Mmmm, it looks like someone was delivering some of the old time roofing tar in the cardboard buckets and one spilt out and they just painted the floor??
That will be extremely hard to get off.
IDEA: do you know some hard wood flooring guys that have the small "planer" they use on floors. If so, take up the skid rails and let them run the "planer" over it with the steel blades. It may cut it before the stuff has time to get gooey.
