In episode 1, Nigel Marven tries to get a Tyrannosaurus with a young Triceratops. Nigel rescues the Triceratops, but the female Tyrannosaurus doesn't follow. The Triceratops was put in Triceratops Creek. After a flock of Ornithomimus and two juvenille T-Rex were rescued, Nigel and Suzanne have found out that Theo the Triceratops doesn't seem to be very happy about being in the 21st century. Bob creates a machine looking like a Triceratops and Nigel and Bob ride on it and they went into the Triceratops enclosure and Theo was having fun. Theo has calmed down.
Theo has also appeared other episode such as episode 2 where he was grazing on grass. In episode 6, he saw Matilda the Tyrannosaurus chasing Nigel.