@GeschWhat, Do you think this is a coprolite or gut contents? This is from a very soft shale and was said to have been collected from the "Kamp Ranch Formation" near Dallas, TX (although I think it must have been another member of the Eagle Ford Group based on the composition and nature of the matrix) (If anyone is familiar with these Prionocyclus-rich shales and has suggestions on which member they likely came from, please chime in).
In this image, I have pointed out 2 of the fish bones (there may be more). You can also see bivalves. The fossils in this layer are isolated, so it's not like a "hash plate". Most of the fossils are Prionocyclus hyatti (?). But I found this discrete concentration of bits, and I wonder if it is a coprolite or gut contents. Maybe from an ammonite... Scale in this photo is mm.
Here is a picture of a piece of the shale showing the abundant ammonites. (scale in cm/mm)
Thanks for any assistance!