Aaron Lennon gave Everton the lead four minutes before half-time, but Swansea, who lost striker Bafetimbi Gomis to injury, equalised when Shelvey scored from the spot after Seamus Coleman had been penalised for handball.
The result preserved Swansea's nine-point advantage over Everton and allowed the Welsh club to equal their best-ever Premier League points tally of 47m which they achieved in the 2011-12 campaign.
But Garry Monk's side are running out of time to close the gap on the Europa League places, while Everton's hopes of a top-half finish are beginning to fade.
Gomis had scored three goals in his previous two games and he was the first player to threaten, drawing a full-stretch save from Tim Howard with a shot on the turn from 25 yards.
But the France international appeared to injure his hamstring in the act of shooting and had to be replaced by Marvin Emnes.
Everton were also forced into an early change, with Steven Pienaar replacing Leon Osman.
The visitors began to assert themselves and after Lukasz Fabianski had saved a daisy-cutter from Coleman, Lennon put Roberto Martinez's men ahead by firing home from James McCarthy's left-wing cross.
Fabianski had to save at his near post from Arouna Kone moments later, but Swansea succeeded in forcing their opponents back in the second half and with just over 20 minutes remaining, they levelled.
Under pressure from Emnes as he attempted to shepherd the ball out for a goal-kick, Coleman fell to his knees inside his own box in the hope of winning a free kick, but referee Michael Oliver allowed play to continue.
The Irishman reacted by swiping the ball away from the Swansea substitute with his left hand, leaving Oliver no option but to award a penalty, and Shelvey sent Howard the wrong way from the spot.
The two teams could muster only long-range efforts thereafter, with Ross Barkley and Everton substitute Kevin Mirallas shooting straight at Fabianski and Howard tipping a Gylfi Sigurdsson free-kick over the crossbar.– AFP
Original source: Swansea, Everton share the points