Iwao Takamoto, the US animator who created cartoon dogs Scooby-Doo and Muttley, has died aged 81.He was responsible for characters from The Flintstones and The Jetsons when he worked for the Hanna-Barbera studio.And he assisted in the design of films including Peter Pan, 101 Dalmatians and Cinderella, during a career spanning more than six decades.