Kevin Costner acknowledges his son's acting debut in the 'Horizon' trailer: 'Very proud.'

Kevin Costner has spent decades bringing "Horizon: An American Saga" to life.

He released the first trailer for the four-part post-Civil War drama last week, featuring a new Costner to fall in love with on the big screen: his 15-year-old son, Hayes Logan Costner.

In another video posted on social media Sunday, Kevin lauded his youngest son for being "the best part of the Horizon: Part 1 trailer."

"When it's your movie you get to pick who you hang out with," Costner said in a statement. "Really proud of my son, Hayes, for making his acting debut in #HorizonAmericanSaga."

Costner said, "And thank you to everyone who has showed appreciation for our trailer this week. I couldn't be happier to share this with you." With ex-wife Christine Baumgartner,

Costner has three children: Hayes, Cayden, and Grace. Following 18 years of marriage, the former couple formalized their divorce in February.

In addition to appearing in the picture, Costner directed "Horizon" from a script he co-wrote with John Baird. 

Costner rode out into the sunset from "Yellowstone" and into the American Southwest in the first teaser trailer released last week for "Horizon,"

which was filmed in Utah and produced by Territory Pictures (his production firm) in collaboration with Warner Bros.

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