Dennis Quaid and Michael Chiklis are officially in the saddle at CBS, boarding the network's untitled cowboy drama based on the life of Ralph Lamb.

The in-demand actors have closed deals to co-star in the 1960s-set CBS TV Studios drama based on the true story of Ralph Lamb, a rodeo cowboy-turned-longtime sheriff in Las Vegas, The Hollywood Reporter has learned.

Quaid will star as Ralph Lamb in the period piece, while Chiklis will play Johnny Savino, a Chicago mob fixer whose entrepreneurial vision for transforming Las Vegas collides with Sheriff Lamb's law-and-order mandate.

Both will be credited as co-executive producers on the project.

If ultimately picked up to series, it would mark Quaid's first foray into series television. The actor previously received Emmy and Golden Globe nominations for HBO's 2010 miniseries The Special Relationship, in which he played Bill Clinton. The Day After Tomorrow star joins a growing cadre of once movie-only actors from Kevin Bacon to Mira Sorvino who recently headed to the small screen.

For Chiklis’ part, the Western would be his first show since ABC’s No Ordinary Family, a Greg Berlanti drama that wrapped in spring 2011. The former Shield star, who inked a development/talent holding deal with CBS, was tapped to star in the network's passed over Conan O'Brien-produced Vince Uncensored comedy pilot last year.

Greg Walker (Without a Trace) and Nicholas Pileggi (GoodFellas) are attached to write and executive produce the cowboy pilot along with executive producer and director James Mangold (Walk the Line). Kathy Konrad and Arthur Sarkissian are on board as executive producers on the project.

Quaid is repped by WME and Hansen Jacobson; Chiklis is repped by WME and Management 360.