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Looking For Assistance Identifying Exact Species of Mortoniceras Ammonites


freerangetraveler

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Hello all,

 

I’m hoping the braintrust here can help me identify the species of two Mortoniceras Ammonite cast fragments I found this past Spring.

 

They were located in an alluvial river deposit that runs through the Duck Creek and Weno Limestone/Pawpaw formations of Northern Tarrant County in north Texas.  If my reading is correct, they should be mid-Cretaceous period and approx. 100 to 95 mya, but I would love someone to check me on that as well.


The cast in the first three pics is fairly well defined with a prominent siphuncle ridge.  The second cast (last four pics) actually has a small geode I discovered while cutting these down to display.

 

I appreciate any help the group may be able to lend and I hope you all have a great weekend!

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Edited by freerangetraveler
Corrected tag formations
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  • freerangetraveler changed the title to Looking For Assistance Identifying Exact Species of Mortoniceras Ammonites

    Tim    -  VETERAN SHALE SPLITTER

   MOTM.png.61350469b02f439fd4d5d77c2c69da85.png      PaleoPartner.png.30c01982e09b0cc0b7d9d6a7a21f56c6.png.a600039856933851eeea617ca3f2d15f.png     Postmaster1.jpg.900efa599049929531fa81981f028e24.jpg    VFOTM.png.f1b09c78bf88298b009b0da14ef44cf0.png  VFOTM  --- APRIL - 2015  

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Could we get a straight on view of the ventrum, please? It resembles the Weno ammonites on the top left here, but it’s hard to say. 
 

Also, the geode is really cool! Really makes it great for display. :ammo2:

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49 minutes ago, Heteromorph said:

Could we get a straight on view of the ventrum, please? It resembles the Weno ammonites on the top left here, but it’s hard to say. 
 

Also, the geode is really cool! Really makes it great for display. :ammo2:

Thanks for the reply!  I’ll get some additional photos as soon as I get home.

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2 hours ago, Heteromorph said:

Could we get a straight on view of the ventrum, please? It resembles the Weno ammonites on the top left here, but it’s hard to say. 
 

Also, the geode is really cool! Really makes it great for display. :ammo2:

Here’s a few more straight on photos…. Thanks again for the help!

C7FF7411-81A7-42D9-9EF6-BA1A1D798F00.jpeg

2DF428A2-AE5E-4553-882B-8CAB4D6B0864.jpeg

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Mortoniceras (Subschloenbachia) rostratum seems like a reasonable match. 

 

However, since it is so fragmentary and weathered I would personally just stick with Mortoniceras sp.

 

See: https://digitallibrary.amnh.org/bitstream/handle/2246/3243//v2/dspace/ingest/pdfSource/nov/N3236.pdf?sequence=1&isAllowed=y

 

https://www.researchgate.net/profile/Andy-Gale/publication/248573174_Upper_Albian_and_Lower_Cenomanian_ammonites_from_the_Main_Street_Limestone_Grayson_Marl_and_Del_Rio_Clay_in_northeast_Texas/links/5eb3bef3299bf152d6a1db21/Upper-Albian-and-Lower-Cenomanian-ammonites-from-the-Main-Street-Limestone-Grayson-Marl-and-Del-Rio-Clay-in-northeast-Texas.pdf?origin=publication_detail

E74781E5-4904-4B03-BAA8-2B4E7D6842CE.jpeg

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Without well defined sutures the species is probably going to be a SWAG at best.  But M. rostratum does look like a strong contender.  Personally I am really happy when I can even get an ammonite to genus level identification.

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