Trinity River tiny ammonite

[Creek - Don]

Is this called ammonite or another name for these specie?   I found these at Dallas Trinity river grey clay / shale layer.   I think these are upper cretaceous Austin chalk formation. 

[FossilDAWG]

These are ammonites, possibly Collignoniceras woollgari.

 

Don

[Creek - Don]

Thank you FossilDawg

[Uncle Siphuncle]

Agreed.  I’ve found these in the Eagle Ford Grp.

[doushantuo]

 

NB.:notice the correct spelling of woollgarii

C,D in the figure : slender morphs

Richard Reyment and James Kennedy:Evolution in morphometric traits in North American Collignoniceratidae(Ammonoidea,Cephalopoda)

Paleontological Research,v.5,1/2001

 

 

 

 

reymentpalres2001collignonict ammonit5_45.pdf

[DPS Ammonite]

This looks like a species of Prionocyclus that occurs in the organic shale in the upper part of the Arcadia Park Formation. Collignoniceras woollgardi usually occurs lower in the section in the Kamp Ranch Member which is a limestone with lots of teeth and inoceramid calcite prisms. The rock looks like it is shale and is not from the Kamp Ranch Member. I found a similar ammonite identified as Prionocyclus bosquensis by Jim Kennedy.

 

 

[Creek - Don]

Dps. dark layer below the slate layer was where I found these.

[FossilDAWG]

I'd always be inclined to go with the knowledgeable local collector (DPS Ammonite) over the guy (me) who has only read about things but never actually collected that site.  Anyway Prionocyclus and Collignoniceras are very similar, and I did say "possibly".

 

Don

[doushantuo]

CreekDon,that's a hugely photogenic spot!!!!

Great pic!

[Creek - Don]

Thanks. 

[Mark Kmiecik]

Nice finds. Thanks for the photos.