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Post by ammocarbsteve on Apr 5, 2011 3:44:54 GMT -5
I thought Joe might like a look at these as discussed....these are what we find and call regurgitates which are basically masses of organic matter some displaying parts of insects or shells, that have all ended up mashed up in a pile in some form of phosphatic blob in a nodule.... we attributed it to fish of some description, regurgitating the undigested parts of a meal.... I know sharks can do this...The problem with this idea though is if it was carried out under water... the waste material regurgitated would be very diluted and maybe even have spread out more thinly by the time it reached the bottom of the river system, and wouldnt end up in a 'localised spot ' to fossilise...so then we thought possibly lungfish in the margins or possibly even amphibians...I know amphibians very often regurgitate when frightened... maybe they could even be coprolites that have 'spread and opened' after being soaked in the slow moving margins of the river system of a levee...... the great regurgitate mystery... Heres one containing a spider, millipede bits, bivalves and an amalgamation of allsorts...and potentially one containing 2 scorpions that belongs to a friend... Whats your thoughts on these...Thanks Steve Attachments:
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Post by ammocarbsteve on Apr 5, 2011 3:46:58 GMT -5
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Post by ammocarbsteve on Apr 5, 2011 3:47:35 GMT -5
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Post by ammocarbsteve on Apr 5, 2011 3:48:14 GMT -5
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Post by ammocarbsteve on Apr 5, 2011 3:49:14 GMT -5
and the potential Scorpion body'... Attachments:
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Post by pleecan (Peter Lee) on Apr 5, 2011 4:51:21 GMT -5
Neat looking fossils Steve... I like the last fossil the scorpion body.
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Post by Joe Botting on Apr 22, 2011 23:01:36 GMT -5
Interesting things, Steve! I've only seen one good one of these myself, and that was composed of fish remains. I've always thought of them as fish coprolites rather than regurgitates (if you've ever kept goldfish you'll have seen their droppings can be pretty diffuse), and your specimens seem to bear that out a bit, as they include relatively digestible arthropod remains. They problem, as you say, is how to keep them in intect masses (whether coprolites or regurgitates), but there are a couple of options: 1) they were deposited under very quiet conditions, and bound together by bacterial or fungal material, so that when the current increased enough to deposit lots of sediment, they stayed intact. Such biofilms are known to have happened around, for example, some graptolites (http://geology.gsapubs.org/content/30/4/343.short) under different conditions. 2) The deposition of sediment was rapid enough that the structures didn't have time to break up. Once buried, they should be relatively intact until the nodule grew, I'd have thought. I reckon the key will be in the phosphatic surrounding material - if it's made of minute, but ground-up particles, then it probably was coprolite. If it's simply phosphatic mineral material, then it may well be caused by microbial growth over the remains, which makes it more likely to be a pile of regurgitated bits. Of course, it's very likely that both were there, and both have been fossilised. The third one looks like coprolite, and the fourth like regurgitate, to me. But yes, I'm guessing!  |
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Post by ammocarbsteve on Apr 23, 2011 8:16:39 GMT -5
Hi Joe... Thanks for your thoughts on these... We do like a mystery...Interesting thoughts on bacterial growth binding it toether until burial, I never considered that before....
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Post by ammocarbsteve on Apr 24, 2011 9:25:41 GMT -5
Speak of the regurgitate devil.... Heres another one from today... I'm pretty sure this one has arthropod remains in....What do you think? Attachments:
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Post by ammocarbsteve on Apr 24, 2011 9:26:14 GMT -5
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Post by ammocarbsteve on Apr 24, 2011 9:27:08 GMT -5
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