Southern Colombia (south-western Putumayo), north-eastern Ecuador (western Napo), central and eastern Peru (Junín and Ucayali south to Madre de Dios, Cuzco and Puno), northern Bolivia and western and west-central Brazil (Acre, Rondônia, Pará, Mato Grosso).
 
Population
Estimated population is unknown (2010).
Dusky-tailed Flatbill (Ramphotrigon fuscicauda) [XC229017]
by John V. Moore from Pantiacolla Lodge, Madre de Dios, Peru (song)
Dusky-tailed Flatbill (Ramphotrigon fuscicauda) [XC753536]
by Iv\u00e1n Lau from Laguna El Correo, Colombia (song)
Subspecies
Present genus formerly believed to be allied to flatbills (Tolmomyias and Rhynchocyclus), but apparently belongs instead with Myiarchus and relatives, based on cranial, syringeal and nesting characters. Molecular data is still lacking. Formerly placed in genus Rhynchocyclus.