Starfish Or Bryozoa Or Other From Mifflin Ordovician

[Stocksdale]

Here's an odd thing that I can't figure out. It is from the Mifflin Member of the Platteville Formation (Ordovician). Found in Northern Illinois.

Don't know if it the "starfish looking thing" is attached to a larger something or if the whole thing is one creature.

Edited June 28, 2013 by Neophytus Elginian

[Roz]

My first thought is a trilobite but not certain.. There are members that will know for sure..

[Al Dente]

It might be an internal mold of a rostroconch.

[Uncle Siphuncle]

Hinge line of bivalve or rostroconch.

[Stocksdale]

Just to clarify a few things. It is in a layer that has lots of cephalopods and gastropods.

And there appears to be two parts but the two things might be part of the same thing.

Here's the picture colorized to clarify the two parts.

The larger part (part 2 in picture) I thought might be a cephalopod but it has a branch-like part on the side. But, like I said, the two things might be all one thing.

[Caleb]

There is a rostroconch listed out of the Mifflin near Dixon, Illinois. Hippocardia sp, Templeton and Willman 1952. Here's a link to "The Paleontology of Rostroconch Mollusks and the Early History of the Phylum Mollusca" in PDF. It's photographed on plate 50 and looks like it may have the same hinge like pattern but the scan is a bit bad.

The Mifflin has Formation status in Illinois and is part of the Platteville Group. Once in Wisconsin it is reduced to Member status of the Platteville Formation.

[Stocksdale]

Thanks, Caleb. This was found just a bit north of Dixon, at the highway 2 roadcut.