What was the evidence that led some to suspect that the continents were once connected?

That the continents seemed to fit together almost perfectly, and if you had a map that had the resources marked on the continents and you put the continents together the resources would all be in groups next to each other.

answ2. But the pangaea supercontinent was just the last in a conjectured series of super-continent followed by break-up. Perhaps at least three cycles.