>> Is your Apatosaurus resource playable in Civ IV Beyond the Sword or will it have to be played in Civ III?
The Apatosaurus Ress. and Unit are for Civ-III. Civ-IV uses a radically different engine and doesn't support 2D sprites.
>> Does it load and play automatically or does it need to be loaded in a mod downloaded of this web site? If so which mod or scenario will it be found in?
They need to be implemented in a mod. There is at least one mod that'll use them and that'll be released to the public : The Lost World from the Steampunk team. You can follow the progress in the Projects CivIII subforum
Thanks for the comment ! You might find that I'll answer quickly if you post in the main thread rather in my personnal page comments.