500 million year old gene...a little misleading. The gene was produced recently. It’s a best guess, based on today’s sequences, at what the sequence was 500 million years ago.
Considering it 'evolved' a little differently than they thought it would, maybe their best guess wasn't on the money either.
The REALLY interesting point is that no matter what the conjured up to start with (whether they were correct or not), it seemed to figure out what to do to adapt.