This Golden Demon winning Duel was on display in Warhammer World back in 2007.
It comprises a Space Marine Chaplin on a bike fighting an Eldar Exodite on a giant lizard.
The Exodites were a concept that had Eldar using giant lizards as mounts and large mounts for weapons (in a similar way to Elephants or Squiggoths). It was never taken further by Citadel, though some Epic concepts were sculptured and cast, but never went on sale. The concept proved popular with some and as a result there is an unofficial codex out on the tubes and some lovely models such as this one.