A pterodactyl among the ruins of Aan, a city that was never discovered. Completely realistic organisms in completely speculative environments is a delicious vein of palaeo art that has been rarely tapped into.
excellent, nemo-ramjet! i truly admire your speculative works and how much effort you put into making them realistic. i could really imagine myself with one of these in a prehistoric or desolate environment. you are an inspiration and a true artist.
Plenty of fantasy and camp SF incorporates this, though. Lovecraft did some amount of this a few of his stories, with a whole subterranean city built by prehistoric reptiles in "The Nameless City". But you're right: there's been very little modern artwork depicting realistic extinct fauna in speculative of fictional recreative contexts. The closest I can think of is Dinotopia but that was set up as dinosaurs in a (late 19th century?) fantasy setting.
Edgar Rice-Burroughs was rather good at that sort of thing. His world are variously populated with realistic and wholly speculative creatures, the jungles of the Tarzan books were home to big cats of various hybrid kinds, including saber-toothed, as well as valleys home to some dinosaurs (his rather fierce, omnivorous ceratopsian could be viewed as ahead of its time, aside from being the offspring of hybridization between T-rex and Triceratops.).