I would not doubt that one bit.
There was definitely rot going on, focused primarily around the worse of the cow pie matting. I decided it would be best to trim these. I cut the entire outside edge off keeping most of the center section. It was far more manageable to move around and flesh this way as well. I had a bunch of strings for a lack of a better word, it was clearly not membrane or flesh, they looked leather leather and sinew strands. I cleared what I could but hoped these little strands wouldn't really impede the tanning process and I could just sand them off anyway.
Brains went on fine and I folded it together. Now to wait two days or so and see how it turns out.