Leaders Falkirk picked up where they had left off with a 2-0 win over Montrose to extend their lead at the top of the table as Scottish League One action resumed.
The Bairns had last played on January 2 before the league was paused under new Scottish Government coronavirus restrictions.
With 20 minutes left, Thistle substitute Joe Cardle broke the deadlock, but Megginson struck in the 82nd minute to secure a point.
Forfar moved off the bottom with a 1-0 win at Dumbarton, which came courtesy of a rather unfortunate own goal from Ryan McGeever.
The visitors took the lead in the 57th minute when Sons keeper Sam Ramsbottom sent a clearance against defender McGeever and the ball bounced back into the net.
Clyde sank to the foot of the table on goal difference after a 3-1 home defeat by East Fife.
Nathan Austin gave the visitors the lead five minutes before half-time and midfielder Danny Denholm headed in a second in the 55th minute.
Ryan Wallace nodded in a third goal in the 68th minute, with David Goodwillie's goal in the final minute providing little consolation for the hosts.
Peterhead beat Airdrieonians 1-0, with the visitors playing almost the whole game with 10 men.
The home side's extra man was eventually made to count when Jordon Brown broke the deadlock in the 66th minute.