Robert Downey Jr. to play talking dog

Robert Downey Jr. has signed to star as Mr. Peabody in a new animated feature.

The 'Sherlock Holmes' star will take on the role of the genius dog - who along with his pet boy Sherman, appears in the 'Rocky and Bullwinkle Show' - in the big screen tale of his adventures as he travels through time using his WABAC time machine, learning about history's greatest figures.

Director Rob Minkoff said the movie will also focus on Mr. Peabody's origins, explaining: "Mr. Peabody is this genetic anomaly. He does have brothers and sisters, all of them non-speaking, no super-smart dogs. He's an outcast, but has overcome it by being so great at so many things."

The role of Sherman has not yet been cast while 'The Simpsons' veterans Jeffrey Ventimilia and Joshua Sternin are writing the script

Robert will soon begin recording his voiceover work for the as yet untitled 3-D animation movie with an expected release date of 2014.

Meanwhile Robert has revealed he is excited about the upcoming 'Avengers' movie - which will also feature Chris Hemsworth from 'Thor', Mark Ruffalo as the 'Incredible Hulk', 'Captain America's Chris Evans and Scarlett Johansson who appeared in 'Iron Man 2' - and said he thinks it is going to be "extraordinary".

When asked about the Marvel Studios project, he said: "I think we're going to do something extraordinary. If we work really hard, I think we'll have something worth it."