Bertram Collacott

Bertram A Collacott operated the Silurian pet, or "Bertram the Friendly Monster", and served as an uncredited visual effects assistant on Doctor Who and the Silurians.

The dinosaur was listed on script cast lists as "Bertram, the Friendly Monster", after Collacott, and played by "himself". Oxygen had to be pumped into his rubber dino suit during filming. (REF: Who-ology)