Sid is a Diictodon. He was Dr. Cockroach's tenth creature, and his seventh regular creature.
His card winded up in Peru. He activated when a bunch of playing kids kicked the Card Capsule. He battled Sail and drew. He was later revealed to be an 18 on the Power Scale. His capture removed Millipede from the team. Two episodes later, he battled in a battle royale, but was defeated. Twenty episodes later, he was removed from the team by Digger's capture.
The fourth copy of the Crystal Break Move Card was in his Card Capsule, and activated along with him. After his defeat, the card was retrieved by the team.
He is named after a character from the ITV/BBC series Primeval.