I have a smaller yorkie, though not tiny , he is definately not huge...but in my constant research of ancient yorkies and origins or yorkies..before the 7 pound breed standard there were the original yorkie dogs...and they were much larger than thier relatives today, one report I read from a yorkshire historical paper documents a yorkie ancestor that weighed 30 pounds ! Used in hunting and coal mining the dog had to be a hearty breed , and he was, and still is, though so much smaller today due to the smaller ones being popular.I wanted a medium to larger one myself as my other dogs are bigger and very boisterous, so I wanted my yorkie to be able to hold his own...though not a large dog Moe does tend to hold his own, in fact so much so that I have found myself having to protect the others from him! Anyways your 2 are beautiful, and have probably got a kick back to the long gone days when the yorkie dog was a medium sized dog! Here is a link to some other interresting reading.
http://www.petpublishing.com/dogken/breeds/yorkie.shtml