Oxford University's bowlers toiled throughout the day for little reward on a slow pitch at The Parks after Gregor Macmillan won the toss and put Glamorgan in.
Hugh Morris led the scoring, hitting 125 of Glamorgan's 360 for 5, and Matthew Maynard looked set for a century until he fell to a good catch at the wicket when he had made 86.
They came together at 36 and added 162 off 54 overs for the second wicket before Maynard leg-glanced Macmillan and was snapped up by Chris Townsend.
Morris was suffering a bad back which restricted his strokes, but during a stand of 93 with Tony Cottey he completed a dour and chanceless century which took 277 minutes and contained 11 boundaries.
At Fenner's, Nick Speak upstaged Michael Atherton and John Crawley in scoring a century for Lancashire against Cambridge University.
Atherton, who opened the batting with Speak on a day when 100 minutes' play was lost to rain, seemed preoccupied by events elsewhere, making 20 in almost an hour and a half before being caught at square leg.
It was not until he was out at 46 in the 27th over that the bat began to dominate the ball. Crawley, like Atherton a former Cambridge captain, was immediately into his stride and eventually Speak began to settle into an easy rhythm against some accurate bowling.
They put on 146 for the second wicket before Crawley, having made 74, lost his off stump to give Adam Janisch his maiden first-class wicket. Speak, having scored a century from 180 balls, eventually holed out off Nick Haste, who was easily the pick of the Cambridge bowling.