While the former British & Irish Lion doesn't make the cut, winger Shane Williams is included just two months after dislocating his shoulder against South Africa in the autumn internationals.
Despite mounting injury concerns, centre Jamie Roberts and Leigh Halfpenny are also included after periods on the sidelines.
There are five uncapped players in total including Turnbull along with versatile back Rhys Priestland, flanker Toby Faletau and front rowers Ryan Bevington and Scott Andrews.
Matthew Rees remains captain while former skipper and conventional back-rower Ryan Jones has been bracketed as a lock alongside Bradley Davies and Alyn Wyn Jones.
A couple of familiar faces return in the form of scrum-half Dwayne Peel and full-back Morgan Stoddart but the likes of Dan Biggar, Tom James, Aled Brew, Tom Prydie, Huw Bennett and Ian Gough all miss out.
Although more players could have been included, Gatland says it was a deliberate policy to name a 28-man squad.
"We have deliberately kept the squad as small as possible and have reverted largely to the philosophy we had during the Grand Slam year in 2008," said coach Warren Gatland.
"We want to keep intensity levels up in training and have ensured that we are not carrying players with injury. Everyone here is fighting fit and able to take a full part and challenge each other for selection.
"Up front, it's well documented that we have lost a couple of players in the front row, but that gives opportunities to others to put their hands up, and we are pleased with the options we have got in the pack.
"The forwards have been going pretty well and we have decided to give a couple of youngsters a chance, but that doesn't mean there is no way back for those who have missed out.
"We are conscious that we need to begin to realise our potential and that means winning some games.
"It all starts against England at the Millennium Stadium [on Friday, 4 February] and they don't come much bigger than that."
Forwards: Paul James (Ospreys), John Yapp (Blues), Craig Mitchell (Ospreys), Ryan Bevington (Ospreys), Scott Andrews (Blues), Matthew Rees (Scarlets, capt), Richard Hibbard (Ospreys), Alun Wyn Jones (Ospreys), Bradley Davies (Blues), Ryan Jones (Ospreys), Sam Warburton (Blues), Jonathan Thomas (Ospreys), Andy Powell (Wasps), Josh Turnbull (Scarlets), Toby Faletau (Dragons), Dan Lydiate (Dragons).
Backs: Mike Phillips (Ospreys), Dwayne Peel (Sharks), Tavis Knoyle (Scarlets), Stephen Jones (Scarlets), Rhys Priestland (Scarlets), James Hook (Ospreys), Jamie Roberts (Blues), Jonathan Davies (Scarlets), Shane Williams (Ospreys), Morgan Stoddart (Scarlets), Leigh Halfpenny (Blues), Lee Byrne (Ospreys).