AITAH for telling my coworker’s toddler that dinosaurs still exist and live in Canada, just to mess with him?

My coworker brought his 4-year-old son to the office one day, and this kid was full of questions. I was bored. So I told him that dinosaurs faked their extinction and moved to the forests of Saskatchewan to live in peace. Kid apparently drew a 12-page dinosaur survival zine and refuses to go to preschool now because “he’s training for dino tracking.” Now my coworker’s mad at me, and HR said I might need “retraining.” AITAH for adding some sparkle to the kid’s life?