No, it was "proven" by experts that birds represented the largest things that could ever fly. Anything larger was just science fiction.
=============
Put these three indisputable facts together:
One: There is a low limit of weight, certainly not much beyond 50 pounds, beyond which it is impossible for an animal to fly. Nature has reached this limit, and with her utmost effort has failed to pass it.
Two: The animal machine is far more effective than any we can hope to make.; therefore the limit of the weight of a successful flying machine can not be more than fifty pounds.
Three: The weight of any machine constructed for flying, including fuel and engineer, cannot be less than three or four hundred pounds.
Is it not demonstrated that a true flying machine, self-raising, self-sustaining, self-propelling, is physically impossible?
-Joseph Le Conte, Professor of Natural History at the University of California, Popular Science Monthly, November 1888.
===============