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verydeadthings

Unknown Chert Gravel Fossil, Devonian Or Mississipian, Louisiana

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verydeadthings

I have been collecting chert gravel fossils from the Bogue Chitto river near Franklinton, LA off and on for the last couple of years. These fossils come from the Citronelle Formation, which is Pliocene in age, and contains mostly unconsolidated sands and silts, as well as rounded chert river gravel which contains paleozoic fossils. The age is poorly known, as far as I am aware, and probably contains fossils of very different age. The most reputable source I have found on the subject was mentioned in an earlier post in the Louisiana section of the forum: (http://www.msgravel.com/assets/1312/Rocks_and_Fossils_Collected_from_MS_.pdf), but I'd be happy to learn more on the subject. According to the link, they range in age from the Devonian to the Mississipian. From my experience, crinoid fossils are the most abundant. Tabulate coral, horn coral, bryozoans, and brachiopods are less common. I just posted some of my finds to the Louisiana section of the forum: (http://www.thefossilforum.com/index.php?/topic/39199-paleozoic-chert-gravel-fossils-from-bogue-chitto-river-washington-parish-citronelle-formation/)

I have two finds in particular, however, that have stumped me. The first looks like a shark tooth, but is just an outline, and has been worn down. I think this one may be a pseudofossil. The second is more interesting. I will post a couple of pictures and then a higher quality one in a second post. Superficially, it reminds me of a cross section of a tree seed, but I don't think that's a possibility, considering all the other fossils are marine and paleozoic in age. It is bilaterally symmetrical, so perhaps a chordate or arthropod? I really have no clue. Sorry for the picture quality, I need a better camera :) Let me know what you think!

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post-1391-0-10212000-1374530075_thumb.jpg

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post-1391-0-23978900-1374530418_thumb.jpg

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verydeadthings

Here is a slightly better picture of the second fossil:

post-1391-0-67305600-1374530645_thumb.jpg

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Auspex

Your pseudo shark tooth is pretty neat; it could be something, but I cannot envision what.

Likewise the other piece, it could be a section through a fossil something, but my mental CT Scanner isn't giving me any solid hits.

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PA Fossil Finder

First looks like a thresher shark tooth. If you have Cenozoic sediments this is possible (And remember, it could have come from a formation upstream). Second I have no idea but it looks cool.

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Oxytropidoceras

The second specimen is an odd-shaped piece of chert with the impression (external mold) of the articular facet of an elliptical internodal columnal from a crinoid stem. The first fossil appears to be a cross-section of a very poorly preserved brachiopod. The lines on the chert pebble are where the pebble has has been preferentially etched by weathering along the shell of of the fossil.

A revelent web page is "Gravel Fossils" at http://web.archive.org/web/20081204120932/http://www.intersurf.com/~chalcedony/gravel1.html , which is part of http://web.archive.org/web/20081220233841/http://members.cox.net/pyrophyllite/lafossil1.html

Yours,

Paul H.

Edited by Oxytropidoceras

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verydeadthings

Thanks everyone, and in particular Paul H, after looking around the web a bit I agree with you. The second fossil looks very similar to this elliptical columnal (http://www.paleosoc.org/Crinoids.pdf). I'll just pretend the first one is a shark tooth :)

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