We are talking about a world which is cold, dry, where food is in fairly short supply, and the air is thin. Like Tibet perhaps. But most importantly, this is a place where gravity is low. You would weigh 38% what you do on Earth.
This means that creatures could get much spindlier and more fragile, needing less food; or on the other hand it means creatures could stay as robust as they are on Earth but scaled up to much larger size, with heat conservation advantages.
And what about birds? Would much larger birds be able to fly, despite the low air pressure?
And finally, what about people? Big and robust, or tall and spindly, or small and compact?
