Just to tie up loose ends. I have tracked down and had a conversation with the student author of the Ball State paper on YP feeding. Recall the faculty author was less than helpful. She states that all the YP they measured were dead. The mouth gape was measured with digital calipers. They did a max stretch gape both horiz and vert. They inserted the "jaws" of the caliper in the proper orientation and opened them until they wouldn't go any further. She admitted this is not a realistic feeding opening, but was selected as most repeatable among different folks measuring.
We already had concerns about the YP dataset as it showed YP having a larger gape than LMB, but this explains why. As the measurement doesn't really fit our stated gape model, I'll leave that YP data out. Our experts may want to weigh in, but when a horizontal gape is measured, I can see slightly opening the mouth to get inside, but stretching a fish to some unnatural limit seems not fitting.
