Salientia

Salientia (Latin salire, salio meaning "to jump") are a total group of amphibians that includes the order Anura, frogs and toads, and various extinct proto-frogs that are more closely related to frogs than they are to Urodela, salamanders and newts. These animals are known for their ability to hop or leap, which is a special way of moving that sets them apart from other amphibians.

The oldest fossil "proto-frog" appeared in the early Triassic of Madagascar, showing us what early versions of frogs might have looked like. By studying these fossils, scientists can learn about how frogs and toads have changed over millions of years.

Even though the first fossils are from the Triassic period, molecular clock dating suggests that the origins of Salientia might go back even further—to the Permian, about 265 million years ago. This means that the ancestors of today’s frogs and toads might have been living on Earth long before the first dinosaurs appeared.

Characteristics

Very few fossils of early salientians have been found, making it hard to define their characteristics and relationships. Some features, like the arrangement of bones in their chests and spines, give clues, but they are not always reliable. Early proto-frogs evolved from ancestors called temnospondyls, and their body structures, such as the pelvis and hind limbs, were likely better suited for swimming than jumping. These early frogs probably developed their main features during the time of the Mesozoic or early Tertiary periods. Today, families like Alytidae, Pipidae, and Pelobatidae live in special areas, while harlequin frogs are found in Central and South America, and groups like Ranidae and Bufonidae likely spread out 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 to each other. Some studies suggest that salamanders and caecilians are more closely related to each other than to frogs. These groups likely began to separate from each other in the ancient past, before the continents we know today had drifted 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. While it looked somewhat like a modern frog, it had differences such as more body segments and separate leg bones, meaning it probably couldn’t jump as well as frogs do today.

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. However, scientists believe that these animals might have first appeared even earlier, perhaps as far back as the Permian period, around 265 million years ago.