The other reason I was initially confused, but reading this thread helped, is that by presence of bones in the cave they don't just mean that there aren't any bones lying around, brought in by cavemen or bears dying in the cave. They imply that the cave is basically not accessible normally and what would be found in it (bones, fossils etc), if there was anything, can only come from the time when those mountains were formed. I think... Maybe that was obvious for some people.

The original sentence is consistent with the assertion that the mountains had formed before the first boney ancestors of dinosaurs evolved. This is also consistent with the presented timeline.

The correction would mean that the mountains may be older or younger than dinosaurs, because they are only older than bones, and the article is deafeningly silent on the issue of whether dinosaurs had bones.

It's a failure of literacy on the poster's part, hence the downvotes.

Mountains.age !> dinosaurs.age, thus mountains.age <= dinosaurs.age

mountains.age > bones.age

So dinosaurs.age => mountains.age > bones.age

And dinosaurs.age > bones.age

His logical reasoning skills are sound though, as is his sarcastic humor.

This is not the poster is pointing out.

It's basically two booleans that don't go together

Is the mountains older than the dinosaurs = false

Is the mountains older than bones = true

They should both be true, but the writer had the first be false, hence leading to all dinosaurs being boneless. I guess it's a colloquialism in the English language, otherwise all y'all wouldn't had downvote the poster for being pedantic