Re: As biology goes, sixty million years ago wasn't that long ago and organisms had pretty established patterns.
True...
Which makes you wonder of the possibilities. Maybe life is not that different elsewhere in the universe. Maybe something fell down and was either destroyed, or assimilated into local Earth life (some viruses do leave their genetic mark behind on their host organisms after they've run their course). Maybe nothing's fallen yet, and we're just really lucky or unlucky because of it.
And that's just the stuff off the top of my head. After all, there's got to be billions and billions of possibilities out there :D