Roz Posted June 11, 2009 Share Posted June 11, 2009 This fossil pic was sent to me on my AR fossil site for an ID and I don't know what it is. It was found in Newton County, Arkansas Does anyone know? It is the only pic he sent so cropped it more to show the target fossil better. Welcome to the forum! Link to comment Share on other sites More sharing options...
Nicholas Posted June 11, 2009 Share Posted June 11, 2009 Cross section of a crinoid holdfast? Link to comment Share on other sites More sharing options...
Hawkeye Posted June 11, 2009 Share Posted June 11, 2009 Ah, I've seen one of those on E-bay! It's one of those famous fossilized duck feet. If you believe everything you read, perhaps it's time for you to stop reading... Link to comment Share on other sites More sharing options...
tracer Posted June 11, 2009 Share Posted June 11, 2009 it's a print from an arkanpaw. Link to comment Share on other sites More sharing options...
RJB Posted June 11, 2009 Share Posted June 11, 2009 I have no idea what it is Roz, but it doesnt strike me as a fossil in any way. RB Link to comment Share on other sites More sharing options...
Frank Menser Posted June 11, 2009 Share Posted June 11, 2009 Definitely a fossil. That looks like part of a shell, though of what I don't know. I have seen similar fragments in Florida. Be true to the reality you create. Link to comment Share on other sites More sharing options...
Roz Posted June 11, 2009 Author Share Posted June 11, 2009 Thanks all. Will ask for more pics as I don't think it is a cross section of a crinoid holdfast but I could be wrong. I think that area of AR is Penn. Looks like a shell to me also.... Welcome to the forum! Link to comment Share on other sites More sharing options...
jkfoam Posted June 11, 2009 Share Posted June 11, 2009 Roz, I am not familiar wih the geology of newton County, AR, but the photo shows, in the upper right corner, what appears to be an impression of a crinoid columnal so that gives a clue to age. The object of interest appears to me to be broken in half showing us a cross section. And the remaining form does not resemble any invertebrate form that I am familiar with. I think Nicholas's suggestion of a holdfast fragment is as good a suggestion as any. Menser, suggested a shell fragment. I think he was alluding to the exagerateted digitation of the outter lip of a snail like Aporrhais sp. but i don't think that matches the geologic age. JKFoam The Eocene is my favorite Link to comment Share on other sites More sharing options...
Xiphactinus Posted June 11, 2009 Share Posted June 11, 2009 This is the internal mold of a crinoid. We commonly find these in the chert in the Burlington fm. If I had to bet, I would say it is a type of Physetocrinus. Link to comment Share on other sites More sharing options...
Frank Menser Posted June 11, 2009 Share Posted June 11, 2009 Menser, suggested a shell fragment. I think he was alluding to the exagerateted digitation of the outter lip of a snail like Aporrhais sp. but i don't think that matches the geologic age. JKFoam I'll be the first to say I am not an expert on Mollusks or for that matter Crinoids. But here is what I saw that I based my opinion on. First, That is not an impression, as it stands partially clear of the limestone it is locked in and it is not composed of the same material as the rock it's in. Second, the blue color is consistent with millions of shell fragments I have seen in Florida, where by the way, that very porus limestone it's sitting in is common. My thought is that It looks very much like the inside view of a bivalve, possibly a fragment of a Scallop type shell. But again, I can easily be wrong Be true to the reality you create. Link to comment Share on other sites More sharing options...
Xiphactinus Posted June 11, 2009 Share Posted June 11, 2009 Menser, suggested a shell fragment. I think he was alluding to the exagerateted digitation of the outter lip of a snail like Aporrhais sp. but i don't think that matches the geologic age.JKFoam I'll be the first to say I am not an expert on Mollusks or for that matter Crinoids. But here is what I saw that I based my opinion on. First, That is not an impression, as it stands partially clear of the limestone it is locked in and it is not composed of the same material as the rock it's in. Second, the blue color is consistent with millions of shell fragments I have seen in Florida, where by the way, that very porus limestone it's sitting in is common. My thought is that It looks very much like the inside view of a bivalve, possibly a fragment of a Scallop type shell. But again, I can easily be wrong The rock really isn't porous -- all those holes are impressions from crinoid column segments! The chert in the Burlington limestone is litterally filled with voids created from dissolved crinoids and brachiopods. You can get some really cool internal structure fossils. Link to comment Share on other sites More sharing options...
