Having read your interesting and thought-provocative post this morning, about gastroliths, fermentation bags, and Hoatzin, I wonder if Hoatzin's pouch could be the source of that bird's often-reported, offensive-to-humans, odor. Can you (or anyone else) enlighten me on the apparent source of that odor? (Am I off the dino subject? Not if birds are dinos. -- Oops! Don't want to start a controversy here! :-)
Incidentally, I read somewhere (great reference, huh?!) that crocs (or was it alligators, or both?) carry gastroliths 'for ballast'. Not being Paul Willis or a croc expert at all, I wonder: (1), Do crocs really have gastroliths?, and; (2), Is or isn't the ballast interpretation a valid one? [Presuming the answer to question (1) is yes.]
I like your adage, "All questions are valid; all answers are tentative", but would still appreciate even tentatively-informed comment on questions.
Thanks, Ray Stanford