Big-headed Amazon river turtle  (Peltocephalus dumeriliana)

The big-headed Amazon river turtle has a grey-brown to black domed upper shell (carapace) with a keel running down its centre, which is pronounced in juveniles, but becomes lower with age. Likewise, the carapace scutes of young adults are marked with growth rings (annuli), but those of older turtles often become worn smooth. The lower shell is yellow to brown, and the neck and limbs are grey to olive. The large, triangular head is also usually grey to olive but may become noticeably white in old adults. Jaws, by contrast are tan coloured, with the upper jaw being strongly hooked and the snout protruding. All toes are webbed (2).