a giant lizard
The heaviest dinosaur known from fairly complete and reliable remains is Argentinosaurus, at around 80 tons or so. There is some (poor) evidence that still larger sauropods existed, Bruhathkayosaurus may have been some 140 tons or more (some claim over 200 tons, which would mean that it rivaled blue whales with respect to sheer weight), and Amphicoelias may have been over 60 meters in length, but it was a slender animal by sauropod standards, weighing "only" 120 tons. However, Amphicoelias is only known from sketches (the original fossil material was lost) and Bruhathkayosaurus still hasn't been properly described, so at the present time and until better remains are found (if ever), these claims remain questionable.
It is conceivable. this was more or less pressed into service in the thirties by Hollywood to use midgets or small-statured actors and actresses ( Mickey Rooney and Judy Garland , for example) to play juvenile parts- avoiding any problems with Child-labor laws, or potential Child abuse. midget actors were a tractable susbstitute. I believe they were used on Little Rascals/Our Gang as they seemed to act too mature for kids, another example of midgets as thespians was ( the Munchkins) in Wizard of Oz. more recently a midget actress did some of the moving shots for E.T. which were beyond the range of the robot, so to speak. small wonders.