Tannadice skipper Jon Daly gave his side a 13th-minute breakthrough and a second on the counter-attack from Craig Conway only three minutes after the interval clinched the win before substitute Johnny Russell put the icing on the cake with a late third.
The defeat leaves Colin Calderwood's outfit with only three victories in 17 games during his sorry tenure.
Now without a goal in seven outings, the Easter Road men lie in 11th spot, precariously just two points above bottom side Hamilton.
Calderwood handed debuts to new signings Martin Scott, who joined from Ross County this week, and Liverpool youngster Victor Palsson as he made four changes in an ultimately unsuccessful bid to find a solution to his team's dire sequence without a victory.
Source: PA
Source: PA