Pennsylvanian black shale unknown

[connorp]

I found this while splitting some Middle Pennsylvanian black shale (Carbondale Fm) today in Illinois. It certainly looks fishy, but I haven't seen anything like it before. Any ideas?

[jdp]

Well, there's a whole mess of conodont elements inside, but I wonder if this might be a phyllocarid.

[DPS Ammonite]

At first I thought that it might be a Lepidodendron branch but yours is too irregular. The scales in yours do not line up diagonally in a spiral up a “stem/trunk“ like it does in Lepidodendron. I think that you might have a fish with scales. Maybe conodonts (eel like creatures) were eating a fish when everything was rapidly buried.

 

Drawings from website below.
 

https://woostergeologists.scotblogs.wooster.edu/2012/01/08/wooster’s-fossils-of-the-week-a-scale-tree-late-carboniferous-of-ohio/

Edited July 27, 2020 by DPS Ammonite

[connorp]

2 hours ago, jdp said:

Well, there's a whole mess of conodont elements inside, but I wonder if this might be a phyllocarid.

Interesting thought. The only "phyllocarid" that has been described from this unit (as far as I know) is Concavicaris sinuata. The scale ornamentation is vaguely similar to my specimen but I don't think a very good match. See Fig. 6F below.

 

 

Krzysztof Broda, Štěpán Rak & Thomas A. Hegna (2020) Do the clothesmake the thylacocephalan? A detailed study of Concavicarididae and Protozoeidae (?Crustacea,Thylacocephala) carapace micro-ornamentation, Journal of Systematic Palaeontology, 18:11,911-930.

 

2 hours ago, DPS Ammonite said:

At first I thought that it might be a Lepidodendron branch but yours is too irregular. The scales in yours do not line up diagonally in a spiral up a “stem/trunk“ like it does in Lepidodendron. I think that you might have a fish with scales. Maybe conodonts (eel like creatures) were eating a fish when everything was rapidly buried.

Thanks for your input. I don't think this is plant material either, as all plant material I've found in these shales has been at least partially carbonized, which this specimen is not.

[RCFossils]

Yo

34 minutes ago, connorp said:

Interesting thought. The only "phyllocarid" that has been described from this unit (as far as I know) is Concavicaris sinuala. The scale ornamentation is vaguely similar to my specimen but I don't think a very good match. See Fig. 6F below.

 

 

Krzysztof Broda, Štěpán Rak & Thomas A. Hegna (2020) Do the clothesmake the thylacocephalan? A detailed study of Concavicarididae and Protozoeidae (?Crustacea,Thylacocephala) carapace micro-ornamentation, Journal of Systematic Palaeontology, 18:11,911-930.

 

Thanks for your input. I don't think this is plant material either, as all plant material I've found in these shales has been at least partially carbonized, which this specimen is not.

You are correct.

Your specimen is a portion of the carapace of the Thylacocephala Concavicaris sinuata.

They are fairly abundant in certain sections of Illinois black shale.