When citing a paper with a lot of authors; is it OK to shorten the author list in the references section?
Every citation style has some threshold at which it is OK to change a long list into an "et al." citation ("et al." is an abbreviation of the Latin "et alia" meaning "and others").  The particular threshold depends on the citation style, but if you've got half a page of authors it's certainly over any reasonable threshold.

You then simply convert your citation of, e.g.:


  A, B, C, E, ... , Z, "Massive Joint Study," Journal of Big Science, 1(4), 2012.


into:


  A, et al., "Massive Joint Study," Journal of Big Science, 1(4), 2012.