I've got good news at least for the three (so far) commenters here, and perhaps for others as well: THE ANIMAL WORLD has survived intact, and is available from the Warner Archive.
I bought it, not surprisingly, for the dinosaur sequence; I too got those ViewMaster reels in 1956 and have wondered ever since what the movie was like. The movie as a whole is a pretty-good nature documentary, akin to (though not quite as good as) the Walt Disney True-Life Adventures of the 1940s and '50s. The O'Brien-Harryhausen animation scenes are justifiably the main draw here, and they alone are worth the price of the DVD.