Green Ronin’s upcoming revision of its Advanced Bestiary will be compatible with Paizo’s Pathfinder RPG, according to the new Kickstarter project just launched for the book.  The previous edition was created for d20 products; but was used in the development of Pathinder, according to Paizo Editor-in-chief F. Wesley Schneider, who said on the product’s Kickstarter page, "Honestly, we wouldn't have been able to tell the stories we wanted to tell in Pathfinder without the Advanced Bestiary."
 
The Advanced Bestiary will be developed by Own K.C. Stephens, who worked at Wizards of the Coast on D&D 3E and on many RPGs as a freelancer since. 
 
The book is planned as a 264-page b/w hardcover, but page count and interior color could both change depending on the outcome of the Kickstarter, which hit over 80% of its target in the first 24 hours, so appears likely to get into the stretch goals.
 
Advanced Bestiary is not just a dictionary of monsters; rather it functions as an enhancement guide and toolkit for existing creatures, giving GMs and players ways to manipulate monsters to customize them for campaigns of any style or level.  Chris Pramas, President of Green Ronin, explained it thusly, "The Advanced Bestiary will have over 100 templates for the Pathfinder RPG.  Each template can be layered on top of an existing monster to make a variant version with different powers and abilities.  That means the Advanced Bestiary is not just another book of monsters.  It's a force multiplier that makes every bestiary you already own more valuable."

Green Ronin has used Kickstarter before to successfully fund the Mutants and Masterminds 10th Anniversary Edition in 2012, and again in April of this year for their Pathfinder setting Freeport: The City of Adventure.
 
There is a retailer level available at $50 for 2 copies of the book, with estimated July 2014 fulfillment.  Trade release will follow in August.   Pramas said MSRP will be between $39.95 and $49.95, depending on how many stretch goals are met.