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Unknown, possibly Anura


Possibly Archaeobatrachia






T. massinoti



Time range

230 mya

Triadobatrachus, meaning "third frog", is an extinct amphibian with a strong resemblance to the tailed toad of today. It is the oldest frog known to science, and an excellent example of a transitional fossil. It lived during the Early Triassic, in what is now Madagascar.


It was first discovered on 1937, when Adrien Massinot, near the village of Betsieka in northern Madagascar, found an almost complete skeleton. The animal must have fossilized soon after its death, because all bones lay in their natural position. Only the anterior part of the skull and the ends of the limbs were missing.

Although it was found in marine deposits, the general structure of Triadobatrachus shows that it may have lived for part of the time on land and breathed air. Its proximity to the mainland is further borne out by the remains of terrestrial plants found together with it.


Triadobatrachus has been placed in its own family, the Protobatrachidae. Exactly how it is related to modern frogs has long been a matter of debate, especially considering the fact that the holotype specimen possessed a shortened appendage above the cloaca. This appears to be similar to that of the modern tailed toad. It seems likely that Triadobatrachus was a toad, as they are considered to be older than frogs, as modern examples are almost more reptilian than amphibian in terms of external appearence. It is probable that the first examples of toads, such as Triadobatrachus, looked similar to modern true frogs.


Triadobatrachus was 10 centimetres (3.9 in) long, and still retained many primitive characteristics, such as possessing fourteen vertebrae, where modern frogs have only four to nine. Triadobatrachus was fairly elongated for a frog, similar in looks to a slender harlequin frog (Atelopus spp.), or a tailess salamander. It probably swam by kicking its hind legs, although it could not jump, as all modern frogs can. Its skull resembled that of modern frogs, consisting of a latticework of thin bones separated by large openings. As evidenced by its large ear openings, Triadobatrachus possessed good hearing.

Perhaps the most curious feature of Triadobatrachus is the short tail-like appendage above the cloacal area. This is remarkably similar to the tailed toad's "tail". However, the two are actually very different. The "tail" in the tailed toad is not a true part of the backbone, but rather an extension of the penis. Triadobatrachus, however, had six to eight vertebrae in its short tail. Perhaps the tail was simply being lost, as the basal amphibians that were the ancestors of all amphibians evolved into frogs. Alternatively, the tail may have been used as a rudder in the water, although it seems too short to serve such a purpose.