Predation on Trilobites

Hmmmmm; a controversy developing; what side of the fence shall I sit on :mrgreen:

I like the idea of vomit; the mouth is generally larger than the anus (I'm not an expert on such matters!!!!!), and the anus tends to be rather thin walled, so perhaps vomiting out hard parts through the large mouth is a better idea than squeezing them out of a small, tiny hole, and ripping something.

I like the idea of the assemblage being an unatural collection of bits and pieces around a sponge/bit of something soft.

It could have been a sneeze, or a wet far.. (ooops, flatulence).

Is fossilised vomit just plain-old 'vomit', or does it have a sexy title as turd has in coprolite?
I've just found out there is indeed a technical name for fossilised vomit, it is regurgitalite, so both Um...and Kevin .. were quite close!

Very interesting theory there Clem, could be possible, the thing could have swam and spun as it shat leaving a ring shape. I certainly cannot doubt it, you probably know as much about anomalocaridid butts as I do, and that sounds plausible to me! Kevin, I suppose that is possible though the shape is really quite regular, unfortunately it is less clear in the posted photo than actually looking at it in daylight. The ring is a light brown colour and quite clearly defined. How exactly do you think the fragments would accumulate around algae and stick there? Would one expect fragments to be less ground up? It's quite a mixture in there....I suppose if one had a microscope one could examine the fragments for traces of damage caused by predation and ingestion.

In fact there is a paper available on these anomalocaridid faecal pellets. It was a University of Kansas Paleontological Contributions paper written by R. A. Robison though I am not sure of the exact reference. Hopefully the chap who sold me the fossil will be kindly obtaining a copy for me soon so we can hopefully resolve this.

Personally, I lean towards vomit.

(This thread is turning surreal! :smile: With these various interpretations, do you think we should have a poll? We could call it Phil's Faecal Pellet Poll).
Don't make it a poll unless you make it possible for me to change my mind a couple of times!

I guess it could have been a ball turd that got crushed under the weight of the overlying sediments (have I mentioned how closely small Goniatites resemble deer pellets, I have picked up quite a few thinking I had a good find!).

While digging trilobites in the wheeler shale, you can find layers packed with small trilobite parts, but they are not usually in a specific shape, more random clusters and irregular shapes. Maybe half washed dung or upper water column hurl?
Hi Phil
I was browsing the net to find anything on trilobite predation and this forum came up. I am interested in seeing the trilobite in question. Would it be possible to email the picture(s) to me?

paleosearch;79543 said:
Hi Phil
I was browsing the net to find anything on trilobite predation and this forum came up. I am interested in seeing the trilobite in question. Would it be possible to email the picture(s) to me?


Hi Albert,

Goodness me, this thread is almost three years old - amazed to see it rise up from the dead like Lazarus like this! What was I going on about back then?

By some miracle, after an hour of hunting I actually found a file with some of the pictures from this thread on it. Here's three of them, but they are really poor quality I'm afraid. Back then I had no digital camera so had to place anything I wanted to show here on the scanner and hope for the best. I've still got the fossils and have graduated through three cameras since then so I'll try and retake these pictures sometime soon for you. Until then, here's some of the old ones for you, with my apologies.

cuttlegirl said:
I am curious as to whether you ever determined if it was regurgitalite or fecal matter...

No, I did not get to the bottom of that I'm afraid, no pun intended. It's difficult to know who to consult about anomalocarid faeces.


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Great thread! Very informative. Many is the time I've picked up what looks like a perfect little goniatite from a moorland stream only to find it to be unpleasantly squishy!

I'd also go with the regurgitate option I think. Good to know there's a technical term for it so I can re label some of the collection - vomit just doesn't have the right ring to it. In the carboniferous site I've been to large flat nodules were not infrequently found to have variably sized amorphous orange blobs in them and less frequently they were packed with identifiable remains - broken up arthropods and fish bones and scales. I've always thought that this is what they represented, indigestible remains of somethings lunch so its interesting to see similar things from other eras. The larger one shown here has been found to contains fish scales and bone, probably scorpion remains including an arm and claw and a fairly intact spiny millipede. The smaller one shows fish remains.

Ooops.....forgot to attach the pics. I'm always doing that at work aswell. Here they are. Apologies if they are none too clear - the details are pretty small.



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Wow, those are amazing fossils there Andy. They remind me a little of the Mazon Creek nodules, but larger. What sort of environment are they thought to have originated from? I'm guessing it must have been a shallow lagoon allowing a mix of terrestrial arthropods and fish. I really don't know how you managed to identify those fragments you have indicated, most impressive.
Hi Phil

Yes, they are very similar to the mazon nodules although slightly older. They have a similar fauna to the Braidwood assemblage from mazon, crabs, spiders, scorps, millipedes etc and a wide variety of plants but none of the true soft body preservation which mazon nodules are famous for. The environment is likely to be a clastic swamp - the nodules come from the mudstones overlying one particular coal seam and there are also upright tree stumps and rooting systems exposed in situ so you're probably not far out with the lagoon idea - heavy rain or river bank breaks would wash material in to low lying areas where the conditions were right for nodule formation. Not sure as to which critter was producing these - shark egg cases are not uncommon finds there as are big fish scales but there's little other evidence of vertebrate predators. As regards identifying the bits, the pics don't really so them justice. A magnifying glass helps aswell!

Notice that the first one debris almost forming a ring like your trilobite specimen. Perhaps its a feature of the way the regurgitate sometimes hits the bottom - maybe it 'splashes' on impact, being denser than the surrounding water and the heavier components quickly settle out while the lighter particles disperse? Think of those films of drops of milk hitting a surface and forming that crown effect.

Apologies to everyone for drifting off cephalopods.


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