This trade is the root of the Roy Williams (2008) trade tree — the full chain is traced there.
On October 14, 2008, Dallas acquired Roy Williams from Detroit for its 2009 first-round pick (No. 20, used on Brandon Pettigrew) and third-round pick (No. 82, used on Derrick Williams). Detroit's 2009 seventh-rounder (No. 210) went the other way to Dallas, which later traded it to Atlanta — the Falcons drafted Vance Walker at No. 210.
On October 14, 2008, Dallas Cowboys sent a 2009 first-round pick (No. 20, became Brandon Pettigrew) and a 2009 third-round pick (No. 82, became Derrick Williams) to Detroit Lions for WR Roy Williams.