Toughie, the world's last-known Rabbs' fringed-limbed tree frog (Ecnomiohyla rabborum), has died at his home at the Atlanta Botanical Garden.

The death of Toughie comes four and a half years after another Rabbs' fringed-limbed tree frog died at Zoo Atlanta. Both frogs were rescued in Panama while scientists were trying to investigate a bacteria that killed a majority of the frog population in the world.

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Jonathan Kolby, the director of the Honduras Amphibian Rescue and Conservation Center, said that since the Rabbs' fringed-limbed tree frog remain high up in the trees, the species can be difficult to find. In fact, 

The Rabbs' fringed-limbed tree frog species was not discovered until the year 2008, a few years after the frog was rescued during a mission by the Atlanta Botanical Garden in 2005. Because of the deadly chytrid fungus, scientists suggests that it is unlikely that any of this frog species would be surviving in the wild.

There is currently an amphibian extinction crisis happening in the world. The Scientific American said that the organization considers Toughie as a public ambassador for all the frog species that are going extinct. Mark Mandica, the head of the Amphibian Foundation who has worked with Toughie for the past seven years, said that the Rabbs' fringed-limbed tree frog is not the only species disappearing, but a lot more.

Meanwhile, Joel Sartore, a photographer leading the "Photo Ark Project" which aims to showcase the planet's diversity and encourage people to help fight extinction, said that the death of the last remaining Rabbs' fringed-limbed tree frog is a sign that the world is slowly losing a large number of plants and animal species.

"We're on track to lose half of all species by the end of the century," Sartore said.