My original tumblr post was here. This image was first posted by 70s Sci-Fi Art and comes to us via goddessoftheblackcoast. It appears to be a crop of cover art for an edition of Fletcher Pratt’s Alien Planet.
Cover found here.
Tumblr favorite #2544: Kidnapped into utopia
My copy of “Alien Planet” doesn’t say, but online info attributes the art to Josh Kirby.