Nicholas Posted June 11, 2009 Share Posted June 11, 2009 Roz,I am not familiar wih the geology of newton County, AR, but the photo shows, in the upper right corner, what appears to be an impression of a crinoid columnal so that gives a clue to age. The object of interest appears to me to be broken in half showing us a cross section. And the remaining form does not resemble any invertebrate form that I am familiar with. I think Nicholas's suggestion of a holdfast fragment is as good a suggestion as any. That impression is what got me thinking Crinoid Link to comment Share on other sites More sharing options...
jkfoam Posted June 11, 2009 Share Posted June 11, 2009 Menser, suggested a shell fragment. I think he was alluding to the exagerateted digitation of the outter lip of a snail like Aporrhais sp. but i don't think that matches the geologic age.JKFoam I'll be the first to say I am not an expert on Mollusks or for that matter Crinoids. But here is what I saw that I based my opinion on. First, That is not an impression, as it stands partially clear of the limestone it is locked in and it is not composed of the same material as the rock it's in. Second, the blue color is consistent with millions of shell fragments I have seen in Florida, where by the way, that very porus limestone it's sitting in is common. My thought is that It looks very much like the inside view of a bivalve, possibly a fragment of a Scallop type shell. But again, I can easily be wrong Frank, I thought you meant the triangular shape of the object was similiar to the outer lip of some snails such as Aporrhais sp. I stand corrected. I have got to quit alluding (LOL). JKFoam The Eocene is my favorite Link to comment Share on other sites More sharing options...
MB Posted June 11, 2009 Share Posted June 11, 2009 It looks Batman http://www.mbfossilcrabs.com/ Link to comment Share on other sites More sharing options...
Frank Menser Posted June 12, 2009 Share Posted June 12, 2009 The rock really isn't porous -- all those holes are impressions from crinoid column segments! The chert in the Burlington limestone is litterally filled with voids created from dissolved crinoids and brachiopods. You can get some really cool internal structure fossils. Have to disagree. Crinoid sections have a very recogniseable structure which if you look at those "pores" they do not as far as I can see. The holes are irregular in shape and size. In S. Florida there are no crinoids, but the same looking kind of rock. I have seen very porus rock associated with Chert nodules in the Gainesville, FL area, the association was with echnoid fossils-but not Crinoids. One way to confirm this as either Chert or Limestone is to do a hardness test on the rock. Chert is a form of Quartz which has a hardness of 7 on Moh's scale. Limestone is much softer (unless there are quartz grains included) but should be scratchable by window glass. Be true to the reality you create. Link to comment Share on other sites More sharing options...
Frank Menser Posted June 12, 2009 Share Posted June 12, 2009 Frank,I thought you meant the triangular shape of the object was similiar to the outer lip of some snails such as Aporrhais sp. I stand corrected. I have got to quit alluding (LOL). JKFoam Didn't even know that existed... Very cool! Be true to the reality you create. Link to comment Share on other sites More sharing options...
Xiphactinus Posted June 12, 2009 Share Posted June 12, 2009 Have to disagree. Crinoid sections have a very recogniseable structure which if you look at those "pores" they do not as far as I can see. The holes are irregular in shape and size. In S. Florida there are no crinoids, but the same looking kind of rock. I have seen very porus rock associated with Chert nodules in the Gainesville, FL area, the association was with echnoid fossils-but not Crinoids.One way to confirm this as either Chert or Limestone is to do a hardness test on the rock. Chert is a form of Quartz which has a hardness of 7 on Moh's scale. Limestone is much softer (unless there are quartz grains included) but should be scratchable by window glass. Frank - I'm very familiar with the rocks from that area in Arkansas. It's Mississippian - nothing at all like the rocks in Florida. The Burlington chert looks just like this example. If you look to the left of the left-most "lobe", you'll see a small section of criniod stem. At the end of each "lobe" - you see a small split. Each of these would lead to the attachments for an arm. I don't have a good picture here at work, but note the split for two arms at each attachment point. Link to comment Share on other sites More sharing options...
Frank Menser Posted June 12, 2009 Share Posted June 12, 2009 Frank - I'm very familiar with the rocks from that area in Arkansas. It's Mississippian - nothing at all like the rocks in Florida. The Burlington chert looks just like this example. If you look to the left of the left-most "lobe", you'll see a small section of criniod stem. At the end of each "lobe" - you see a small split. Each of these would lead to the attachments for an arm.I don't have a good picture here at work, but note the split for two arms at each attachment point. I can see where you are getting at with the crinoid. There is a definite similarity. As to the limestone/chert?. I would have to see a better detailed closeup before I change my mind on that. Almost forty years of collecting in Florida has made me very familiar with the types of rock found there. It does not look at all to me like the rock your crinoid is sitting in. Nothing is as ancient as Mississipian in the entire state, however, rock with that structure is not limited to any particular era. Now you have me looking in my old boxes to se if I brought some of the rock I'm talking about up from Florida. The problem with common rock is you don't keep it and then suddenly, when you are hundreds of miles away... Be true to the reality you create. Link to comment Share on other sites More sharing options...
Roz Posted June 12, 2009 Author Share Posted June 12, 2009 Xiphactinus, with that pic I see exactly where you mean. Thanks! Welcome to the forum! Link to comment Share on other sites More sharing options...
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