TORONTO - Officials at the Toronto Zoo say staff who worked with Tara the elephant are devastated after the animal described as the matriarch of the zoo's elephant herd died unexpectedly at age 41.

Tara was found lying down Monday morning and staff could not get the 3,855-kilogram animal back on her feet.

They say Tara had not exhibited any recent signs of ill health, and that a post-mortem will be conducted to determine a cause of death.

The average lifespan of elephants in captivity is 40 to 45 years.

The largest of the zoo's elephants, Tara was also "the boss."

The African elephant arrived at the Toronto Zoo in 1974, shortly after it opened.

"She had a good relationship with all her keepers," Eric Cole, supervisor of the zoo's African Savanna section, said in a release.

"She loved to have her face rubbed and would lower her head for this activity."

"All the staff who worked with Tara are devastated by this unexpected loss. We will miss her greatly."