Questions about this mystery fragment

[ajgus]

Sorry for the loooong post. I am a science and natural history illustrator, and I work part time at a fossil shop. We have various, easily identifiable specimens that come through our shop every day. But I've recently stumbled across a specimen from the depths of our collection that has puzzled me. Unfortunately, I do not know its origins so identifying it as belonging to a particular species is probably all but impossible (?). I've taken as many detailed photographs of it from every angle as I can, in hopes that a more knowledgeable mind might be able/willing to shed some light on it.

Firstly, I'd like to just confirm that it is indeed fossilized bone & not a rock. Secondly, I would love some insights as to some of the particular features. There are some exposed, whitish areas inside the specimen. I'm wondering, assuming this is a bone, if this might be fossilized marrow? When dampened with a sponge, the white areas reveal red and blue micro markings.  The largest of the exposed white areas has a distinct gash alongside it (which I've circled in red). I'm wondering if anyone thinks that this might be a tooth mark of some sort? 

There are also some distinct red markings on the exterior surfaces. I've seen examples where fossilized protein such as blood or soft tissue can manifest themselves as reddish marks. I'm not sure if that is what is being exhibited here (?).

Lastly, and as I mentioned - this is probably a longshot, is there anything discernible or recognizable about the specimen to anyone? Obviously, knowing its geographical origins & knowing more about the rock in from which it was excavated would go along way. Unfortunately, I simply don't have this information. I appreciate anything that anyone might be willing to offer. Thank you in advance!

[grandpa]

So, first things first.  A warm welcome to TFF from Austin, Tx.  You've found a great forum to address such questions.

 

Now to the specimen.  What I think I'm looking at is a chunk of petrified wood, not a bone.  The various colors are the natural process of permineralization with variation in the minerals involved.  Mistaking wood for bone is a common mistake.  In fact, I may be wrong myself.  Let's wait for others to weigh in before calling this "case closed". 

[ajgus]

Thank you for the welcome, good sir! Petrified wood did cross my mind. The more porous, "bark-like" structures appear to be more on the interior of the specimen, rather than on the outside (if that makes sense?). I wish I was better able to capture the details. I will try to upload some more hi-res shots.

[Darktooth]

I also thought wood, before I read @grandpa's reply.

[ajgus]

So here is a shot of the specimen's exterior. The cellular structure certainly looks to be that of bone, at least to my eye. 

[ajgus]

This image shows the interior. Notice how the jagged structures are on the inside, as opposed to the outside - as you would expect to see with the bark of a tree.

[ajgus]

Another shot of where the exterior has been broken away, revealing the interior. 

[ajgus]

And one more.

[jpc]

I also see petrified wood, which is easy to confuse wth bone.