Beaumont and Troutman combined to shoot 72.2 percent (13 of 18) from the field. Sebastian Koch contributed 16 points, hitting 10 of 12 from the line -- 5 of 6 in overtime -- for the Phoenix (18-8, 11-3), who have won three straight and 10 of 11.
The Catamounts led 64-61 with 2:11 left in regulation on Tankelewicz's 3-pointer. Troutman hit 1 of 2 foul shots and Jack Isenbarger hit both of his to tie it.
Catamount Josh Mendenhall's layup tied it at 69-all with 2:21 remaining in overtime, but Elon ran off seven straight points to secure the victory.
Colorado State graduate transfer John Gillon has chosen Syracuse, giving the Orange a potential starter at point guard entering the 2016-17 season.
DeSean Murray, who averaged 20.2 points as a sophomore at Presbyterian, will transfer to Auburn to play for coach Bruce Pearl.
Former Kentucky guard Ed Davender, the only Wildcat with at least 1,500 points and 400 assists, has died. He was 49.