'What do you mean, "Earth was more dangerous before humans arrived"?'
'One word of you bro; "Dinosaurs".' -- AmberFox
Here's the thing about Deathworlds - numerous extinction events make the surviving branches of the evolutionary scrublands stronger and more terrifying than the ones that got wiped out. Sometimes, that isn't always that obvious.
So when Havenworlders see the reconstructed skeletons of saurian life from the increasingly aptly-named Terra, it's understandable that they freak out more than a little. There's nothing like seeing the ossified remains of a Triceratops and subsequently learning that those were "harmless herbivores" from a nearby Human. It's worse when the Human in question is aged 7-10.
Mediks are on hand for the under-prepared. There are even a few Humans who are underprepared for a small child infodumping vast amounts of paleontological information at anyone who asks a simple question.