I must say I get very frustrated by stories like this. It illustrated Mark Tawain's dictum beautifully:

There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.

It is taking data from one succession, the Burns Fm at Merdiani and exptrapolating to an entire planet. It's taking a tiny fraction of martian history and applying it to the whole history.

Imagine a future earth from which all obvious life has vanished. A probe from the ngrzz'l species of Formalhaut lands on an evaporite deposit deposit (say the Summerville Fm in Utah) and concludes because of the evidence for hypersaline conditions that life was unlikely on the ancient Earth. Meanwhile, just up section is the Morrison Formation, with some of the best dinosaur bones on Earth.

I wish people would stop saying this sort of stuff. People like Andy Knoll should know better.

Jon