Great moment in time! But was he roaring or just having a big yawn?
As some readers will be aware, the Mandrill has a strong connection to
the history of computer graphics as this front-on image of a Mandrill's face
was used extensively by computer graphics academics in the 70's, 80's and 90's - http://www.fmah.com/IMAGES/CCOMPRES/MANDRIL/MANDO.HTM
The image may have originally come from the University of Southern California
Signal and Imaging Processing Institute circa 1977 and was commonly used
in various benchmarking tests. After the famous University of Utah "Teapot"
it was probably the most famous piece of iconography in computer graphics.
As Gary suggested, he was actually yawning, not roaring. Still, looks pretty ferocious and wouldn't want to get too close to those chompers. Do have more, just need time to process.
Quite a colourful looking creature, although I wouldn’t want to argue with those fangs! Were these taken through wire mesh, or glass, or did you have line of sight open-air access?
There was a couple of mandrill enclosures. One with a male and a lot of females with babies, and that was behind a mesh cage. Apparently they're female dominated species(1). The male in there was going nuts The open enclosure was just males I think and that's where this guy was.