I have a question about the markings on pieds. What is it that makes the borders of the saddles on some snakes smooth and colored like this?:

http://www.morphmarket.com/c/reptile...-pythons/33294

And on other snakes dark and pixelated like this?:

http://www.morphmarket.com/c/reptile...-pythons/43530

Do the smoothies become pixelated with age? Is it genetic? Random happenstance?