Carboniferous Nacre

[piranha]

from Schram 1984:

 

The arthropod fauna of these beds (Table 1) is composed of tyrannophontid stomatopods, portions of aeschronectid hoplocaridans, eumalacostracan forms, concavicarid crustaceans, and a mycteropid eurypterid.  The diverse combination of phyllocarids, rapacious stomatopods, aeschronectid, and eumalacostracan forms is similar, but not identical, to a Carboniferous community type designated by Schram (1981) as near-shore marine.

 

In summary, although this paper deals with crustaceans from a number of localities and horizons, their restricted geographic extent makes generalization difficult.  However, it seems reasonable to conclude that these crustacean assemblages are apparently of a marine type, probably from deeper water than the communities of the Upper Carboniferous recognized to date, that they lived in some proximity to anoxic conditions, and that they were subject to catastrophic kills.

 

 

These fossils are preserved as a combination of organic residues on the shale and impressions in the rock.  Pyrite replacement has also taken place and is especially evident in the preservation of some of the thinner, more delicate structures such as membranous uropods and thin carapaces.

 

Peachocaris acanthouraea:

Remarks. -The specimen is a rather diaphanous preservation of a thin organic residue with pyrite replacement.  It is quite reflective, and best studied with high-angle lighting, though consequently it is difficult to photograph (Figure 6).

[Missourian]

BTW, has anyone else had that deja vu moment when you seem to have some vague, nagging recollection that makes you go "my goodness, I think I may have something like that in my collection." I have a couple fossils stored away that are tantalizing me now, but I doubt they will turn out to be eurypterids (even though they are from one or more of the same shale beds mentioned in the article abstract above). Haven't had a chance to pull out the collection yet....

[Missourian]

Plus, it is surprising that Mycterops, which I've heard is a fresh or brackish water animal, is present in black shales that are (interpreted to be) deep water deposits containing pelagic organisms.

[piranha]

more from Schram 1984:

 

The marine crustacean faunas of the Nebraska-Iowa black shales do not appear to fit into a Zangerl-Richardson model because the predominance of tyrannophontid stomatopods is characteristically linked with distinctively marine habitats (Schram, 1981).  Conversely, the predominance of active, rapacious, bottom-dwelling types as the tyrannophontids represented in these assemblages is not completely compatible with the interpretation of stagnant, poisonous deepwater habitats envisioned in the Heckel-Baesemann model.  However, it could be compatible if the stomatopod fauna inhabited the bottom along the fluctuating edge of the anoxic bottom water layer, and perhaps possessed some additional tolerance for low oxygen conditions.  These fossils thus may represent a catastrophic kill.

[Tidgy's Dad]

Tremendous fossil, that's absolutely beautiful! 

[Bullsnake]

On ‎7‎/‎4‎/‎2018 at 12:38 AM, Missourian said:

BTW, has anyone else had that deja vu moment when you seem to have some vague, nagging recollection that makes you go "my goodness, I think I may have something like that in my collection." I have a couple fossils stored away that are tantalizing me now, but I doubt they will turn out to be eurypterids (even though they are from one or more of the same shale beds mentioned in the article abstract above). Haven't had a chance to pull out the collection yet....

[Missourian]

On 7/4/2018 at 12:38 AM, Missourian said:

BTW, has anyone else had that deja vu moment when you seem to have some vague, nagging recollection that makes you go "my goodness, I think I may have something like that in my collection." I have a couple fossils stored away that are tantalizing me now, but I doubt they will turn out to be eurypterids (even though they are from one or more of the same shale beds mentioned in the article abstract above). Haven't had a chance to pull out the collection yet....

 

It took me long enough, but I finally dug it out of my collection. It's not a eurypterid, but rather a.... not sure:

 

 

 

Cephalopod, perhaps.