Turner carded an even-par 70 at the Sunningdale Golf Club in Berkshire.
His balanced round included four birdies and four bogies.
Fellow New Zealander Grant Waite fired a three-over-par 73.
German great Bernhard Langer made an impressive start to the defence of his title and ended as part of a record eight-way tie for the lead after the opening round.
Langer ripped up the record books on his own 12 months ago as he raced to an unprecedented 13-stroke victory at Royal Porthcawl.
Yesterday, he had to share another piece of history following a five-under-par opening round of 65.
That total was matched by the American quintet of Michael Allen, Bart Bryant, Marco Dawson, Lee Janzen and Jeff Sluman, Spaniard Miguel Angel Jimenez and Lianwei Zhang, who also created history by becoming the first Chinese player to compete in the Senior Open.
The previous record for the most players tied for the first-round lead in the Senior Open was four, which happened in both 2004 and 2007.
Langer is bidding to equal the record of three victories in the Senior Open, held by Gary Player and Tom Watson.
Despite not hitting top gear, the 57-year-old former Ryder Cup captain moved ominously to the top of the leaderboard with six birdies against just a single bogey, which came on the sixth hole.
Welshman Mark Mouland, American Brian Henninger and Argentine Cesar Monasterio were one shot behind the leaders, while Watson and Scotland's Colin Montgomerie were among eight players tied on three-under-par.
Montgomerie, the three-time senior major champion who finished runner-up to Langer last year, posted five birdies in his round of 67, but a double-bogey six on the par-four 11th hole cost him a share of the lead.
• New Zealand's Ryan Fox finished with four birdies and an eagle in his final six holes to smash the course record with a nine-under-par round of 62 and lead by one from Robert Coles after the first round of the Le Vaudreuil Golf Challenge.
Fox made his major championship debut at St Andrews last week, finishing in the top 50 of the British Open after a fine 67 in the final round, and he continued that form in France.
The 28-year-old is only playing in his fourth European Challenge Tour event but recorded top-10 finishes in his first two tournaments.
