I am an educated person from the area and era of your specialization and I come across a fossil what do I think it is (if anything) and what story (if any) do I believe about how it got there?

We don't allow "what if" questions, nor "in your field" (a.k.a. "throughout history") questions since they tend to attract trivia and answers without any evidentiary basis. If you'd care to specify a time and place, and remove the bit about the speculative scenario, that'd be fine. Alternatively, /r/HistoricalWhatIf would give a good welcome to the "what if so-and-so discovered a T. Rex" part of the question.