Triadobatrachus massinoti (lat.) Is an extinct amphibian from the order Salientia , the only known representative of the genus Triadobatrachus . Its only copy was discovered in Madagascar and dates from the Lower Triassic [2] . The estimated length of the Triadobatrachus is 10 cm, the structure of its skull resembles modern frogs , and the number of vertebrae and the structure of the limbs correspond to more primitive forms of amphibians. Jumping was not characteristic of Triadobatrachus , but its structure contained some features that may have served as preadaptations to the evolution of jumping. Triadobatrachus is considered as a transitional link in the evolution of tailless [3] .
| † Triadobatrachus massinoti | |||||||||||||||||||||||||||||||||||||||||
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Triadobatrachus massinoti | |||||||||||||||||||||||||||||||||||||||||
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| Geochronology Lower Triassic 251.9-247.2 Ma
◄ Nowadays◄ Cretaceous-Paleogene extinction◄ Triassic extinction◄ Mass Permian Extinction◄ Devonian extinction◄ Ordovician-Silurian extinction◄ Cambrian explosion | |||||||||||||||||||||||||||||||||||||||||
Study History
The only known instance of Triadobatrachus massinoti MNHN no MAE 126 was discovered by amateur paleontologist A. Massino (Adrien Massinot) near the village of Betsieka in northern Madagascar. The found specimen is perfectly preserved, there is an almost complete skeleton, the bones of which are located in a natural order. Of the missing bones, only the front of the skull and the ends of the limbs can be noted. Also, the outline of the soft parts of the animal was preserved on the print [4] . In 1936, the fossil was described by the French paleontologist Jean Piveteau (to whom Massino handed over his find) under the name Protobatrahcus massinoti [5] [6] . A much more detailed description was made in 1989 [7] .
Today, the only copy of the Triadobatrachus massinoti is kept in the National Museum of Natural History in Paris [4] .
Description
The length of the Triadobatrachus was about 10 cm. Triadobatrachus had a wide skull with large eye sockets, which resembled a frog skull , but this fossil also had some characteristics that distinguished it from modern tailless ones. So, his body was more elongated, and there were more pre-sacral vertebrae than modern frogs (he had 14 vertebrae , while the number of vertebrae in modern tailless does not exceed 9). There was a short tail , the vertebrae of which did not grow together in growth . The ileum of the pelvis was directed forward. The radius bones were not fused with the ulnar , and the small tibia with the large . The dimensions of the hind limbs of Triadobatrachus are proportional to the size of the body (while the hind limbs of modern tailless are disproportionately large) [8] . Based on the foregoing, it can be assumed that Triadobatrachus was not able to jump efficiently [9] , but could swim using hind limbs like modern frogs [10] .
Systematics
Researchers who describe the Triadobatrachus concluded that it is one of the links in the evolution of tailless, that is, it can be considered the ancestor of modern tailless. More recent studies indicate that Triadobatrachus is more likely to be a sister to the tailless clade , and not an ancestor of tailless [11] . This hypothesis combines Triadobatrachus and tailless in the Salientia group. Sometimes Triadobatrachus is placed in the suborder Proanura [12] .
Place of the Triadobatrachus in the evolution of tailless
Triadobatrachus is considered a transitional link between primitive amphibians and more evolutionally advanced tailless. The structure of the skull of Triadobatrachus is the closest to modern tailless, while its limb belts are at the level of earlier amphibians (such as Eoscopus and Doleserpeton , which are considered closest to the branch of tailless sister taxa) [13] . These properties of Triadobatrachus allowed researchers to hypothesize that tailless evolution was dictated primarily by changes in the cranial region, and adaptation to jumping movements is secondary to them. At the same time, some anatomical features of the Triadobatrachus , such as, for example, the forward pelvic ilium and the shorter (compared to the early amphibians) spine , are preadaptations to the evolution of jumping movements [14] .
Notes
- ↑ 1 2 † Triadobatrachus massinoti (English) information on the Fossilworks website. (Retrieved September 27, 2016) .
- ↑ Triadobatrachus massinoti (English) . Paleobiology Database Classic . (Retrieved September 27, 2016) .
- ↑ Rocek, 2000 , p. 1283-1294.
- ↑ 1 2 Rocek, 2000 , p. 1283.
- ↑ Piveteau, J. Une forme ancestrale des amphibiens anoures dans le Trias inférieur de Madagascar (Fr.) // Comptes Rendus hebdomadaires des séances de l'Académie des Sciences: magazine. - 1936. - Vol. 202 . - P. 1607-1608 .
- ↑ Piveteau, J. Origine et évolution morphologique des amphibiens anoures (French) // Comptes Rendus hebdomadaires des séances de l'Académie des Sciences: magazine. - 1936. - Vol. 203 . - P. 1084-1086 .
- ↑ Rage, JC; Roček, Z. Redescription of Triadobatrachus massinoti (Piveteau, 1936) an anuran amphibian from the Early Triassic (English) // Palaeontographica Abteilung A, Palaeozoologie-Stratigraphie: journal. - 1989. - Vol. 206 . - P. 1-16 .
- ↑ Holman, 2003 , p. 29.
- ↑ Cannatella, David Triadobatrachus massinoti . Tree of Life (1995). Date of treatment February 12, 2015. Archived on August 20, 2012.
- ↑ The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals / Palmer, D. - London: Marshall Editions, 1999 .-- P. 56. - ISBN 1-84028-152-9 .
- ↑ Alexander Pyron, R. Divergence Time Estimation Using Fossils as Terminal Taxa and the Origins of Lissamphibia (English) // Syst Biol: journal. - 2011. - Vol. 60 , no. 4 . - P. 466-481 . - DOI : 10.1093 / sysbio / syr047 .
- ↑ Rocek, 2000 , p. 1284.
- ↑ Rocek, 2000 , p. 1292.
- ↑ Rocek, 2000 , p. 1293.
Literature
- Grzimek, B. Grzimek's Animal Life Encyclopedia. - 2nd edition. - Farmington Hills: Gale Group, 2003. - Vol. 6, Amphibians. - P. 3—321. - ISBN 0-7876-5362-4 .
- Holman, AJ North American anuran genera of uncertain family relationships // Fossil Frogs and Toads of North America. - Bloomington, IN, USA: Indiana University Press, 2003 .-- 264 p. - ISBN 9780253000569 .
- Rocek, Z.,. Proanuran stages ( Triadobatrachus , Czatkobatrachus ). // Amphibian Biology / Carroll, RL and Heatwole, H. (eds). - Chipping Norton, Australia: Surrey Beatty & Sons, 2000. - Vol. 4 Paleontology. - P. 1283-1294. - ISBN 0949324876 .