I'm not sure about the Catapultasaurs but when the item is used on minotaurs, the minotaurs take ~2/3 of their damage immediately (numbers around 200 depending on what flags and upgrades the teams have) and still have health left while in the air; they only lose this remaining health when they hit the ground. I don't think I've ever seen units get up after being thrown in the air, so thrown in the air must mean death (this would have to be tested though).