freerangetraveler Posted November 26, 2022 Share Posted November 26, 2022 (edited) 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! Edited November 26, 2022 by freerangetraveler Corrected tag formations Link to comment Share on other sites More sharing options...
Fossildude19 Posted November 26, 2022 Share Posted November 26, 2022 @Uncle Siphuncle @Heteromorph @erose Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 __________________________________________________ "In every walk with nature one receives far more than he seeks." John Muir ~ ~ ~ ~ ><))))( *> About Me Link to comment Share on other sites More sharing options...
Heteromorph Posted November 26, 2022 Share Posted November 26, 2022 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. Link to comment Share on other sites More sharing options...
freerangetraveler Posted November 26, 2022 Author Share Posted November 26, 2022 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. Thanks for the reply! I’ll get some additional photos as soon as I get home. 1 Link to comment Share on other sites More sharing options...
freerangetraveler Posted November 26, 2022 Author Share Posted November 26, 2022 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. Here’s a few more straight on photos…. Thanks again for the help! Link to comment Share on other sites More sharing options...
Heteromorph Posted November 26, 2022 Share Posted November 26, 2022 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 2 1 Link to comment Share on other sites More sharing options...
freerangetraveler Posted November 27, 2022 Author Share Posted November 27, 2022 Really appreciate the info, Heteromorph! Thank you! 1 Link to comment Share on other sites More sharing options...
erose Posted November 27, 2022 Share Posted November 27, 2022 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. 2 Link to comment Share on other sites More sharing options...
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