Scooby-Doo the series and the billing, in an attempt to boost "Scooby-Doo"s slipping ratings. The 1979–80 episodes, aired under the new title "Scooby-Doo and Scrappy-Doo" as an independent half-hour show, succeeded in regenerating interest in the show. Lennie Weinrib voiced Scrappy in the 1979–80 episodes, with Don Messick assuming the role thereafter. Marla Frumkin replaced Pat Stevens as the voice of Velma mid-season. As a result of "Scooby-Doo and Scrappy-Doo's" success, the entire show was overhauled in 1980 to focus more upon Scrappy-Doo. At this time, Scooby-Doo started to walk and run anthropomorphically on two feet more often, rather than on
Scooby-Doo the predominantly skeptic oriented formula to that of most television dealing with paranormal themes, and considered that an adult analogue to "Scooby-Doo" would be a great public service. "Scooby-Doo" has maintained a significant fan base, which has grown steadily since the 1990s due to the show's popularity among both young children and nostalgic adults who grew up with the series. Several television critics have stated that the show's mix of the comedy-adventure and horror genres was the reason for its widespread success. As Fred Silverman and the Hanna-Barbera staff had planned when they first began producing the series, "Scooby-Doo"s ghosts,