Lost Continent is a 1951 science fiction film. It stars Cesar Romero, Hugh Beaument, Sid Melton, John Hoyt (who has a Star Trek connection), and Whit Bissell (who also has a history with Star Trek). TCM has an overview.
There's a break in this video at 55 minutes, then it skips to the last 3 minutes of the film. It is a total of 58:22 minutes long out of an 83-minute long film. During the 25 or so missing minutes there's one death and a cataclysmic occurrence that causes earthquake and explosion, and if there are prehistoric beasts in this film they are in the missing segment.
Here's 10 minutes of video (3 segments) from the missing 25: