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Post by tncaveres on Mar 28, 2007 21:28:23 GMT -5
This not really cave related but I told Bull I would take of a pic of this fossil for him. I always thought it was pretty cool looking.
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Post by Azurerana on Mar 28, 2007 23:18:18 GMT -5
So, what do you think it is?
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Post by jonsdigs on Mar 29, 2007 10:25:57 GMT -5
These appear to be diagonal cross sections of straight nautiloid cephalopods (squids in shells like the chambered nautilus), perhaps Actinoceras sp. Are these found in an Ordivician limestone like the Nashville Group? Straight nautiloid cephalopod with internal cut-a-way.The chambers regulated buoyancy like the ballast chambers in a submarine.
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Post by Azurerana on Mar 29, 2007 20:20:09 GMT -5
I was just curious to hear other opinions. I kept going back and forth between the X-section of a cephalopod, or some sort of graptolite on steroids (top fossil).
Straight shelled cephalopods are moderately (not extremely) common in Missouri middle Ordovician fossil-filled strata. I can't speak to TN-- but I know they are not uncommon in Kentucky Ordovician either.
I'm assuming the orginal poster is from TN; but not knowing the age or strata of the rock, it was hard to even take a shot in the dark. I'm pretty good on Ordovician and Mississippian fossils generally, but if someone asked the geology subdisciplines with which I am least familiar, oil and gas would be number 1 on the ignorance list, and fossils/paleobiology would be number two. I've got the big groups by sight, but have to look up any questions about genus and to species--fuggit it!
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Post by tncaveres on Mar 30, 2007 22:54:57 GMT -5
Yeah the pic was taken in Middle Tn . It is a huge slab of rock out in a cow pasture. A couple of other rocks near by have some other type of fossil on it. I will take a pic of it tomorrow.
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Post by paul snook on Apr 6, 2007 21:06:43 GMT -5
some one else replied that it may be a graptolite and I agree, the one below your hand looks like a graptolite but the one beside im not sure of, and I am defenatly wanting to see it in person now as well as the others, when can we go?
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Post by jonsdigs on Apr 6, 2007 23:50:32 GMT -5
Bull, They are both cephalopod fossils. They are cross sections cutting at different angles. Below are a couple of different pictures of cephalopod fossils. Graptolite fossils are much smaller. Here is a large graptolite; note the scale. I'm a geologist, teacher, and avid rockhound.
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Post by paul snook on Apr 7, 2007 10:40:49 GMT -5
i was thinking that as well but a buddie from the area wants to confirm it with me in person at the fossil, he has found some graptolites of similar size in the area, but you are correct most are small so it most likely is a cephelopod, while on the subject can you sugest any good books for better identifying, I curently have, smithsonian hand books, fossils by:Cyril Walker and David Ward any thing else would be good but suggested by a geolgist would be better,
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L Roebuck
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Post by L Roebuck on Apr 7, 2007 13:28:55 GMT -5
Here's another fossil photo to ponder. So would this possibly be a cephalopod or graptolite? This is also from Middle TN.
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Post by Azurerana on Apr 7, 2007 14:20:37 GMT -5
Jonsdigs-- see abstracts.graptolite.net/longest.html Although the small segments are undoubtably the most common, larger specimens are not unknown. To the rest of the non-geos around here--graptolites are generally trace fossils in rock--not something you can dig out with a pick or dentist's drill. The difficulty when looking at a fossil photo in a split layer of rock is when the rock has been broken through a fossil, you are looking at a cross section--sometimes a very odd non-perpendicular cross section at that. If you are looking at the actual rock, you can tell what is fossil, what is matrix, and with a little probing from a pocket knife, you can tell a trace from a preserved critter. That's not possible with a photo. '' Cephalopods can be a few inches to six feet long. Lynn-- your fossil looks like either a non-nautiloid member of the cephalopod family--called an Actinoceras, or possibly part of a large crinoid stem. Not all crinoid stems were smooth-- I've got a stem segment about 6 inches long, 1 inch in diameter, and with the roughest and variable diameter I've seen. But still a crinoid... Look at the top or bottom ends of the column. What does the cross section look like? The right side of your fossil looks like it might be just below the calyx (head) of a crinoid. It's just really hard to ID fossils from photos, because most Net photos do not have enough detail. With fossils, the devil is in the details.
