Cretaceous Gastropod?

[JamieLynn]

Found this odd little fossil in the Texas Hillcountry. I've never seen anything like it- I suspect it's a gastropod, but havn't been able to find a picture similar to identify. I first thought it was a tiny crinoid, but the segments are diagonal and at one end, the segments reverse their direction and go the other way! Any thoughts?

[ted coulianos]

looks like a section of crinoid columnal, distorted, bisected, & worn away; surrounding matrix has lots of circular crinoid segments, so my first impression is that you have a piece of crinoidal limestone & not a mollusc. hope this helps.

[Auspex]

I vote for gastropod; one of the Nerinea's.

[JamieLynn]

what is interesting and odd to me is the way the spiral sections reverse direction.....

[Missourian]

what is interesting and odd to me is the way the spiral sections reverse direction.....

That made me think of a high-spired gastropod being sectioned off at a slight angle, but then I'd expect the transition to be more gradual. Hmmm....

[Auspex]

It's an oblique bisect; the small end of the spire is at the top of the picture, and the plane of section dives down from bottom to top. See the single light circle near the top? this is the point where the plane descends past the midpoint.

[Herb]

It's an oblique bisect; the small end of the spire is at the top of the picture, and the plane of section dives down from bottom to top. See the single light circle near the top? this is the point where the plane descends past the midpoint.

What he says.

[JamieLynn]

haha!! Yeah, what he said. Thanks all!!

Edited March 14, 2013 by JamieLynn

[BobWill]

I agree except I think it's more of an abrupt drop where the rock has broken away and we see the sutures on other side rather than a straight slice the whole way through. But at first I couldn't understand why it seemed to taper so slowly. The whorls are thicker toward the aperture but about the same length side to side making the fossil sides look almost parallel. See if this makes sense. Maybe most of the shell is still under the matrix on the large end with only the closest surface broken away and conversely most of the shell is eroded off at the apex end leaving only a small slice of the outer edge of the fossil. Of course a snail with that many whorls is expected to have a high spire shape but it just seems like it should taper faster.