Marsupial frogs are found in Costa Rica, Panama, and much of northern South America (on both sides of the Andes), and they occur on the continental islands of Trinidad and Tobago. For many years these frogs were considered members of the family Hylidae, but recent molecular studies have suggested they are distinct enough from the true treefrogs that they belong in their own family. Currently there are 2 genera and 57 species in this family. George K. Noble wrote about the marsupial frogs in his 1931 book The Biology of the Amphibia.

"The Marsupial Frogs, Gastrotheca, employ a single sac, and the young may escape as tadpoles or as metamorphosed frogs. In the case of Gastrotheca, the origin of the sac may be traced to shallow folds bordering the egg mass carried on the back of the female Cryptobatrachus. Once the brooding habit was established in this group of South American tree frogs, it led to marked structural changes in the parent. Less marked changes of the integument have been noted in other brooding frogs, but in no case have emotional bonds been established which make possible the protection of the young after hatching."

Dwarf Marsupial Frog, Flectonotus fitzgeraldi (Parker, 1933) female with eggs in dorsal pouch. Specimen in the upper photo is from central Trinidad, the lower photo was taken in the Arima Valley of Trinidad's Northern Range. The species may also occur on thdoe Peninsula de Paria, Venezuela. Adult females reach 25 mm, adult males are smaller, reaching about 21 mm in body length. This little frog is unusual in that is calls for a relatively short time at sunset. After the eggs hatch in an advanced stage, the female deposits them in a leaf axial pond.