Lindsey and Thomas could play Thursday against the San Diego Chargers, although they will not have practiced.
The Cowboys had only three healthy corners -- Orlando Scandrick, B.W. Webb and Terrance Mitchell -- at Tuesday's practice after Tyler Patmon was forced to the sidelines with a sore hip. Morris Claiborne (knee) will not play on Thursday and Sterling Moore's availability is in question because of a groin injury. Brandon Carr is expected to report to camp after Thursday's game following the death of his mother.
Lindsey has spent time with several teams, most recently with the New Orleans Saints last year. Thomas was with the Saints as an undrafted free agent in 2012.