Investigators believe the 39-year-old mistakenly dropped his phone in the statue then he became trapped when trying to retrieve it and died a slow death.
However, there is no obvious indication as to how he originally entered the stegosaurus.
His body was found when a disturbing odour from the papier-mâché figure in the Barcelona suburb of Santa Coloma de Gramenet was smelt by a father and son on Saturday, May 22.
On closer inspection, the dad spotted the corpse through a crack in a rear leg of the statue, BBC News reports.
He then called the police who said the man’s family had reported him missing and no one else is understood to have been involved in his death.
A spokesperson for local law enforcement, Mossos d’Esquadra told VICE World News that the cause of death is yet to be confirmed but admitted investigators suspect the man became stuck head-first, unable to call for help.
They said: “We have no reason to believe that his death is criminal. We think he got stuck in the leg after dropping something.”
Three fire brigade teams were called to the cut-open the dinosaur leg so the corpse could be pulled from inside it.
The authorities are awaiting the results of his autopsy to find out how the man died.