It's not just theropods, but all dinosaurs.
They were perceived by some as being like modern reptiles, especially lizards.
Hence you get reconstructions like these with sprawling lizard like limbs:
http://www.google.co.uk/search?q=sp...KUZHZFMPR0QWzlYDgCA#biv=i|1;d|U1VNNKXzst8ITM:
However the defining feature of dinosaurs is an erect posture - see skeleton pictures at
http://dinosaurjungle.com/dinosaur_facts_definition.php
So I think you need a different perception from the start.
Maybe Richard Owen decides to call them dinoaves, terrible birds, nstead of dinosaurs, terrible lizards.
Now to fit Richard owen's world view of biology based on archetypes, for that to happen you need him to name the class based on more obviously bird-like dinosaurs. Which probably means you need to ship a load of Chinese fossils to London zoo in the late 1830s, and even then it's a long shot.
I expect what would happen is you would initially get the names dinoaves and dinosaurs in use, each with their own perceived characteristics, bird-like or lizard-like, and only many years later would somebody realise they are all the same class, and no sprawlers, etc