says Fort Worth, I am not knowledgeable enough to know if these are interchangeable or separate. I also see paw paw just west of Grayson, so I have more education to undergo! Not far from Duck Creek formation

When you use the geological map of Texas realize that the map does not often show the correct formations at the bottom of small narrow canyons because the map scale won’t allow. The formations usually are correct for the top of the canyon on either side. Go back and see if you can find typical Grayson fossils at the top of the canyon. Depending on how deep and canyon is you might encounter 1 or 2 formations below the Grayson.

[Shaun-DFW Fossils]

9 minutes ago, Lone Hunter said:

When we were talking about this I forgot to ask what map your using? And if anyone reading this can explain 'undivided' formations I would appreciate. It does get confusing in areas around there with underlying and overlapping formations and pocket map isn't 100% accurate. Sometimes I can tell by color and rock type otherwise think you have to go by associated fossils. 

I started out with the Wikipedia (I know I shudder at mentioning the name) map, but Mercer Brugler introduced me to the Mancos app, so I’ve been using Mancos. Even in creeks, sometimes I notice it seems “off.” I know not all creeks are the same depth, so I understand the variability to an extent. I find the conlinoceras in one spot showing to be deep in the woodbine, but then the other spot is fairly far into the Eagle ford shale. I assume my lack of understanding is probably my own ignorance. 

[Shaun-DFW Fossils]

8 minutes ago, DPS Ammonite said:

When you use the geological map of Texas realize that the map does not often show the correct formations at the bottom of small narrow canyons because the map scale won’t allow. The formations usually are correct for the top of the canyon on either side. Go back and see if you can find typical Grayson fossils at the top of the canyon. Depending on how deep and canyon is you might encounter 1 or 2 formations below the Grayson.

Great points/tips, thanks for explaining! I agree with you as well.

[Lone Hunter]

Try the USGS Pocket Texas Geology and see if any better though it still won't work in narrow canyon or small outcrops it's usually spot on.

[DPS Ammonite]

8 minutes ago, Shaun-DFW Fossils said:

Great points/tips, thanks for explaining! I agree with you as well.

Use the North Texas Fossils website to help with stratigraphy and fossils. Realize that the formation names may change in different parts of the area.

 

 

http://northtexasfossils.com

[Shaun-DFW Fossils]

7 hours ago, DPS Ammonite said:

Use the North Texas Fossils website to help with stratigraphy and fossils. Realize that the formation names may change in different parts of the area.

 

 

http://northtexasfossils.com

Thank you! I’ve enjoyed Lance Halls website and it’s helped me so the identification in the past, but I didn’t realize he had those maps. I found it!

[Shaun-DFW Fossils]

7 hours ago, Lone Hunter said:

Try the USGS Pocket Texas Geology and see if any better though it still won't work in narrow canyon or small outcrops it's usually spot on.

Thanks, that’s a new one for me! I like that it’s free..I saved the link as a favorite.