Fantasy built on a fantasy--in Bear's alternative 1947, Sir Arthur Conan Doyle's The Lost World wasn't fiction, but fact!--mingling real and imaginary characters with a quite unbelievable hodgepodge of defiantly unextinct beasties from the Carboniferous on up. Circus Lothar, the last dinosaur circus, is closing down, and its animal trainer, Vince Shellabarger, is determined to return his charges to their home, the isolated Venezuelan plateau of El Grande discovered by Professor Challenger in 1912. National Geographic's Anthony Belzoni will cover the event, assisted by his 15-year-old son Peter. Filming the cavalcade will be Willis ""OBie"" O'Brien (of King Kong fame) and special effects/animation genius Ray Harryhausen. The tough journey is made more difficult by the Venezuelan Army's quarrel with both the politicos and the local Indians. Still, the expedition reaches the rickety bridge leading on to El Grande, and most of the animals cross safely. But Dagger, a vicious predator, escapes from his cage; predictably, the bridge falls, marooning Peter, Anthony, Obie, Ray, and Billie, an Indian pursuing a spirit quest. After various adventures--the group is menaced by critters ranging from giant salamanders and hungry therapsids to huge ""death eagles""--they make it back, minus assorted limbs and teeth, bearing a couple of precious eggs. Amiable, sometimes stirring incident-packed baloney: a yarn that screams I wanna be a movie!