EXCLUSIVE: AMC pilot Galyntine has a new director. I’ve learned that David Mackenzie, who was tapped to helm the project in March, has left over creative differences. The pilot’s executive producer Greg Nicotero will now also direct.

Galyntine originated with Nicotero who pitched the idea as part of his first-look deal with AMC. He then partnered with Jason Cahill, who wrote the script and exec produces, and Scott Free, whose David Zucker and Ridley Scott also exec produce. The fantasy-action adventure with hints of sci-fi is set in a postapocalyptic future without technology where a band of survivors is forced to adapt to isolation and the challenges of their new world.

Nicotero making his pilot directing debut with Galyntine marks the next step in the evolution of AMC’s relationship with the special effects makeup guru who has designed all zombies on the network’s flagship series The Walking Dead. AMC made a big bet on Nicotero in 2011 when it inked a first-look deal with him and tapped him as co-executive producer and director on The Walking Dead. Since then, Nicotero, repped by WME, Generate’s Chris Pollack and attorney PJ Shapiro, has helmed seven episodes of the zombie drama, including the Season 4 premiere, and is set to direct four more next season, including the Season 5 opener.

Galyntine would’ve marked the U.S. TV debut of Scottish director Mackenzie, known for awards-winning indie films such as Starred Up, Hallam Foe and Young Adam. Both of AMC’s two current pilots have now changed directors shortly before going into production.

Earlier this month, Craig Zisk stepped in to direct Knifeman after Brian Percival pulled out for personal reasons.