"Professor Rex" is one of the Toy Story Treats that aired on ABC's Saturday morning line-up in 1996.
Plot[]
Rex is worried over a debate on whether dinosaurs were hot-blooded or cold-blooded, while some of the toys that are listening to him (including Woody) eventually get bored and leave. At the end, one of the Aliens is the only one who is still interested in it.
Video[]
Paleontological Debate
The Short