It seems from my understanding of the Shulhan Aruch (Y"D 181:9) that the picture above is the Shiur of the Peya. However it seems like most people say it goes until the bone like the picture below.
What is the source for this Minhag (if there is one)?
The Shulchan Aruch that you have quoted (YD 181:9 as well as :1) defines "below the ear" as the place where the jawbone juts out (palpate as you open and close your mouth). This is based on Rashi in Makkos 20a.
You can see the obvious (unintended) ambiguity.
Reb Moshe Feinstein is quoted by Rav Shurkin and Rabbi Belsky as explaining the Mechaber in the shulchan aruch as only referring to someone who is in doubt where his hair of his head ends and the hair of his beard begins. This unsure person must be stringent and treat all the hair in front of his ear as peyos harosh out of doubt. However someone who can tell, either by the difference in hair type, or if he remembers where his peyos harosh ended before his beard grew in, does not need to worry, and can treat each section with it's own halakha.
As an aside, the top of the peyos inyour picture are too low by most standards. Click on the links in the comments.
