Were these giant, crocodile-like amphibians the true ancestors of every modern frog and salamander?

Nature · Published 3 October 2026 Swipe more like this →

In short: For over 200 million years, temnospondyls dominated the Earth, evolving from small, salamander-like creatures into massive, armored predators. While they vanished by the Late Cretaceous, their legacy remains a subject of intense scientific debate: did they leave behind the modern amphibians we see today, or did they die out entirely?

Temnospondyli, meaning 'cut vertebrae,' refers to a diverse order of ancient tetrapods that flourished from the Carboniferous to the Early Cretaceous. Unlike modern soft-bodied lissamphibians, many temnospondyls were heavily armored with scales and bony plates called osteoderms. Their evolutionary history spans roughly 210 million years, during which they successfully colonized freshwater, terrestrial, and coastal marine environments across every continent.

The group is defined by a unique vertebral structure where each segment is divided into an intercentrum and paired pleurocentra. This anatomy varied significantly; some species, like the rhachitomous types, possessed strong backbones and limbs suited for terrestrial life, while others, known as stereospondyls, evolved weaker backbones and spent their lives in water. These aquatic forms could reach massive sizes, with skulls exceeding one meter in length, far surpassing the largest living amphibian, Andrias, which measures about 1.8 meters in total body length.

Scientific consensus on their lineage remains elusive. While some researchers argue that temnospondyls are the ancestors of modern frogs, salamanders, and caecilians, others suggest these groups evolved from a different lineage called lepospondyls. A prominent hypothesis posits that a specific subgroup, the amphibamiforms, represents the closest relatives to modern amphibians, citing shared characteristics in their teeth, skulls, and hearing structures. However, because soft tissue preservation is rare, many aspects of their biology—such as the function of their characteristic honeycomb-like skull ornamentation—remain speculative.

The classification of these animals has shifted dramatically since they were first identified in the early 19th century. Early paleontologists like Richard Owen initially misidentified them as reptiles, naming them 'labyrinthodonts' for their highly folded teeth. It was not until 1888 that Karl Alfred von Zittel formally established the name Temnospondyli. Today, the group is recognized as a complex clade whose relationship to the tetrapod crown depends entirely on whether they are indeed the ancestors of the lissamphibians that survive today.

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