HOUSTON — The Buffalo Bills have chosen not to retain special-teams assistant Kathryn Smith.

Smith became the first woman in NFL history to serve as a full-time assistant when she was hired by former coach Rex Ryan in Jan. 2016 as a special-teams quality control coach.

She previously was with the Jets, working her way up to college scouting intern in 2005 and then a player personnel assistant two years later. She also was Ryan’s administrative assistant in 2014, his sixth and final season as the Jets’ coach.

After he was hired by the Bills in Jan. 2015, Smith followed Ryan to Buffalo. But after two mediocre seasons, Ryan was fired on Dec. 27.

The Bills, in turn, hired former Carolina Panthers defensive coordinator Sean McDermott as their new coach and on Tuesday announced that several of Ryan’s former staffers would not return for the 2017 season. In addition to Smith, McDermott decided not to retain Ryan’s close friend and longtime defensive coordinator Dennis Thurman along with ex-Jets assistants David Lee, Tim McDonald, Jeff Weeks and Bobby April III. Former Jets players-turned-assistants Ed Reed, Eric Smith and D’Anton Lynn also were let go, along with John Blake, Aaron Kromer, Pat Meyer, Chris Palmer and Jason Vrable.

Morton, Nunn officially added. The Jets on Tuesday officially announced that they’ve hired Saints wide receivers coach John Morton as their new offensive coordinator and former Giants and Browns assistant Robert Nunn as their new defensive line coach.

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Morton, a 13-year veteran in the coaching ranks, has been mentored by some of the best football minds. He spent four seasons with Jon Gruden in Oakland, three seasons in New Orleans with Sean Payton and five seasons with Jim Harbaugh in college and the NFL. He also worked his way up to being Pete Carroll’s offensive coordinator at USC.

Nunn, who replaces former defensive line coach Pepper Johnson, has plenty of experience coaching some of the NFL’s best linemen. He worked with Justin Tuck, Osi Umenyiora and Jason Pierre-Paul while with the Giants from 2010-15 and during that time, the Giants finished fifth in sacks (191).

Nunn, who’s entering his 18th season as a coach, previously worked for the Tampa Bay Buccaneers (2009), Green Bay Packers (2005-08) and Washington Redskins (2003).

Jets coach Todd Bowles fired five assistants in early January. Since then, the team announced the hiring of new defensive backs coach Dennard Wilson and Hall of Famer Kevin Greene as their new outside linebackers coach. But Bowles still needs to add a quarterbacks coach and running backs coach.