The discovery of fossils clearly ancestral to Misdreavus, if distantly related to Aerodactyl, has raised far more questions than it answered. Misdreavus were long considered the most human of ghost pokemon, lingering in response to betrayals in relationships; how, then, could Flutter Mane fossils appear in Paleocene rocks?
It is hard for any humans alive to comprehend the feelings of a spirit left behind after a mass extinction, and even those pokemon who have perished after contact with humanity experienced nothing like the suddenness that ended the Mesozoic. It is one thing to be the last of a dwindling species, defeated by a new bipedal enemy with superior intelligence and thrown weapons; it is something entirely different to dominate the skies until the day when an asteroid destroyed your entire lineage, leaving the future to Archeops' descendants.
And yet Flutter Mane must surely have dominated the skies for a while longer still, the ghost of an extinct species, shorn of body and beak in its afterlife yet still too powerful for Paleocene birds to drive from the skies. No other fossils of ghost pokemon are known as of this writing, Spiritomb and Yamask's stones being properly considered artifacts, and some paleontologists have suggested the species as a whole is misclassified. The sheer volume of Flutter Mane fossils, moreover, suggests this species must have been truly massive in its heyday, as dominant in their ghostly guise as living pterosaurs were in the Late Cretaceous.
With no other extinct ghost species for comparison, science lacks any coherent theory for why Flutter Mane finally died out – or perhaps one should say "gave up" or "got bored". The very concept of ghost pokemon extinction is disputed; perhaps they only ceased to fossilize and continue to haunt the living, but are mistaken for ordinary Misdreavus.