Mongolia, Late Cretaceous Period (Djadochta Formation)
I made this illustration for Earth Archives - you can read more about the strange and wonderful dinosaurs of the Gobi Desert there.
The inflatable display structure on the male Citipati is highly speculative, but not outside the realm of possibility. Modern birds like frigatebirds and prairie chickens have similar structures, but evidence for them would be difficult to recover from the fossil record.
[Please don’t use or reproduce without permission, and thanks for viewing!]