Do you think that we'd have enough time to reference our notes for each question? Or would it take longer to get the facts straight in our head for each question? If we were to memorize it, would it be better for each of us to memorize all animals, or each memorize half?
In the texas rules, it states that the test will be 50 questions long and multiple choice. You should check your state's rules.
As for the ID, at our last tournament, my partner and I both memorized how to identify all animals since they're all pretty easy to ID. The test was in stations with 3 minutes per station and 2-4 questions at each station. Three minutes was actually plenty of time---we were pretty much sitting around waiting for the time to be up most of the time.
Now about referencing notes for each question, it really depends on the length of the test, as well as how you organize your notecards/binder. A typical proctor, especially at an invitational, will probably not put in the time to write more than about 50 questions. Also, I would personally find it difficult to memorize the dates of introduction and scientific names, but I suppose you could be familiar with the ecological impact, etc.
Hope this helps :D