  Palla & Stahler have recently argued that star formation in Taurus and other
nearby molecular clouds extends over a period of at least 10 Myr, implying
quasi-static cloud evolution and star formation. Their conclusions contradict
other recent results indicating that molecular clouds are transient objects and
star formation proceeds rapidly. The Palla & Stahler picture implies that most
molecular clouds should have extremely low rates of star formation, and that in
such inactive stages the stellar initial mass function should be strongly
skewed toward producing stars with masses $\gtrsim 1 \msun$; neither prediction
is supported by observations. I show that the Palla & Stahler conclusions for
Taurus depend almost entirely on a small number of stars with masses $\gtrsim 1
\msun$; the lower-mass stars show no evidence for such an extended period of
star formation. I further show that most of the stars apparently older than 10
Myr in the direction of Taurus are probably foreground non-members. I also
present birthline calculations which support the idea that the ages of the
stars with masses $\gtrsim 1 \msun$ have been systematically overestimated
because ``birthline'' age corrections have been underestimated; such birthlines
would eliminate the need to postulate skewed initial mass functions. The
simplest and most robust explanation of current observations characterizing the
vast majority of young stars in molecular clouds is that cloud and star
formation is rapid and dynamic.
