Fossil Island, also known as Kudos Island, is a currently unreleased island. It was mentioned in a lore livestream in October 2012 as a massive project that had been talked about for years but which was not currently being developed. Mod Mark suggested that Fossil Island would be home to one of the Dragonkin.  In the 2014 March VIP Q&A, Mod Osborne commented again that Fossil Island was not being worked on. At RuneFest 2015 Fossil Island was mentioned as a potential contender for an upcoming RuneLabs poll to add a new in-game area. However the poll, which took place in December 2015, was won by The Arc.
- Fossil island was referenced in the 2014 April Fools event. It could be seen as a destination reachable at level 120 Sailing.
- Fossil Island was released as original content on Old School Runescape.