Back with another question about a problem uncovered in my 1881 Victorian...

I'm taking up some nailed-down thin plank flooring in the guest room that's in horrible shape and ran into a paper underlayment (feels like stiff construction paper, tan in color, not glued, comes up easily.) I stopped work because I know a lot of older liners and underlayers on vinyl and wood floors can contain asbestos, but I've gotten inconclusive answers not just on whether this material is toxic but exactly WHAT it is--it's not tar paper...maybe it could be rosin paper?

The floor would have gone down in the early 1960s...right in the bullseye for asbestos use. I know it's probably nothing to worry about but I'm doing 98% of this renovation DIY and I don't want to contaminate my home.

Thanks in advance for any help!