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Mike  Olive

Conical Gastropod?

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Mike  Olive

Hello, All:

I'm a new member, live in Colorado but, mostly collect fossils on the family ranch in central Texas near Bandera. The rock there is lower Cretaceous limestone. However, I'm mainly interested in some (Edwards Formation?) chert nodules that are scattered here and there all over the ranch. Some of the nodules have fossils.

I've looked around the Fossil Forum site and I'm very encouraged. There seems to be lot of expertise, covering many types of fossils. Great. I've been able to identify some of my chert fossils but, not all, not by a long shot. Attached photos show a fossil conical marine gastropod (possibly, genus Nerinea or, Turritella?) that's pretty common on the Olive ranch. I've found dozens of them but, I don't know what the heck I've got. Any ID help would be greatly appreciated. Thanks.

Mike Olive

Boulder, Colorado

post-14214-0-69736700-1390065757_thumb.jpg

post-14214-0-37028200-1390065760_thumb.jpg

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RyanNREMTP

Closest I can find in my books is Volutomorpha. But it's hard to tell exactly from an impression.

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dinosaur12lee

I think it might be a shell imprint of maybe conch???

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Auspex

I think you are on the right track with Turritella (but which one???). Compare here: LINK

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Herb

Closest I can find in my books is Volutomorpha. But it's hard to tell exactly from an impression.

I believe also that it is a species of "Volutomorpha.post-2520-0-04671900-1390336303_thumb.jpg

Edited by Herb

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Mike  Olive

Thanks, guys, for the help. I apologize for my photos. I know they aren't the best, and I'm working on that.

But, I have to disagree here. I have dozens of these chert fossils featuring the same small, slender, high, turret-like gastropod. And I don't think it's Volutomorpha. First, the shape is wrong, my fossil doesn't have the bulb-like morphology seen in Volutomorpha. Further, the beaded ornamentation isn't identical. Each whorl of my one to 3 inch turreted fossils features a sequence of columns or pillars, these columns being composed of, usually, four beads. As the columns curve around, each is in a vertical line with the columns in the whorls above and, below. The whole thing presents itself almost like an echo of graceful marble columns from ancient Greece, having different levels, curving around a forum. Of course, being chert, it's silica dioxide, not marble but, the resemblance is there.

Anyway, as always, I appreciate all ideas that come my way. Tuning into The Fossil Forum is like taking a course on fossils. I'm learning a lot. Thanks. --Mike Olive

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Taogan

Looks like a Cerithiid, if it was European I'd say Exechocirsus, but I haven't been able to find out if that genus is present in the USA.

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elcoincoin

+1 on cerithiid

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Mike  Olive

Yeah, a cerithiid like Exechocirsus is an interesting idea. I looked over some photos of European examples and, it is pretty close. But, so far, I am unable to find good proof that Exechocirsus occurs in Cretaceous North America. It's a good lead, I'll continue looking....

Mike Olive

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Herb

here is a comparison photo of your imprint with a Volutimorpha that I have.post-2520-0-14769300-1392075740_thumb.jpg not perfect but pretty close.

Edited by Herb

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Mike  Olive

Thanks, Herb, for showing me the Volutomorpha comparison. You're right, it does make a pretty good fit. These last few days, I have been going over my dozen or so good examples of this fossil. There is a lot more variation than I remembered. Some of the conical spires are, indeed, very slim but, others are are much fatter. And, the beaded pillars do not, necessarily, form a continuous rib up and down the fossil. In some fossils, within a given whorl, each line of beads, each rib, is off-set from ribs in the whorls above and below. I don't understand all this variation. I'm gonna have to take a couple steps backwards, and rethink this. Thanks, again.---Mike Olive

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Uncle Siphuncle

the external molds look consistent with what i've found in edwards limestone cobbles. but i'm not seeing what looks to be chert, common inclusions in the edwards, at least in viewing the pix on my phone.

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