Chatmon also grabbed nine rebounds as the Kangaroos (3-3) had a 38-26 advantage on the boards. Nate Rogers added 13 points for UMKC, which was playing for the first time since a 91-45 loss at No. 4 Ohio State on Nov. 23.
Thomas Staton scored 11 and Kirk Korver had 10 points for the Kangaroos.
P.J. Hubert led the Jaguars (3-5) with 18 points. Donovan Gibbs had 14 points and eight rebounds, and Mitchell Patton and John Hart scored 10 apiece for IUPUI.