Bummer Dude. Glad you are OK. <40F and wet is primo black ice conditions. The temp is at thermometer height and doesn't take into account that the ground 5' below that is still frozen solid and flash freezes air moisture to the nastiest slippery surface imaginable. You can't even see the ice, sometimes, it is so thin (I have had eyeball level view of every little interstitial space in the pavement). But it is still a frictionless surface for bikes and pedestrians. My wife wiped out on that kind of black ice once spectacularly enough that a car in full control stopped and when the driver got out to check on her he did the full Charlie Brown feet above his head reverse superman. It's like the flipside of bikes don't hydroplane.

Anyway, very glad you are OK enough to type about it.

edit: and, yeah, studded tires do defeat that