Because the magical lake lies under a desert, the folk must have adapted to high temperatures and long distances. Desert animals are skinny and have some kind of a cooling system to keep waterloss to minimum.
Camels have long skinny legs and wide feet.
http://news.xinhuanet.com/english/2009-05/14/xinsrc_432050614130414004951.jpg
And so do jerboas. Though jerboas jump and camels walk.
My character is this humanoid that lives in the desert. They're friendly and peaceful and can run really fast to catch food or something. They also wear some kind of masks because the sun has gotten harsher lately. There's some kind of a global warming kicking about, which also explains why they're so dependent on the magical lake.
I was also thinking about making the character big ears like the jerboa. Jerboas like many other desert animals have big ears for cooling. The large areas of thin skin cool the blood when it circles through in the earlobes. Big ears will also make the creature less scary.
The character has long arms even though it's not very efficient for running. However humans and monkeys are the only ones with long arms and fingers. This type of animals are the smartest ones in the world so giving the character the ability to build things with his arms makes him "more humanlike" and smarter.
The anatomy is a mix of humans and dinosaurs.
http://www.nhm.ac.uk/resources/nature-online/life/dinosaurs/dino-directory/colour/src/Chindesaurus.jpg
