The Land Unknown (1957)

Starring Jock Mahoney, Shawn Smith, William Reynolds, Henry Brandon, Douglas Kennedy
Directed by Virgil Vogel
(actor & director credits courtesy IMDB.com)

A naval research expedition to the South Pole brings along a magazine reporter, but they're forced to crash land on a strange tropical plateau where they encounter prehistoric creatures.

An underrated dinosaur film from Universal-International, the picture boasts a number of interesting special effects, and the creature mockups of a Tyrannosaurus Rex and plesiosaur offer excellent and fearsome detail although no animation is used.  Regardless, the dinosaurs look great in close-up, and the monster suits/puppetry used are very effective, framed against a number of artistic and convincing backgrounds.  Even footage of real-life lizards blown up to giant size, although cruelly staged and largely unnecessary, comes off fairly well visually.  There's some dated situations involving Shawn Smith's heroine, but she still comes across as a strong-willed character, and the rest of the acting ensemble deliver believable performances.  Henry Brandon is particularly memorable as the cruel Dr. Hunter, stranded on the plateau for 10 years or more, who considers himself the area's human master, and schemes to take whatever he wants.  A nice mix of sci-fi action and human drama make this a picture very worth seeking out, and the film's strong visual impact adds to the fun.