Calling Card in Rhyme

An asteroid is what they claim
filled the skies with muddy rain
killed off all the vegetation
left the dinos without ration
only smaller stuff survived
and in time mankind arrived

The rock from space might well have missed
a better thing I must insist
if those big guys were still around
asphalt wouldn't cover ground
the air would not be so polluted
the laws of nature convoluted

Don't lament, there's lots more out there
and scientists without a doubt care
much about what's in the heavens
and think we'll keep on rolling sevens
still, dinosaur-times came up craps
a lesson to us all perhaps

To think about the state of grace
that came to us from outer space
to use our time and use it soon
cleaning up the mess we've strewn
for who knows why and who knows when
a calling-card may come again