After visiting the American Museum of Natural History, four boys rent a rowboat in Central Park only to pass through a mysterious tunnel that takes them to the 'river of time', on which they paddle further and further into Earth's prehistory. This is an Americanised version of the Czech sci-fi/fantasy film 'Cesta do praveku' (which starts and ends differently) and is likely best remembered for some good model work and effective 2D and 3D animation of assorted antediluvian beasts, including a mammoth, a deinotherium, and a phorusrhacos (one of the South American 'terrorbirds') from the cenozoic; a sauropod, a stegosaurus, a hadrosaur and a ceratosaurus from the mesozoic; and a primitive amphibian and a meguneura (giant 'dragon-fly') from the paleozoic. The film was intended to be educational so there is no real plot and one of the boys, nicknamed 'Doc', carefully explains what the other three are marvelling at, so the dialogue is a bit stilted and artificial sounding (likely not helped by the English dubbing in the version I watched). The animated animals are very well done (considering the age of the film) and, as a typical dinosaur-obsessed boy in the early 1960s, I would have been 'glued to the screen' watching 'real' dinosaurs (as opposed to lizards and baby alligators with fins glued to their backs). Worth watching if only for the ambitious attempts at depicting a variety of primaeval Earths. Looking for a subtitled version of the Czech film might be worth the effort but the dubbed version available on YouTube (as of this writing) is watchable. Some of the special effects (notably the fight between the stegosaur and the ceratosaur) resurfaced in 1961's 'Pathfinders to Venus', a British 'educational' science-based adventure show for kids.
