Texas Cretaceous ID Help please

[JamieLynn]

Two fossils found at separate sites in Central Texas that look similar enough to me to think they are the same? Any thoughts on what this might be an impression of? Doesn't seem to correspond to any shell or urchin I know of. Thank you for any information!  

[Heteromorph]

They are pretty weathered specimens, but some closer pictures at multiple angles and information on what formation(s) this came from would be needed to get a better chance at an ID. That said, from what I can see they are probably either from bivalves or ammonites. If ammonites then compare with Elobiceras, a Mortonicerine genus of ammonites known from the Albian Kiamichi and Duck Creek formations of West, Central, and North Texas, as well as Angola and Nigeria, among other countries.

 

From what I know there are around 4 Elobiceras species in Texas. The most common Texas species is Elobiceras (Craginites) serratescens which is reported (in a not all-inclusive list) from the Albian of: 

 

Bell County, TX

Bosque County, TX

Cooke County, TX

Grayson County, TX

Hill County, TX

McLennan County, TX

Pecos County, TX

 

Emerson & Akers 1994 also list E. angustum, E. arietiforme, and E. flexicostatum as being species rarely found in Texas. Be advised that Emerson & Akers 1994 is known for its sometimes dubious taxonomic information. 

 

I would guess that these would probably Elobiceras (Craginites) serratescens since that is the most common Texas species.

 

Here are some pictures of the genus in general and of multiple Texas Elobiceras (Craginites) serratescens in particular:

 

FIG 1: A, Mortoniceras (Mortoniceras) pricei (Spath, 1922), OUM KZ23524, 278.4 m, pricei Zone. B-E, Elobiceras (Craginites) newtoni Spath, 1925. B, OUM KZ23735; C, OUM KZ23690; D, OUM KZ23692; E, OUM KZ23708; all267.9 m, pricei Zone. A, C, E, 1; B, 2.

 

FIG 2: A-J, Elobiceras (Craginites) newtoni Spath, 1925. A, OUM KZ23571; B, OUM KZ23591; C, OUM KZ23706; D, OUM KZ23602; E, OUM KZ23560; F, OUM KZ23607; G, OUM KZ23718; H, OUM KZ23572; I, OUM KZ23699; J, OUM KZ23557.AeC, EeJ are 1; D is 2.

 

Figs 1-2 specimens all from France. Pictures from pages 22-23 of this paper.

 

FIG 3.

 

FIG 4.

 

FIG 5.

 

FIG 6.

 

Figs 3-6 specimens are both Elobiceras (Craginites) serratescens from the Duck Creek of Bosque County. Pictures from Keith Minor’s website.

 

More pictures of Elobiceras (Craginites) serratescens here, and more information on the subgenus Craginites (or genus? Taxonomy is confusing) on page 4 here.

[erose]

Look at Trigonid bivalves. Pretty sure that is what the top one is. 

[JamieLynn]

The larger piece was found just north of San Antonio on 281 and I sadly cannot remember where I found the other, but somewhere around Hays County in the Hill Country.

[erose]

1 hour ago, JamieLynn said:

The larger piece was found just north of San Antonio on 281 and I sadly cannot remember where I found the other, but somewhere around Hays County in the Hill Country.

Yep. Glen Rose Formation (Early Cretaceous) and I'm pretty sure the larger one is the imprint from one of the more decorative Trigonia species. The smaller piece has similar characteristics but is just a bit to scrappy to say more.

[JamieLynn]

thank you!!