Pangea, was originally discredited because at the time

Well because I am unsure what the rest of the question is I’ll have to guess, but it could be:

They had not found dinosaur bones in inconspicuous enough places to support how the two very similar Dinos had been in the two very different locations.
Science had not advanced enough.
They had not looked at the ocean floor discovering the different crusts and how they move.
They simply did not have the evidence for it.

Amethod of procedure that has characterized natural science since the 17th century, consisting in systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses.