Despite so little forest remaining, the Atlantic Forest remains extraordinarily lush in biodiversity and endemic species, many of which are threatened with extinction.
Approximately 40 percent of its vascular plants and up 60 percent of its vertebrates are endemic species, meaning they are found nowhere else in the world. The official threatened species list of Brazil contains over 140 terrestrial mammal species found in Atlantic Forest. In Paraguay there are 35 species listed as threatened, and 22 species are listed as threatened in the interior portion of the Atlantic Forest of Argentina. Nearly 250 species of amphibians, birds, and mammals have become extinct due to the result of human activity in the past 400 years. Over 11,000 species of plants and animals are considered threatened today in the Atlantic Forest. Over 52% of the tree species and 92% of the amphibians are endemic to this area.
The forest harbors around 20,000 species of plants, with almost 450 tree species being found in just one hectare in some occasions. New species are continually being found in the Atlantic Forest. In fact, between 1990 and 2006 over a thousand new flowering plants were discovered. In 1990 researchers discovered a new tamarin, the black-faced lion tamarin (Leontopithecus caissara). A new species of blonde capuchin (Cebus queirozi), named for its distinguishing bright blonde hair, was discovered in northeastern Brazil at the Pernambuco Endemism Center in 2006. A species of endangered three-toed sloth, named the maned sloth (Bradypus torquatus) because of its long hair, is endemic to the Atlantic Forest.