In Africa, paleontology understudy Susan (Sean Young) and her husband George (William Katt) discover that the local legend of the Mokèlé-mbèmbé is in fact a family of living brontosauruses - a father, mother and a hatchling. In doing so, George and Susan accidentally lead Susan's mentor, mercenary scientist Eric (Patrick McGoohan) and his hired team of soldiers, who kill the father brontosaurus and capture the mother, leaving George and Susan the sole caregivers of the infant, whom they nickname "Baby". They fight to protect Baby from the dinosaur hunters and rescue Baby's mother.
A 1985 live-action Disney film released under its Touchstone label, unlike other dinosaur films of the time that relied on Stop Motion for its visual effects, Baby: Secret of the Lost Legend, opted instead for a combination of life-sized animatronics and puppets worn by people to provide the walking motions; the film was Darker and Edgier than most of Disney's fare at the time, but still insisted on moments of cuteness involving Baby. As a result, the film mostly failed to find an audience and is typically dismissed by critics. However, it is fondly remembered by most of the people who saw it as children in the 1980s.
Compare to The Last Dinosaur, another earlier dinosaur film that used similar effects.
Secret of the Lost Tropes:
- Artistic License Paleontology: The Brontosaurs are designed with blunt macronarian style heads, despite the fact that they had more tapered diplodocine heads being common knowledge, or at least easy enough to find out if the research was done, by the time the film was produced.
- Big Damn Heroes: The natives. Twice.
- Coitus Interruptus: Try as they might, George and Susan absolutely cannot get around to making a baby of their own without at least one of the sauropods crashing it. The first time they try, one of the adult dinosaurs mistakes their tent for something edible. The second time, they have Baby literally coming between them. Subverted when they finally get Baby to leave them alone long enough to make love, only for him to wander off, which ultimately leads to him getting captured.
- Disproportionate Retribution: Nigel really didn't deserve to get killed. At least it looked funny seeing him electrocuted.
- Dramatically Missing the Point: After the soldiers gun down the father brontosaur:Eric: Do you have any idea what you've done?! It was one of a kind!Colonel Nsogbu: No, professor. It was two of a kind. (points at the tranquilized mother bronto) That is one of a kind.
- Even Evil Has Standards: For all his villainy, Eric has some moments:
- He is disgusted with the soldiers who shoot and kill the father bronto.
- He murders Colonel Nsogbu for constantly overdosing Baby's mother on tranquilizers. It's then quickly subverted when he frames George and Susan for the murder.
- Evil Mentor: Eric, the main antagonist, is Susan's former mentor.
- Family-Unfriendly Death: Notably Eric, who is snatched into the jaws of the mother Bronto and shaken around, which shows blood and had to be edited out on some television airings. Doubles as a Shout-Out to King Kong (1933).
- There is also his assistant Nigel getting violently electrocuted onscreen. This too, was edited out in some airings.
- Family-Unfriendly Violence: See above. Seeing the male Bronto getting gunned down isn't very pretty either.
- Intrepid Reporter: Inverted with George, and then played straight. Initially he's interested only in African baseball stories and not wanting to go searching for dinosaurs, once they actually find them he is as starry-eyed as his wife.
- Jerk with a Heart of Gold: George.
- Living Dinosaurs: The last three sauropods.
- Mama Bear: The mother bronto, of course. Eric learns this the hard way by the end.
- Mook Lieutenant: Sergeant Gambwe to Colonel Nsogbu. Then to Eric after Nsogbu pushes Eric's buttons one time too many.
- More Dakka: How the father brontosaurus dies.
- My God, What Have I Done?: Eric has one of these moments after Baby is seemingly killed. Not that it saves him from Mom's wrath of course.
- National Geographic Nudity: Used in several shots with women of the natives and during the carnival in the opening.
- No Escape but Down: When being chased in a cave by Eric and the soldiers, Susan, George and Baby get themselves cornered in the edge of an underground waterfall, they decide jump off.
- People in Rubber Suits: For Baby's special effects they used a rubber-covered harness which would be worn by a person, allowing them to walk on fours. The eyes, mouth, neck and tail's movement would be remote controlled by the crew.
- Roaring Rampage of Revenge: When the mother brontosaurus is freed at the end of the movie, she rampages something fierce.
- Stock Dinosaurs: Brontosaurus.