Ambystoma—Mole Salamanders // Anura—Frogs and Toads
Those amphibians of our region that are represented as fossils are tied to water for reproduction. Eggs of these forms are laid in water and hatch into a larval, aquatic stage (the tadpole or pollywog). The larvae eventually undergo a gradual metamorphosis with some structures, such as external gills, being absorbed and other structures, such as legs, forming. Lacking waterproof skins, the adults must stay in habitats moist enough to prevent desiccation.
Our amphibians fall into two taxonomic orders: Caudata (salamanders) and Anura (frogs and toads). The former is represented in the regional fossil record only by the genus Ambystoma. Adult salamanders often are found some distance from water, moving about during wet weather and otherwise sheltering in high-humidity microhabitats such as rodent burrows. Various anurans have been recovered from fossil sites within the region. As adults, some, such as the ranids and hylids, are tied closely to water, receiving some protection from terrestrial predators and from drying out. The adult spadefoot toads, however, spend much of their time in suspended animation underground except during the rainy season and generally enter standing water only for reproduction. All of the amphibians presumably would benefit from increased effective precipitation.
Last Update: 3 Nov 2008