Callahan added four steals while Tarrant had five assists. Josh Davis had 11 points and eight rebounds for the Green Wave (7-2).
Freshman T.J. Carpenter notched a career-high 15 points for the Colonels (1-4).
The win makes Tulane 4-0 on its current homestand, and the Green Wave has now won 19 of 20 all-time showdowns with Nicholls State.
Tulane led 23-12 with just under 8 minutes left in the first half, but the Colonels cut the lead to 30-24 by halftime.
Callahan hit a 3 then Davis made a dunk and two free throws to put Tulane up 37-24 after the break. Nicholls State never pulled closer than eight after that.
Mississippi State freshman guard Malik Newman will withdraw from the NBA draft, but sources told ESPN he might explore other opportunities besides returning to Mississippi State.
Seton Hall sophomore Isaiah Whitehead will stay in the NBA draft and not return for his junior season.
Washington State's trio of Josh Hawkinson, Conor Clifford and Ike Iroegbu have withdrawn from the NBA draft and will play their senior season with the Cougars.
|Stephen F. Austin||18-0||-||28-6|
|Sam Houston State||12-6||6||18-16|