Chinese state media reported the last known female Yangtze giant soft-shell turtle has died.
She was estimated to be over 90 years old.
While the turtle died around 24 hours after researchers tried to artificially inseminate her, they don't believe the procedure caused her death.
Zoo officials have been trying to breed the turtles in captivity since 2006. Several eggs were laid, but none hatched.
A necropsy is set to be performed to determine the exact cause of death.
Unlike other critically endangered species' deaths, this one took place in a zoo. While other animals have become extinct in the wild, there are still animals of their species living in parks and zoos that can be used for breeding.
For the Yangtze giant soft-shell turtle (Rafetus swinhoei), this death was part of the last known breeding pair living in captivity. The turtle lived at Suzhou Shangfangshan Forest Zoo in eastern China's Jiangsu Province.
There are two known Yangtze turtles living in the wild, but the gender of only one, a male, is known.
One turtle, the male, lives in Dong Mo Lake, Vietnam. The other, that has not been examined to determine gender, lives in Xuan Khanh Lake in the outskirts of Hanoi, Vietnam.
Plans to examine that turtle have not been announced and would require cooperation between conservationists in Vietnam and China.
With the death of the turtle, named China Girl, all hope of saving the species may have been lost.
According to Dr. Xie Yan, former director of Wildlife Conservation Society (WSC) projects in China:
"When it comes to saving species from extinction, humans are truly powerless."
Indeed, when only four animals remain alive is much too late. Identifying and conserving species and their habitats has to occur long before such a critical state.
Yangtze giant soft-shell turtles are one of the biggest freshwater turtles currently on Earth. Adults can grow a shell larger than a yard (1 meter) in length and weigh over 220 pounds (100 kg). Their life span has been recorded to reach an astounding 400 years.
The critically endangered species inhabited the Yangtze and Red River for millions of years. The turtle served as the inspiration for the mythological creature "Bi Xi" or "Ba Xia," sixth son of the dragon in ancient Chinese beliefs.
The earliest human records of the Yangtze turtle go back before 1,000 B.C., or over 3,000 years ago. But over hunting and loss of habitat doomed the species.
Preservation of habitat is still the best way to keep species from going extinct.
According to Zhao Zhonghua, chief China representative of World Animal Protection, a United Nations general consultative organization:
"When the wholesome natural habitat is well protected, it is not only one species that will benefit but the entire biosphere including natural resources like water and all species that form part of the ecosystem."
That includes one species every human should be concerned about: our own.
