No, it really doesn't. Your problem is trying to draw this sharp line in between "chicken" and "not chicken." But in reality, such a line doesn't really exist on the evolutionary path of the chicken. Before the chicken, there was the chicken's dad. Dadchicken was pretty similar to the chicken, but not exactly the same. A little shorter or a little faster or slightly different coloring or whatever. But still a chicken, right? Well grandad chicken wasn't the same chicken either. A little, little bit more different from the chicken than dadchicken was from the chicken. Greatgrandad chicken was a little bit more different than that, even.
If you repeat this for a few hundred thousand generations, your end result is something that doesn't really look like a chicken any more. In fact, if you put it together with a modern chicken, it wouldn't even be biologically compatible anymore. At some point, the DNA has become too different to interbreed properly. But each successive generation was pretty much the same as the next. So where did it become Not A Chicken?