Pennsylvanian bone?

[connorp]

I took advantage of the (eerily) nice weather today to make a trip to my favorite spot, an exposure of the Pennsylvanian LaSalle Limestone near Oglesby, Illinois. I found what appears to be a fragment of bone, or at least that's my best guess. The "inside" is very smooth with some twisting striations running partway down. What's left of the "outside" is porous and purpleish, similar in color and texture to the petalodont roots I find which is why I thought bone. I also found a small fragment (pictured) right next to it that appears to be associated, although I haven't found where the two might join yet. This certainly doesn't look like any shark teeth I've found, and besides the occasional fish scales or tiny indeterminate fragments, I've never found any other vertebrate material. I will say that my first thought was a tetrapod bone fragment as I know at least one such specimen has been found here, but I won't get my hopes up just yet.

 

[Rockwood]

Almost looks more like tooth (enamel?) in there ?

[Fossildude19]

I'd like to see shots of the "ends" of the item. 

 

@jdp

 

    

[jdp]

I think the very dark material is bone, and the rest is the impression of the bone on the infilling matrix. It could indeed be tetrapod, but I'd need to see a few more angles.

[westcoast]

Very nice find, tetrapod looks a reasonable option based on those pics.

[connorp]

Here are a few more shots @Fossildude19 @jdp

[jdp]

Definitely bone. Possibly tetrapod. Maybe a piece of skull but I'm honestly having a very hard time pinning it down to a specific bone.

[connorp]

38 minutes ago, jdp said:

Definitely bone. Possibly tetrapod. Maybe a piece of skull but I'm honestly having a very hard time pinning it down to a specific bone.

Thanks, that’s what I figured. Looks like there’s a lot covered by matrix, I’ll post results if it preps well.

[deutscheben]

Interesting! I will say that so far all of the bits I initially thought were bone fragments from this site turned out to be the exposed undersides of crusher teeth, so that would be my first guess for what the impession and remnants are. But I certainly would not rule out the possibility it is a part of a shark spine or other bone either- it would require a closer examination and more expertise. 

[connorp]

24 minutes ago, deutscheben said:

Interesting! I will say that so far all of the bits I initially thought were bone fragments from this site turned out to be the exposed undersides of crusher teeth, so that would be my first guess for what the impession and remnants are. But I certainly would not rule out the possibility it is a part of a shark spine or other bone either- it would require a closer examination and more expertise. 

The more porous material certainly reminded me of the petalodont roots I so frequently find. However the whole piece seems too big to be a part of any tooth to me, which is why I'm thinking bone rather than tooth fragment. If I can prep it well maybe that will help. It's proving to be difficult though, the bone flakes off almost as soon as it gets exposed. I'm going to hold off until I'm back from holiday so I can apply consolidant as I go.