"Meet the Brazilian Flea Toad: World's Smallest Vertebrate"
Biologists have confirmed that the Brazilian flea toad, Brachycephalus pulex, is the world's smallest vertebrate, with an average male body length of slightly over 7 millimeters. The tiny frog, found only in southern Brazil, was previously thought to be a toad. The researchers suggest that there may be even smaller vertebrates yet to be discovered, but note that there are likely limits to how small frogs can be due to survival challenges.