They have been named joint vice-captains for the season, and will lead the Crows until van Berlo's return, expected by August.
Coach Brenton Sanderson said the selection panel sought input from coaches, senior players and members of the club's management before deciding that van Berlo should continue as skipper in 2014.
Although he described the 27-year-old as the club's 'standout' leader, Sanderson said the positive to draw from van Berlo's injury would be the experience Dangerfield and Sloane will get as on-field captains.
"Patrick and Rory are both developing into outstanding leaders," Sanderson said.
"They've exhibited an enormous amount of great leadership in the two years I've been at the club and they've gone to another level again this summer.
"If there's any silver lining in Nathan's injury, it's that these two 23-year-olds will be exposed to on-field captaincy roles a bit earlier than they otherwise would have."
Taylor Walker, Richard Douglas, Scott Thompson and Sam Jacobs round out the seven-man leadership group.
It's the first time either Walker or Douglas have held such a position, while Jacobs and Thompson were retained from 2013.
Sanderson said it was an easy decision to elevate Douglas, the 2010 club champion, after a stellar 2013 season.
"In what was a disappointing season for us, Dougy was one guy who really stood up and led from the front, so it was a no-brainer for us to put him in the leadership group," he said.
"With Walker, Dangerfield, Sloane and Jacobs, we've got a great band of 23- to 24-year-olds, who are the future of our footy club and are showing great signs of leadership already."
