Marks, 26, started the season in the Kansas City Royals' organization, before being traded to Oakland on June 5.
Marks has been added to the 40 man roster and optioned to AAA. To make room for Marks on the 40 man roster, the Rangers have transferred Prince Fielder to the 60 day disabled list.
Marks was the A's 3rd round draft pick in 2009 out of the University of Louisville, and was sent to Kansas city after the 2010 season as part of the David DeJesus trade. Marks has just one major league appearance in his career. In 165.1 career innings at AAA, he has a 5.12 ERA, with 146 Ks and 76 walks.
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