ALIVE WITH THRILLS THAT STARTED A MILLION YEARS AGO!
On a Caribbean island, a construction crew using dynamite accidentally disrupt a frozen area underneath the water. Located in the explosion rubble are two perfectly-preserved dinosaurs, as well as a Neanderthal man. The prehistoric beings come to life and are unleashed on the unsuspecting population.
The rifftrax version is great to break up the slower parts with jokes, but this is definitely up there when I think of mid 20th century b movie sci-fi along with Them! And The Blob