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Post by paul snook on Apr 7, 2007 19:29:24 GMT -5
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Post by jonsdigs on Apr 8, 2007 10:34:07 GMT -5
What a magnificent nautiloid the first fossil is! I'd have to look at a high magnification on the second to tell.
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Post by paul snook on Apr 8, 2007 10:59:08 GMT -5
i was lucky to get it the owner had no idea it was there nor did he care as well as nor did he know what it was, when i told him he said and i quote " when was the ocean this far inland?" he was going to cover the large rock it was in with fill dirt, it was in his front yard during construction and he alowed me to cut it out, even still i would not have known about it had a buddie who knows i love fossils and rocks etc, had not shown it to me, i used it for a coffee table for a long time until i got tired of moving the heavy thing every time i vacumed, i would love to find out what specific species it is and how it ranks in size with others like it, can you offer help?
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Post by Azurerana on Apr 8, 2007 12:16:29 GMT -5
Ummm.... there are at least *two* people here with geology degrees...*|:-) If you are looking for specific species, it might do you well to ask around your caving grotto if anyone knows about fossils, since these rocks aren't easily portable. You really need someone to look at it in person if you want down to species. the Actinoceras name we've been throwing around is just down to Order. If asking at a grotto doesn't help, contact: East Tennessee Geological Society www.discoveret.org/etgs/trips/gray/gray.htm (these folks apparently 'do fossils' per there website). Middle Tennessee Gem and Mineral Society www.mtgms.org/ The Paleontology Society has a Southeastern Section, based out of UT-Knoxville www.paleosoc.org/meetings_2001.htmlIf you have a UT campus near you, you might see if they have a geology dept., with someone to help you. Two names that keep coming up when searching on Tennessee fossils are Larry Mathews (NSS member) and Harry Moore TDOT geologist-- www.state.tn.us/environment/tn_consv/archive/fossil.htmIt sounds like these two men, while not experts on Ordovician fossils, might be able to point you in a good direction. Other than that, doing a net search on Ordovician fossils, or fossil cephalopods would prove useful. www.nashvillefossils.com/fossils/fossilsbytaxon.html
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L Roebuck
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Post by L Roebuck on Apr 8, 2007 16:10:24 GMT -5
Lynn-- your fossil looks like either a non-nautiloid member of the cephalopod family--called an Actinoceras, or possibly part of a large crinoid stem. Not all crinoid stems were smooth-- I've got a stem segment about 6 inches long, 1 inch in diameter, and with the roughest and variable diameter I've seen. But still a crinoid... Look at the top or bottom ends of the column. What does the cross section look like? The right side of your fossil looks like it might be just below the calyx (head) of a crinoid. Well Heck .... I can't really see the cross section of the fossil. Thanks for the info and taking a look at the photo Az!
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Post by Azurerana on Apr 8, 2007 16:39:32 GMT -5
Well Heck .... I can't really see the cross section of the fossil. Thanks for the info and taking a look at the photo Az! just take an exacto knife, or similar sharp pointy steel object, and dig around a little--not much--an 1/8 inch or so will do. Dig into the rock, not the fossil, and use a spray bottle to clear away the rock dust. If you get a sun ray pattern, or see something which looks like this: ------------o---------- down the middle of the end of the fossil, chances are it is a crinoid. If not--well, it's not. I've never seen a cephalopod with these sort of segment joins. Crinoids are echinoderms (related to starfish. Cephalopods are mollusks. Since your segments are not so curved as with the other photos, that's why I'm suspecting it might not be a cephalopod.
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Post by tncaveres on Apr 9, 2007 13:38:52 GMT -5
Thanks for all the replies guys. Hey Bull we can go just about any day I am not on shift.
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Post by gillip on Jun 12, 2007 20:21:39 GMT -5
I just came across this post. I would have to agree that the pictures from tncavers and the first pics by Cave Bull are Cephalopods. In tncavers pictures, it is not so clear as to what kind. The fossil below his hand is clearly a cross section, with the darker portion being the siphunclar deposits. Cameral deposits are not visible. (The siphuncle is a bouyancy contol mechanism, it is thought that the siphuncle is used to control pressure withing the spaces between septa and possibly fill them with water. The siphuncle is shown in pink on the cutaway illustration that jonsdigs posted. Cameral depostis occur on the septa, which are the walls seperating the different chambers of the shell). With these features, it is hard to narrow it down between subclasses Nautiloidea, Endoceratoidea, and Actinoceratoidea. It could well be Actinoceras sp., which are found in the Ordivician limestones in Kentucky. Actinoceras sp. generally have cameral and siphuncular deposits The fossil to the left of the hand appears to be the outside of the shell. It is very hard to narrow it down from the exterior of the shell. It could be any of the subclasses listed prior.
The pictures Cave Bull posted are definately Subclass Actinoceratoidea and almost certainly Actinoceras sp. Cameral deposits are chatacteristically present. Segments of the sphuncle are inflated between septa and the siphuncle contains the characteristic endosiphuncular deposits. Actinoceras sp. have been reported as long as 15 feet, but 3 to 5 feet seems a fairly common size for . The narrow end would have tapered to a point at one time, althought the end may have been lost ante-mortem. You have part of the phragmacone (living chamber at wide end), but much of it is missing. This is very common because once the organism dies and there is no flesh in the living chamber, it is very easily crushed. In some cases,especially with deposition in deep water, the decomposing flesh actually explodes the phragmacone. I can't venture a decent guess at the last two pictures Cave Bull posted. If I had a close-up, particularly of the end, it would be easier to guess. Also, if you have any HCl arround, put a drop on the fossil and see if it bubbles. If not, it is likely silica and I would guess sponge. It could also be a icnofossil (trace fossil) like a burrow being filled, but thati is unlikely as it appears to be parallel with bedding. It could possibly be a corral or a bryozoan. The rock it is on looks strange, almost like a conglomerate.
The picture Lynn posted is very interesting. At first I thought Archimedes (Bryozoan) with fronds missing, but the whirls are too smoth. Then I thought nautiloid. Then I thought crinoid. So many possibilities. At the right end of the photo, it appears there is a orthoceratitic suture. At the same time crinoids sometimes have patterns on the stem segments. If it is a crinoid, there should be a hole centered in the end. Also, a crinoid stem segment is a single calcite crystal and should cleave accordingly. If it is some kind of nautiloid, the end should be concave. The siphuncle may be centered or off-center, which would futher aid in idenifying the fossil. A picture of the end would greatly aid in identifing this fossil.
It has been a long time since I have taken paleontology. At one time I was very failiar with Carboniferous cephalopods here in Arkansas, but working as a hydrologist has blurred my memory. It is always difficult to positively identify fossils from pictures, but I can always venture a S.W.A.G.
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Brian Roebuck
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Post by Brian Roebuck on Jun 13, 2007 21:27:27 GMT -5
I'm not sure Lynn can take a photo of the end of her fossil for you to inspect. We'll take a look at it and see though. Thanks for the great response!
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L Roebuck
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Post by L Roebuck on Jun 14, 2007 19:32:27 GMT -5
Not much detail so I don't think this will helpful - but here's a photo of the end of the fossil anyway.
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Post by gillip on Jun 14, 2007 20:15:55 GMT -5
It looks like that pesky rock is getting in the way. With your permission, I will email a copy of the picture you originally posted to Dr. Manger at the University of Arkansas. He is a top notch paleontologist with an amazing ability to remember obscure information. He would likely be able to identify it. Also, since it is from middle Tennessee, does that make it Ordivician in age? From what you can see of the end, it does not look like there is a thin shell, so I would lean toward some kind of crinoid.
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Brian Roebuck
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Post by Brian Roebuck on Jun 15, 2007 5:27:48 GMT -5
I'm pretty sure it is OrdOvician ;D age limestone around here.
Thanks!
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