I found this in aurora fossil mine, late 70's.
I was a young kid at the time and found this in many, many pieces. I remember digging all around finding what I could. I'm sure I wasn't as thorough as I needed to be, but oh well.....
Over the years I have never been able to properly Id this.
It looks like a long beaked whale or porpoise jaw.
The closest thing I can find online is a Ninoziphius Platyrostris.
As always your helps is greatly appreciated.....