The Guiana Shield, which includes Iwokrama Forest, have several species that are the largest of their kind in the world, or at least in South America. These species are found in relatively healthy populations within Iwokrama Forest but may be extinct, endangered or otherwise vulnerable elsewhere in their historical range. The reference to "El Dorado" is due to the Guianas' association with the myth of a wealthy prince and his golden city. 

Jaguar
Panthera onca

(Photo © A. Holland / G. Duncan)

South America's largest cat; adults weigh 45 to 90 kilos (100 to 200 lbs.); savannah-dwelling male jaguars recorded to weigh more than 136 kilos (300 lbs.) and be 2.5 metres long (8 ft.) from nose to tail tip.
>Learn more about Jaguars

Black Caiman
Melanosuchus niger

 
World's largest of Subfamily Alligatorinae (alligators and caimans); length up to 6 metres (20 ft.).
 >Learn more about Black Caimans

Giant Otter
Pteronura brasiliensis

 
World's largest and rarest otter; length up to 2 metres (6 ft.); weight up to 30 kilos (70 lbs.).
>Learn more about Giant Otters

Harpy Eagle
Harpia harpyja

South America's largest eagle and world's most powerful raptor; females 2x the size of males twice as large as males, at up to 1 metre (3.3 ft.) tall, with wingspans of 2.5 metres (8.2 ft.) and weight up to 9 kilos (20 lbs.).
>Learn more about Harpy Eagles

Arapaima
Arapaima gigas

World's largest freshwater fish; up to 3 metres long (10 ft.); weight up to 200 kilos (440 lbs.).
>Learn more about Arapaimas

Giant Anteater
Myrmecophaga tridactyla

World's largest anteater; body up to 1.2 metres long (4 ft.); tail up to 75 centimetres long (2.5 ft.); weight up to 30 kilos (66 lbs.).
>Learn more about Giant Anteaters

False Vampire Bat
Vampyrum spectrum

(Illustration courtesy of F. Reid)

Largest of bats in Central and South America; wingspans can reach 1 metre (over 3 ft.); weight up to 180 grams (6.35 oz.).
>Learn more about False Vampire Bats

Capybara
Hydrochaeris hydrochaeris

(Photo © A. Holland / G. Duncan)

World's largest rodent; body up to 90 centimeters long (3 ft.); weight up to 30 kilos (66 lbs.).
>Learn more about Capybaras in the
online mammal guide (see large rodents)

Bushmaster
Lachesis muta

Americas' largest pit viper; up to 4,267 millimetres long (14 ft.); nocturnal; it's venom is highly toxic.
>Learn more about Bushmasters and other venomous snakes

Green Anaconda
Eunectes murinus

(Photo © A. Holland / G. Duncan)

World's largest snake when considering weight and length; up to 9 metres long (29.5 ft.); weight up to 200 kilos (440 lbs.); lives in northern South America; non-venomous constrictors - they kill prey by squeezing it to death; excellent swimmers.

Giant South American River Turtle
Podocnemis expansa

(Photo © A. Holland / G. Duncan)

World's largest freshwater turtle; average (70 centimetres (28 in.) long; weight up to 50 kilos (110 lbs.); lives in northern South America.

Puma
Puma concolor

The Puma shares the Iwokrama Forest with other members of the Subfamily Felinae such as the Ocelot and Jaguarundi.
(Camera trap photo from the Brazilian Tapir research project)

Other common mammals found in/near the Forest...
(bats excluded here but many bats and other mammals listed here are described and illustrated in the online mammal guide)