Rollingstone has posted a piece on the return of show Community on Yahoo! Screen on March 17th. In the write-up the following was said:
…while Joel McHale “teased” the show’s stacked lineup of “all-star guests” including Keanu Reeves, Matthew McConaughey, Meryl Streep, Julia Roberts, dinosaurs, unicorns and even gargoyles.
I’m not familiar with the show but you can read the piece here.
Note: Den of Geek is also reporting the same thing so I’m assuming this is legit.