Lesser Masticore does not have a -1/-1 counter on it.
Steps
Activate Carrion Feeder by sacrificing Lesser Masticore.
When Lesser Masticore dies, its persist ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it due to Curator Beastie.
Resolve the Carrion Feeder ability, putting a +1/+1 counter on it.