Hoping to rebound from their road loss to the Cardinals, and missing several key starters, the Cowboys flew to the Edward Jones Dome for a Week 7 duel with the St. Louis Rams.  With Tony Romo recovering from his injured pinkie, he was demoted to back-up for the game, allowing veteran QB Brad Johnson to get the start. In the first quarter, the 'Boys shot first as RB Marion Barber got a 1-yard TD run.  The Rams would go on to score 34 unanswered points with QB Marc Bulger completing a 42-yard TD pass to WR Donnie Avery, along with RB Steven Jackson getting an 8-yard and a 1-yard TD run.  In the second quarter, St. Louis increased their lead as kicker Josh Brown got a 52-yard field goal.  In the third quarter, Dallas continued to struggle as Jackson got a 56-yard TD run.  In the fourth quarter, the Rams ended their domination with Brown nailing a 35-yard field goal.  Afterwards, the 'Boys got their only response as Johnson completed a 34-yard TD pass to rookie TE Martellus Bennett.. How many yards was the longest touchdown run of the game?