Ordovician in Tennessee (Help!)

[DWhatley]

I know several people with Kindles that love them but before you order an e-book to read on the computer, download the software and try reading some of the freebies to be sure you like this medium. I was very disappointed in the few things I tried and feel that reference books might still be better in book form. It may be that a "pay-for" book can be referenced easily and would be great in ebook format but the couple of free things I played with I did not like at all.

 

[Terri]

Thanks D, if you were dissapointed I'm not going to even bother with it. Too many dollars to waste to be even remotely dissapointed!

I just heard it was snowing heavily in Atlanta, hope you get to stay home tommorrow.

 

[Terri]

I'm reading like crazy on trace fossils, and this location seems to have a lot of different types that I will post as soon as I have a better understanding of what I'm posting.

Here are two fossils I think are gastropods, just different views than I'm used to seeing? The first one is about 1.5 cm. across and the second about 1cm.

 

[DWhatley]

How do you determine a snail from a ceph fossil?

This article from the cephalopod page helps a little if I am right in understanding that each new chamber produces a visible outside marking. I can imagine it with the rings I see in a lot of the photos but can't visualize how the more ornate looking marks are a feature of an internal chamber.

 

[Architeuthoceras]

I don't see any sign of sutures, so I think you're right on the gastropods.

 

[Terri]

...and a cross-section of a gastropod, any thoughts on species?

 

[Architeuthoceras]

Just a guess at a generic assignment, Raphistomina.

 

[Terri]

Thanks Kevin, that was another of the different views, I'm not used to seeing.

 

[Terri]

Well, the pics. came out in the wrong order and the text should have come first but you'll get the idea!...Saturday was 70 and not a cloud in the sky, to top it all off an Actinoceras (my guess). I'm wondering what made the holes, they're only a mm or 2 deep, did gastropods drill holes like that?

 

[Architeuthoceras]

70? Ain't seen that for months.

Some of the holes look like they are on a freshly broken surface, can you tell if the siphuncle was broken before it got fossilized? All the septa and outer shell are missing so it was well abraded while sitting on the sea floor. Do gastropods eat calcium deposits just for the calcium? Nice fossil Terri! And as always, more questions than answers.

 

[Terri]

To my untrained eye Kevin, it looks as if it was fossilized after it was broken, maybe still attached in a few small places where some of the crystals look freshly broken. Some of the other edges on that rock do look fresh and it was probably broken up when they were hauling rock out. But then I really don't know what I'm talking about, hence all the questions... I'm going to try to post another pic. of rest of the fossil on the other rock, had difficulties posting this morning so if doesn't show up, I'll have to see what's up with my computer.

 

[Terri]

 

[Architeuthoceras]

With that new pic I can see that the holes on the broken surface aren't as round as those on the original surface, and also that the inside has had a lot of recrystallization taking place, so it was probably broken while they were quarrying.

Some of the holes on the outer surface look like they have lips around the edge, perhaps something was living in the holes rather than just drilling them to get inside.

 

[Terri]

That makes sense to me, I was just looking with a magnifying glass and noticed this, doesn't show as much as I wanted, but looks like something hollowed out that chamber..

 

[Terri]

So probably worm burrows?