Incorrect. They were known as the "CowBelles & Beaux" prior to '72. That squad included dudes, which is probably why you saved the photos.
"When the 1972-73 NFL season kicked off that fall, it was a major turning point in Cheerleader history. The Dallas Cowboys introduced their "new" Cheerleaders at Texas Stadium wearing new star spangled uniforms and debuting an innovative and exciting new form of gameday action. For the first time ever, anywhere, jazz dancing was blended with beauty and brought to a football field...and the Dallas Cowboys Cheerleaders were born."