Salientia

Salientia (Latin salire, salio meaning "to jump") are a total group of amphibians. This group includes the order Anura, which are frogs and toads, and some extinct early frogs. These animals are special because they can hop or leap. This way of moving makes them different from other amphibians.

The oldest fossil "proto-frog" was found in the early Triassic in Madagascar. These fossils help scientists learn about how frogs and toads have changed over many years.

Even though these fossils are from the Triassic period, molecular clock dating shows that Salientia might have started even earlier—in the Permian, about 265 million years ago. This means the ancestors of today’s frogs and toads lived long before the first dinosaurs.

Characteristics

Very few fossils of early salientians have been found, so it is hard to know their exact features. Some bone arrangements in their chests and spines give hints, but they are not always clear. Early proto-frogs came from ancestors called temnospondyls. Their bodies, like their pelvises and back legs, were probably better for swimming than jumping. These early frogs likely grew their main traits during the Mesozoic or early Tertiary periods. Today, families like Alytidae, Pipidae, and Pelobatidae live in special places, while harlequin frogs are found in Central and South America. Groups like Ranidae and Bufonidae probably spread from tropical parts of Africa and Asia.

Evolution

Scientists study how frogs, salamanders, and caecilians (a group of limbless amphibians) evolved and how they are related. Some studies suggest that salamanders and caecilians are more closely related than to frogs. These groups began to separate long ago, before the continents we know today moved apart.

One important fossil, Gerobatrachus hottoni, found in Texas, lived about 290 million years ago and shows features of both frogs and salamanders. Another early frog ancestor, Triadobatrachus, lived in Madagascar around 250 million years ago during the Triassic period. It looked a little like a modern frog but had differences such as more body segments and separate leg bones.

Species

The earliest known salientian, a group that includes frogs and their close relatives, is Triadobatrachus massinoti. This ancient creature lived in the Early Triassic period, about 250 million years ago, in what is now Madagascar. It had many features similar to modern frogs, but also some differences, like more bones in its back and a short tail.

Other early frogs, such as Czatkobatrachus, Prosalirus bitis, Vieraella herbsti, and Notobatrachus degiustoi, lived around the same time or shortly after. These animals helped scientists understand how modern frogs evolved from their ancient ancestors.

Phylogeny

Salientia is a group of amphibians that includes frogs, toads, and some ancient "proto-frogs." These proto-frogs are more closely related to modern frogs than they are to salamanders and newts. The oldest fossil of a proto-frog was found in Madagascar from the early Triassic period. Scientists think these animals might have first appeared even earlier, perhaps around 265 million years ago.