WATCH: Wallace Shawn's Dino Gets His Own 'Toy Story' Short in 'Partysaurus Rex'

Attached to prints of Disney-Pixar's Finding Nemo 3-D re-release next month will be a new Toy Story Toon spin-off short starring the voice of Wallace Shawn as the adorably naive dino Rex, who goes from Debbie Downer to the titular Partysaurus Rex at bathtime. Cute enough, no? Watch a clip after the jump and tell us if the law of diminishing returns applies to stories built around second- and third-tier Toy Story characters.

More on Partysaurus Rex:

Poor Rex. Buzz, Woody and the rest of the "Toy Story" gang think he is a just a wet blanket. But when Bonnie takes him to bath time, he goes from a party pooper to king of the hot tub! Creating a bubble bash like no other, everyone's raving about the Partysaurus Rex!

Directed by Pixar veteran animator Mark Walsh and produced by Kim Adams, Disney•Pixar's new short "Partysaurus Rex" makes a splash in theaters in front of "Finding Nemo" on September 14, 2012.