Originally Posted by mander
I'm pretty sure that track ends are much older, maybe someone else can confirm this. In my understanding (forward facing) drop-outs were invented so that you could get the wheel off without derailing the chain, i.e. drop the wheel out of the chain loop.
Can anyone give a more specific timeline or correct me if I'm wrong here?
If you want to get hard-core technical, the oldest bikes were closer to track ends than horizontal dropouts.
But odds are, if you see a bike on the street, and it's got horizontal dropouts, it's not new.