As zoos’ goals, designers’ values, and guests’ expectations change, so do the structures seen at the zoo. Exhibit history is not clear cut, and – despite what some may claim – is not inherently linear. Exhibit strategies develop as a result of tensions, both social and operational, imposed from both inside and outside of zoos. This literature review examines the history of zoo architecture by defining six design periods and considering the lenses of race, class, and nature.

The Southern Gastric-Brooding Frog (Rheobatrachus silus) was an aquatic frog that lived in south-east Australia. In 2002, the International Union for Conservation of Nature Red List declared the frog extinct, although no wild specimens had been reported since 1981. As the common name alludes to, the R.
silus was a gastric-brooder, meaning that the female's eggs developed inside of her stomach. Weeks after ingestion, juvenile frogs escape through the mother's mouth. Because no other observed species performs this reproductive behavior, in the early twenty-first century R. silus became a target of
the de-extinction movement that aims to resurrect extinct species. Researchers studied this frog's reproductive behavior and how the eggs and embryos escape digestion. Some scientists claimed that resurrecting this frog could result in future medical applications related to digestion and to reprogramming organ function, as during pregnancy, R. silus's stomach physiologically functioned as a uterus.