The past tense of smelly

This morning, while getting ready for school/work, Hannah was playing with her plastic dinosaur set. They were engaged in a battle and as one or another dinosaur was slain, it was put back into the box (my idea, rather brilliant). As the box began to fill up, I noticed Hannah sniff it and exclaim "eww, pee-youuuuu". Curious, I asked, "does something smell?"

"Yeah, all these dead dinosaurs!"
"They smell? Why do they smell?"
"Cause they're dead!"

Thinking this to be somewhat morbid for a four year old, I ask where she heard that something dead would be smelly.

"At school."
"They told you that dead dinosaurs smell bad at school?"
"Yeah, they're extinct!"

This takes me 3 or 4 seconds.

"Hannah, something being extinct doesn't mean it smells bad...it means there are no more of them left, that they're all dead."

"Oh...I thought the dead dinosaurs were stinky."