Is it possibly Adventures in Dinosaur CityAdventures in Dinosaur City?
From Wikipedia:
Adventures in Dinosaur City (known as Dinosaurs The Movie in Europe) is a 1991 television film directed by Brett Thompson. The film stars Omri Katz, Tiffanie Poston, Shawn Hoffman, Rob Sherwood, Patrick Labyorteaux, and David Jolliffe.
The story involves a trio of teenagers, named Timmy (Omri Katz), Jamie (Tiffanie Poston), and Mick (Shawn Hoffman), who enjoy watching their favorite TV show which features anthropomorphic dinosaurs. Wanting to watch it on a better screen, Timmy, the youngest of the three, suggests that they try watching it on his father's screen in his laboratory. The moment they turn it on, a vortex sucks the three into the TV screen, and into their favorite show.
Upon entering the new world, the trio comes across a flightless Dimorphodon named Forry (Rob Sherwood). Reluctant, his knowledge of Dinosaur City proves useful as he guides the three to Tar Town where they join up with a Tyrannosaurus named Rex (Patrick Labyorteaux) and a Triceratops named Tops (David Jolliffe), two dinosaur freedom fighters willing to ignite a revolution against the villain, Mr. Big (Patrick Labyorteaux) and his caveman henchmen "The Rockies".
