Amerson was injured while attempting to tackle Cowboys wide receiver Brice Butler in the second quarter. He collided with Butler and Raiders linebacker Tyrell Adams, who registered the tackle.
Gehlken reported Amerson was able to walk off the field under his own power.
The 25-year-old made 15 starts for the Raiders last year and finished with 64 combined tackles and two interceptions. Pro Football Focus gave him a 70.7 overall grade, which ranked 62nd among cornerbacks.
Pass defense was a problem for Oakland in 2016. The team allowed 257.5 passing yards per game, 24th in the league, and ranked 25th in pass defense DVOA (defense-adjusted value over average), per Football Outsiders.
The Raiders open the 2017 regular-season Sept. 10 against what should be a dangerous Tennessee Titans offense. Marcus Mariota made nice strides in his second year, and the team added rookie Corey Davis and veteran pass-catcher Eric Decker in the offseason.
Amerson's absence would be felt in Week 1 in the event he's unavailable to the Oakland secondary.