4.5" Fish Fossil (Knightia?)

Description

I am uncertain, but this appears to be a type of knightia fossil fish from 50 million years ago.  I own another one from Wyoming, and the stone the fossil is in is very different.  This one is harder than the white surrounding stone Wyoming fossils, and appears to have some iron in the rock judging by the rust color.  I'm not sure where it comes from, but it could be anywhere, but it doesn't seem to match the Wyoming fossils.  It appears to have 3 ventral fins and 1 dorsal fin.  The rock is about 5.75" wide with the fish measuring about 4.5" (see photo with ruler).  I'm not a fossil expert, but I am trying to describe it as best as I can.
It has a mounting bracket glued onto the back (not screwed in).  No artificial coloring of the fish (all natural).
I am providing high resolution photos for you to judge condition yourself, but if you need additional photos or have any questions, do not assume -- please contact me before purchasing.
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