I keep reading that Mars had an atmosphere once upon a time, and I guess
some water rushing about, but that it lost most of the atmosphere, and the
water evaporated? because it doesn't have a strong-enough gravity to hold
the thing down.

OK. But how long did it have this atmosphere and the water? I mean, if you
are a planet doomed to have little atmosphere and no running water because
you don't have what it takes gravity-wise, how much time do you have
between the onset of the atmosphere boiling out of the volcanoes or being
acquired by watery meteorites or however the atmosphere got going - how
much time between then and the time the atmosphere has flown into space?

Was that enough time to at least get a few plants started; some lizards
roaming around?