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Ammonites huGE


raindaddy

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Nice find. If you would like an identification of the species, could you provide a photo of the keel (edge view)? Perhaps one of our ammonite experts from San Antonio can weigh in (@Uncle Siphuncle ?). 

...How to Philosophize with a Hammer

 

 

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First step is to ascertain geologic formation.  If these are San Antonio finds, my first guess based on general features of the specimens and amount of exposure would be Austin Chalk, but we also have Lower Cretaceous ammos pop up in the more sporadically exposed Georgetown formation.  I don't have my references in front of me, but the row of umbilical nodes on each rib is the first diagnostic feature that jumps out at me.

 

Have a look at this zoomable geomap and let us know what formation you were hunting (no need to disclose your site specifics publicly).  From that point we can try to narrow it down to a genus.

 

https://www.twdb.texas.gov/groundwater/aquifer/GAT/san-antonio.htm

Grüße,

Daniel A. Wöhr aus Südtexas

"To the motivated go the spoils."

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Nice specimen!

“...whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been and are being evolved.” ~ Charles Darwin

Happy hunting,

Mason

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Thanks for posting these and welcome to the forum from a North Texan. At first I thought the one still attached to the rock was the impression where the lower one came out of the matrix but from the shadows it looks convex like the other one. They don't look like the same kind of ammonite unless there is a lot of wear because the tubercles (row of bumps) on the umbilical margin that Dan mentioned do not appear on the top one. If he doesn't recognize it I won't attempt an ID but it might help to send us another photo showing the profile like Kane suggested. That would be looking from the direction of the red arrow in this cropped image. That would tell us the shape of the whorl which can be diagnostic. That might help with the top ammonite too. Photograph the side covered up by your right hand from the edge.

 

192747353.jpg.6f36f10f45872129f9e97a2c6453defb.jpg

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Many moons ago, I wrote up something to help people decipher the formations around San Antonio.  See below.

 

 

 

Grüße,

Daniel A. Wöhr aus Südtexas

"To the motivated go the spoils."

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Just out of curiosity where was San Antonio listed as the source area for the fossil in this string? Looked this over several times. I have noticed that when folks list their location as "US" the pin on their home page shows the middle of the country. Perhaps "Texas" shows up near San Antonio? Wouldn't be the first time I missed a detail!

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I looked on the Geomap, as there are tons of ammomnites laying in the shale visible!!!!

Kdu seems to be where @BobWill also near the site was this fossil.

 

19420402_10209483032099899_682976787327744032_n.jpg

still cant figure this one.

19554263_10209486214299452_8650032078102291229_n.jpg

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On 6/21/2017 at 8:27 AM, Uncle Siphuncle said:

First step is to ascertain geologic formation.  If these are San Antonio finds, my first guess based on general features of the specimens and amount of exposure would be Austin Chalk, but we also have Lower Cretaceous ammos pop up in the more sporadically exposed Georgetown formation.  I don't have my references in front of me, but the row of umbilical nodes on each rib is the first diagnostic feature that jumps out at me.

 

Have a look at this zoomable geomap and let us know what formation you were hunting (no need to disclose your site specifics publicly).  From that point we can try to narrow it down to a genus.

 

https://www.twdb.texas.gov/groundwater/aquifer/GAT/san-antonio.htm

 

19149338_10209409232494955_8194364362246033837_n.jpg

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This looks to be "Silex", as we used as term here in Europe.

 

19554263_10209486214299452_8650032078102291229_n.jpg.bead56600cd84ad6f22c43ef273f6070.jpg.951ad830ceeeca5c260957f148e59c7e.jpgLithics-MB36-lg.jpg.bdd88b10984853302290fba9b6bd79f1.jpg

second picture from here

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ipost-22-0-69010400-1423163347.jpg.4b7eb960d8cfff67a14769b771fa0b6d.jpg

near Mcallister Park, in a ditch, or runoff, behind some neiborhoods. there are at least 3 more that i know exposed to the surface area. 

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