No thanks, I’m trying to give them up.
Bison? Not very long, but a distinct difference between front and back.
It’s impossible to know what selective pressures were at work to give us a mane, but it doesn’t seem to be very efficient for insulation or as a sun screen. (Maybe if it grew in the shape of a cooley hat…) I suspect that it was socially or sexually selected for. If that’s right, then it’s a completely arbitrary feature; any other humanoid would be very unlikely to evolve the same thing. On the other hand, I could buy the argument that a display feature on an upright creature might be likely to occur on its head.
Display features are most likely to occur on the head of almost any creature, since that’s where the eyes are and because of that is the part of the body most likely to be directed towards another individual of the same species. Crests and other types of display features are found on the heads of many mammals, birds, and reptiles (including many dinosaurs).