"Martians" And Extinct Martians

Poul Anderson has half a dozen versions of Martians, then an uninhabited Mars visited in Twilight World and another uninhabited Mars colonized by Terrestrials and Lunarians in Fleet Of Stars. So, like sf in general, Anderson imagines Mars first as inhabited, then as uninhabited?

But there are intermediate positions. In James Blish's Cities In Flight and two Jack Loftus novels, Martians did exist but have become extinct. The last Martian dies as Earthmen arrive in Blish's Welcome To Mars. The hero of Michael Moorcock's ERB pastiche time travels to the era before the human race had migrated from Mars to Earth. The origin of the DC Comics superhero, the Martian Manhunter, changed from teleportation to time travel.

Anderson's "Margin of Profit" had Martians but, when the story was revised to fit it into the Technic History, those "Martians" had become extrasolar aliens who had colonized Mars. Every possibility is covered but this time not just by Anderson.