Why was women's Olym 1500m quarterfinal cancelled?

There was to be a quarter final today (Aug 19). I believe it was to be 3 heats of about 16 runners each (same as in '04). But for some reason that was cancelled.

Now both the IAAF and IOC schedules show a two heat semifinal on Aug 21st. Unless they somehow have a much smaller field than in 2004, they are going to have to place 40-48 entries into just two heats. That's crazy crowded for a 1500m race.

I just went to IAAF's entry list at:

http://www.iaaf.org/oly08/results/eventCode=3659/racedate=08-21-2008/sex=W/discCode=1500/combCode=hash/roundCode=e/entrylist.html#det

This entry list is much larger than an approved start list, but nevertheless it contains 35 runners with the Olympic "A" std (4:07) and another two with the "B" standard (4:08) -- where the country had no "A" std. athlete. Also, a few countries might be able to enter a runner without even the "B" std. Russia had 3 entries here, but I'm not sure these backups got approved in time after the urine swapping scandal. So it looks like we have about 40 entries being put into just two 1500m semifinal heats.

I've never seen more that 16 runners in an international 1500m race. Does the IAAF/IOC have a size rule on this?

Anyone know more about this?