Pennsylvanian unknown microfossil

[connorp 1,160]

I found this small specimen while splitting some Pennsylvanian black shale today. As usual, I'm not sure what it is. Looks like a jaw to me but I really don't know. It measures about 5mm long. Any thoughts? @jdp @RCFossils @deutscheben

[Petalodus12 207]

I agree that it looks somewhat like a jaw. Don’t know from what, though. Hopefully you get an ID

[deutscheben 1,053]

Fascinating- I haven’t seen anything like it, though- with those structures in the middle it’s quite interesting. 

[jdp 599]

Could be a set of jaws, but I'm not 100% convinced and I'm open to other interpretations.

[Darbi 212]

Wow...that's really a difficult puzzle. I looked through the google images about the fossils of Illinois Pennsylvanian rocks and I didn't come across any that resemble this microfossil. A couple closest things that came to my mind is a crinoid crown with several missing arms and these 'teeth' are pinnules, or a strange-looking graptolite. I have some doubt whether if it's a jaw from some animal.

[jdp 599]

Maybe a claw from some sort of malacostracan?