The First Leap

The ‘missing link’ between fish and salamanders

375 million years ago, a strange being was swimming through the primordial ocean. It had fins, scales and gills like a fish, but it also had a flattened body with eyes placed on top of its head like a salamander. It had ribs for support when it occasionally crawled onto land.

The fishapod, discovered in 2006, is the long sought-after missing link in the evolution from fish to the first amphibians. It’s the first ancestor of all terrestrial vertebrates, the tetrapods.

The first amphibian species in history


About 370 million years ago, in the Devonian Period, the Ichthyostega developed. It was no longer a fish. The four-legged salamander-like animal was one of the first terrestrial vertebrates.

It was capable of spending some time out of water. Its feet were still fin-like but attached to legs and fairly inflexible. These prehistoric animals couldn’t walk yet. Instead, they used their limbs as crutches to pull their bodies through the mud.

Half frog, half salamander: the ‘frogamander’ Gerobatrachus

290 million years ago, a number of amphibian species had already made a home for themselves on land. They moved further and further inland and conquered new terrestrial habitats. But the salamander anatomy wasn’t ideal for every mode of living. They began to diverge into two major groups: the caudates (salamanders) and the anurans (frogs).

The frogamander displays features common to both frogs and salamanders, making it their last common ancestor.

Triadobatrachus massinoti, the world’s first frog


About 250 million years ago, long before the arrival of the dinosaurs, a ten-centimetre-long amphibian with a flat, compact body emerged on the supercontinent Pangaea. Unlike its salamander-like ancestors, it only had a small tail supported by six vertebrae.

Triadobatrachus is regarded as the world’s first frog. It was already a strong swimmer with its powerful legs. The predisposition of their descendants’ jumping legs is clearly obvious!

A representative of the past

Tailed frogs are one of the world’s oldest frog species. Their nine vertebrae are evidence of their evolutionary relationship with salamanders – modern frogs have five to eight vertebrae, only. The males’ ‘tail stump’, on the other hand, is an extension of the cloaca and is used for procreation, because they live in fast-flowing streams. Their sperm would merely be swept away if secreted into water like other frogs do.

Tailed frogs are the only frogs to have developed this kind of internal fertilisation.