Dayton (22-9, 10-6 Atlantic-10) took control midway through the first half with a 12-0 run capped by a three-point play from Kyle Davis that made it 24-10 with 4:25 to go before the break. The Flyers took a 34-19 advantage into halftime and never trailed again.
Vee Sanford contributed 14 points and Jordan Sibert added 12 for Dayton, which out-rebounded Richmond 33-26 and held a 6-1 takeaway advantage to close out the regular season with three straight wins.
The Spiders (18-13, 8-8) narrowed the gap to single digits on a Terry Allen layup that made it 52-44 with 5:40 left, but it was the closest they would get.
Kendall Anthony led Richmond with 20 points and Allen finished with 17.