Leaders Chesterfield went into the game at Glanford Park with a three-point buffer over their hosts, and left with that gap intact thanks to Eoin Doyle's penalty in first-half stoppage time, which cancelled out Sam Winnall's 15th-minute opener for Scunthorpe.
Third-placed Oxford United missed out on the chance to make up ground on the top two as they were held to a 1-1 draw at struggling Bristol Rovers.
James Constable put Oxford ahead after 10 minutes, but the visitors were denied a win that would have put them second when John-Joe O'Toole struck six minutes from time.
Despite the disappointment, managerless Oxford can take comfort from the fact they have now gone 16 League Two away matches without defeat.
Rochdale and Burton Albion remain hot on their heels following respective wins over AFC Wimbledon and Morecambe.
A Scott Hogan hat-trick - scored in 16 second-half minutes - gave Keith Hill's side a comfortable 3-0 victory, while Burton were grateful for substitute Zeli Ismail's 72nd-minute strike in a 1-0 triumph.
Bottom club Northampton Town's woes continued as they went down 2-0 at home to Plymouth Argyle, for whom Reuben Reid and Lewis Alessandra struck, while seventh-placed Southend United were beaten 2-1 at Mansfield Town.
Samuel Clucas and James Jennings put the home side two up prior to Ryan Leonard's 90th-minute consolation for Phil Brown's side, who tasted defeat in the league for the first time in nine matches and had Conor Clifford sent off.
Hartlepool United won 2-0 at Dagenham and Redbridge, while Exeter City needed a stoppage-time equaliser from Liam Sercombe to rescue a point in a 1-1 draw with Portsmouth.
Wycombe Wanderers and Accrington Stanley played out a 0-0 draw, as did York City and Cheltenham Town, while Torquay United's game with Bury was postponed because of a waterlogged pitch.
