The highly decomposed body of the adult elephant was found in the Amchang range of the Sanctuary during routine patrolling, Forest Ranger Ashok Das told PTI.
He denied media reports that the jumbo was killed by poachers and its tusks uprooted and trunk chopped off.
The pachyderm, whose tusks were yet to grow, was not killed by poachers but died due to injuries received on its back during a fight with other members of his herd, Das said.
The injury had caused its hip joint to be broken, he said, adding, its trunk had got detached from the body due to decomposition.
The 78.64 sq km Amchang Wildlife Sanctuary is located in the eastern fringe of Guwahati and is home to animals, birds and reptiles like leopard, elephant, Chinese pangolin, Assamese macaque, hoolock gibbon, Lesser Adjutant, Greater Adjutant, vulture, python, monitor Lizard, Indian Cobra.