Mapusaurus Rex, typically called Mapusaurus for short, was a contributor on the Topix Dinosaur Forum.
Mapusaurus Rex arrived in March 2012, when many new users began to appear and "feed" trolls, causing a troll crisis. While Mapusaurus Rex stayed out of it at first, and contributed infrequently, he was later accused of being the impersonator of the troll Giganotosaurus Fan, due to his and the impersonator's grammar being similar. Most rejected this and believed Andrink to be the impersonator, while Mapusaurus denied the allegations. He began to grow more resentful of trolls as a result.
In June 2012, many users fled from Topix to Imeprial Palace, although Mapusaurus, despite the large troll presence, continued making contribution to Topix. He often flamed Doctor Facepalm and Crazy Fish during the summer of 2012. Later, in August 2012, as Altanative Whatever, another troll, began to post on the forum, Mapusaurus began to flame even more. He was often infuriated by the trolls, which hindred his ability to make contributions. Mapusaurus Rex was last seen in October 2012, when he left after he got sick of TDF's low security.