Unknown "pellets" from Pennsylvanian of the Piesberg (Germany)

[paleoflor]

L.S.,

 

Hope someone might have an idea what these could be. This specimen comes from the Carboniferous (Westphalian D, Pennsylvanian) of the Piesberg quarry near Osnabrück, Germany. These little "pellets" are about 2-3 mm in length and preserved in illite (typical for the locality). I added one microscope image, but unfortunately they show little structure. Curious and looking forward to hear your thoughts!

 

Kind regards,

 

Tim

[TqB]

Possibly mud clasts? Or are they carbonaceous? Charcoal fragments?

Edited November 19, 2021 by TqB

[paleoflor]

22 minutes ago, TqB said:

Possibly mud clasts? Or are they carbonaceous? Charcoal fragments?

Sorry, probably my description as "pellets" was a bit vague. They're actually nearly two-dimensional structures, not clasts or fragments. The silvery-gray color is caused by a film of illite (sometimes referred to as gümbelite in older literature describing the locality). This form of preservation is typical for the Piesberg quarry. Plant remains and animal fossils alike (e.g. Euproops) are preserved this way.

[pachy-pleuro-whatnot-odon]

Plant after broken up into tiny fragments? Possibly as the result of insect agency? 

Edited November 19, 2021 by pachy-pleuro-whatnot-odon

[abyssunder]

I think, there might be phenocrysts in your specimen, but I could be wrong.

porphyry

 

 

Edited November 19, 2021 by abyssunder

[westcoast]

Look like fragments of plant to me, particularly if you look at the larger piece near the top of the first photo which appears to be disintegrating..

[pachy-pleuro-whatnot-odon]

6 minutes ago, westcoast said:

Look like fragments of plant to me, particularly if you look at the larger piece near the top of the first photo which appears to be disintegrating..

 

I agree, this would seem more likely than the presence of, what I understand, would otherwise be pyroclastic elements - especially in absence of other traces of volcanism...

[paleoflor]

Thanks for the feedback all!

 

I'm quite certain they're not phenocrysts, as this doesn't fit with the depositional environment, nor with the two-dimensional character.

 

Of course plant debris is an option. I do wonder, though, what kind of mechanism would produce such regular fragments? I have seen my fair share of plant fossils from the Piesberg, in various stages of disintegration and decay, but never before were the fragments this regular shaped (all rounded rectangles of comparable size). Insect agency is an interesting thought here, though I wouldn't know how to test that hypothesis...

 

Would bromalites be an option at all?

[pachy-pleuro-whatnot-odon]

3 hours ago, paleoflor said:

Insect agency is an interesting thought here, though I wouldn't know how to test that hypothesis...

 

I know, that's kind of the problem with this hypothesis... Still, I guess you'd go about it much the same way that palaeontologists do for other living organisms and archaeologists for cultural practices: you look for a living (or, at least, history recorded) analogy. As such, an opening move would be to mention leafcutter ants, which collected leafs have a certain uniformity to them (source):

 

 

As to bromalites: not that I've got any experience or knowledge to base this on, but I wouldn't expect so. Thing is, if you reason about it, this doesn't result in a realistic-sounding hypothesis. As a mind exercise, lets split the concept of "bromolite" into its known practical constituents:

• Coprolites - as I understand, one of the difficult things about determining the diet of herbivores from coprolites, or even identifying these as such, is that much of the plant material is turned into a heterogeneous paste when it passes through the intestinal tract. As such, you wouldn't expect any recognizable plant material to show up in coprolites, let alone spread out over a broad surface. There is, of course, the possibility that each of the pellets itself is a coprolite of a small animal or insect, the floral component of their excrement having caused their coprolites to fossilise with the same preservation as the plants themselves. But this, to me, sounds less likely when you consider the spread and distribution of these pallets and the proximity to more fully preserved plant matter in which they are found.
• Cololites - for the same reasons as above sounds unlikely to me, and even more so since you'd expect cololites to have the shape of the colon of the animal that produced it.
• Gastrolites - possible, as far as I'm concerned, and stomach acid may have led to the rounding of all these bits of plant matter. It's just difficult to substantiate without having a body fossil to associate the material with.
• Regurgitalites - I wouldn't know of any herbivore that externally regugitates (although many of them do, of course, internally), with this practice being much more common amongst predators that need to get rid of the hard parts of their prey they may have swallowed, a need herbivores don't really face and have found other solutions to when reprocessing of their food is required (ruminating, eating faeces)

While there's undoubtedly a lot of criticise on my above reasoning, I think these illustrate the kind of approaches you might need to take to figure out what's going on with these "pellets".