The Silurians (Homo reptilia) were Earth’s first intelligent inhabitants, cold-blood reptilians with a lifespan of over three centuries who developed a civilization at least 300 million years before human beings evolved.
River Song had Grayle worked out from the word go. Called him a ‘crime boss with a collecting fetish’. He was a tough guy, sure, but when he kidnapped River he didn’t figure he was starting to collect trouble. A lot of trouble.
Gangers were developed to work in environments too dangerous for people. Controlled remotely by a human operator they soon saved lives and money and most believed a Ganger was simply a tool, little more than a fork-lift truck.