I think it was less than 400 million years. :’) But even so, it’d be weird to have a reunion for the organization... and to arrange the menu...
Unique in the animal kingdom, with a saga steeped in science and popular imagination, the fabulous Coelacanth ("see-la-kanth"), that 400 million year old "living fossil" fish, swims on- a biological Time Machine. Pre-dating the dinosaurs by millions of years and once thought to have gone extinct with them, 65 million years ago, the Coelacanth with its "missing link" "proto legs" was "discovered" alive and well in 1938.
They date back 400 million, but were believed to have been extinct 65 million.
I had a student once ask, "If they were extinct so long, how did they come back?"