Set in a volcanic pre-historic valley, Volvic "Jog" from WCRS pits man against dinosaur in a primeval game of cat-and-mouse.

Only in this scenario the typical roles are reversed as a cheeky caveman looking for adventure and armed with a bottle of Volvic goads a T-Rex into action. Fuelled by Volvic's "volcanicity," the caveman succeeds in outrunning the exhausted beast, only to unsettle the scales of three more.

Great Guns directing team Who? put London's Framestore CFC to the task of creating a dinosaur that pushed the boundaries of previous reptilian efforts. For Framestore CGI supervisor Andrew Daffy that meant getting their hands a little dirty.

"The directors wanted something that had never been done before," says Daffy. "We decided that we wanted to make him a little more scuffed up, as if this thing had been around for 50 years and the mud has just been ground into all the cracks of its skin. And you also think, it must have been in a few fights, so I wanted some wounds dried up."

Given Framestore CFC's extensive experience with dinos (they created the lizards for the Walking With Dinosaurs TV series), Daffy and his team referenced the best bits of dinosaurs that have been done and used the basic skeleton structures from previous productions.

The basis for creating the personality of the creature came from what Daffy describes as a moving storyboard. "The directors put a mood board together. They wanted a really menacing T-Rex but with humor and for it to look quite dopey," he says. "They found shots from different films, including old plasticine animated things and they cut it all together."

Shot in South Africa over two days, the shoot was in peril of being rained out. Luckily, the sun met the call. However, the uneven topography provided challenges for 3D.

"The hardest thing was to cast a shadow that don't exist onto grass because it's on so many different layers," says Daffy, noting that the shot with the T-Rex coming over a hill was the most troublesome. "Normally we do a run cycle, which is on the ground, but making him go on a bumpy terrain was difficult. We gave [the compositors] the shadows on a flat surface as if there is no grass and they basically had to separate different elements of grass and slowly fade in the shadow. We had to use a straight-ahead forward animation approach rather than cycle animation."

Framestore CGI artists responsible for the dinosaurs were Daffy, Jamie Isles, Martin Parsons, Stephen Enticott, Gwilym Morris, Richard Dexter and Don Mahmood. Inferno artists were Stephane Allender and Ben Cronin; Allender was SFX supervisor; Dave Ludlam was on Spirit, and Lara Hopkins and Helen MacKenzie were post producers. Agency producer was Ginny Wood and Great Guns producer was Sheridan Thomas.