(AP) -- A preliminary exam shows that an endangered baby gorilla born nine days ago at Chicago's Lincoln Park Zoo died of head trauma.
Zoo workers discovered the baby gorilla was dead Friday morning, as she was being carried around by her mother.
The zoo says workers allowed the mother, 16-year-old Bana, to keep the baby for several hours "to make peace with what happened." She was a first-time mother.
The cause of death was determined later in the day during a necropsy, the animal version of an autopsy.
The baby's father was a 22-year-old silverback gorilla named Kwan.
The baby was the first Western lowland gorilla born at the zoo since 2005. She had not been named.
In a statement, the zoo says the baby appeared to be fully developed.
Explore further: Female color perception affects evolution of male plumage in birds