f intelligent species only last 100,000 years on average, they are biological “flashes in the pan”. But if they are as durable as horseshoe crabs or coelacanth fish, at 450 and 400 million years.
I don’t see any specifies, no matter how intelligent at their peak, making it past 20M years. Stuff happens. To me, the most compelling scenario comes from Arthur C. Clarke (who was no slouch). After some period of “intelligence” (supposing the civilization does not destroy itself). It evolves to a point where it basically becomes one with the cosmos. That is, it transcends the need for biological or even mechanical bodies to hold their consciousness. Such an advanced consciousness would probably care nothing about the concerns we primitive biologicals hold so dear (eating, sex, the pursuit of wealth & power, etc). In short, it would be as if an ant tried to communicate with us.
It’s been noted that animals that evolve fastest are the most parasitized and isolated from each other. However, horseshoe crabs do have at least some parasites.
Jellyfish, another ancient organism, may have a trick up its sleeve, for at least one jellyfish, called the “immortal jellyfish”, after reproduction reverts to its juvenile form, so does not die of old age.
http://en.wikipedia.org/wiki/Turritopsis_dohrnii