| Euthecodon Fossil range: Early Miocene - Early Pleistocene, 23.03-.781 Ma | |
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Crocodylinae |
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Genus |
Euthecodon Fortau, 1920 |
Euthecodon is an extinct genus of longirostrine crocodyline crocodilian. It was common throughout much of Africa during the Neogene, with fossils being especially common in Kenya. It existed from the Early Miocene to the Early Pleistocene.
Description[]
Euthecodon was large for a crocodilian. One specimen, LT 26306, found from the Turkana Basin, was estimated by skull length to have been around 10m long[1]. It had a narrow rostrum that was unusually elongate with deeply scalloped dorsal margins. The skull table, however, was proportionally small and is almost square in shape. The jaws were lined with slender, similarly sized and shaped teeth (isodontic). Unlike nearly all other crocodilians, Euthecodon possessed only four premaxillary teeth. Because they are sharp and bicarinate, they are believed to have been an adaptation for a piscivorous feeding habit or a diet that included fish.
Discovery and species[]
Collected material now known to be from Euthecodon was initially placed in the genus Tomistoma, of which the modern false gharial is a member. These specimens were described from the Pliocene Omo Group in Ethiopia [2]. The genus Euthecodon was first named in 1920 on the basis of material found from Wadi Natrun, Egypt. This material was believed to have belonged to the same species as the specimens from Ethiopia, yet it appeared to be distinct from the genus Tomistoma. As a result, the material from Ethiopia was reassigned to the new genus along with the material from Egypt, with the species being named E. nitriae[3].
A new species, named E. brumpti, was found from Lothagam, Kenya and can be distinguished from E. nitriae by skull and rostral proportions as well as tooth count[4][5][6]. E. brumpti is the most common fossil crocodilian found from the Turkana Basin, along with Rimasuchus lloydi. A complete articulated skull and mandible referrable to E. brumpti was found in situ from the Kaiyumung Member of the Nachukui Formation in Lothagam in 1992[7].
A shorter snouted species named E. arambourgi has been found from early Miocene deposits in Gebel Zelten, Lybia[8][9][10]. Classification of specimens from several localities across Africa are indeterminant at the species level, with material being found from the Sahabi Formation in Lybia of early Pliocene age[11], the Victoria Basin strata of Rusinga Island of early Miocene age[12], early Miocene deposits in Ombo, Kenya[13], and possibly the Albertine Rift sediments of the Congo of early Miocene age[14][15].
Phylogeny[]
Euthecodon was originally considered a tomistomine crocodilian. It has even been suggested to be a direct offshoot of Eogavialis[16][17]. However, it is now thought to be a crocodylid, having been allied with Rimasuchus, Osteolaemus, and Voay in the past[18][19].
References[]
- ^ Storrs, G. W. (2003). Late Miocene-Early Pliocene crocodilian fauna of Lothagam, southwest Turkana Basin, Kenya. In: Lothagam: The Dawn of Humanity in Eastern Africa pp. 137–159. New York. Columbia University Press. ISBN 0231118708.
- ^ Joleaud, L. (1920). Sur la présence d'un Gavialide du genre Tomistoma dans le Pliocène d'eau douce de l'Ethiopie. Comptes Rendus de l'Académie des Sciences 70:816-818.
- ^ Forteau, R., ed. (1920). Contribution à l'étude de vertébrés Miocènes de l'Egypt. Cairo. Government Press.
- ^ Ginsburg, L. E. and Buffetaut, E. (1978). Euthecodon arambourgi n. sp. et l'évoluion du genera Euthecodon, crocodilien du Néogène d'Afrique. Géologie Méditerranéenne 5:291-302.
- ^ Kälin, J. (1955). Crocodilia. In: J. Piveteau, ed., Traité de paléontologie 5:695-784. Paris: Masson.
- ^ Steel, R. (1973). Crocodylia. In: O. Kuhn, ed., Handbuch der Paläoherpetologie 16:1-116. Stuttgart. Fischer.
- ^ Leakey, M. G. and Harris, J. M. (2003). "Introduction". Lothagam: The Dawn of Humanity in Eastern Africa. Columbia University Press. New York. p. 6. ISBN 0231118708
- ^ Arambourg, C. and Magnier, P. (1961). Gisement de vértébres dans le bassin tertiare de Syrte (Lybie). Comptes Rendus de l'Académie des Sciences 252:1181-1183.
- ^ Buffetaut, E. (1985). Zoogeographical history of African crocodilians since the Triassic. In: Karl L. Schuchmann, ed., Proceedings of the International Symposium on African Vertebrates: Systematics, Phylogeny and Evolutionary Ecology. pp. 453-469. Bonn. Zoologisches Forschunginstitut und Museum Alexander Koening.
- ^ Ginsburg, L. and Buffetaut, E. (1978). Euthecodon arambourgi n. sp. et l'évolution du genre Euthecodon, crocodilien du Néogène d'Afrique. Géologie Méditerranéenne 5:291-302.
- ^ Hecht, M. K. (1987). Fossil snakes and crocodilians from the Sahabi Formation of Lybia. In: N. T. Boaz, A. El-Arnauti, A. W. Gaziry, J. de Heinzelin, and D. D. Boaz, eds., Neogene Paleontology and Geology of Sahabi. pp. 101-106. New York. Liss.
- ^ Tchernov, E. and Van Couvering, J. (1978). New crocodiles from the Early Miocene of Kenya. Palaeontology 21:857-867.
- ^ Buffetaut, E. (1979). Présence du crocodilien Euthecodon dans le Miocène inférieur d'Ombo (golfe de Kavirondo, Kenya). Bulletin de la Société Géologique de France 21:321-322
- ^ Aoki, R. (1992). Fossil crocodilians from the Late Tertiary strata in the Sinda Basin, eastern Zaire. African Study Monographs, Supplementary issue 17:67-85.
- ^ Pickford, M. (1994). Late Cenozoic crocodiles (Reptilia:Crocodylidae) from the Western Rift, Uganda. In: B. Senut and M. Pickford, eds., Geology and Paleobiology of the Albertine Rift Valley, Uganda-Zaire. Paleobiology/Paléobiologie 2(29):137-155. Orléans. Centre International pour la Formation et les Echanges Géologiques.
- ^ Tchernov, E. (1976). Crocodylidae from the Pliocene/Pleistocene formations of the Rudolf Basin. In: Y. Coppens, F. C. Howell, G. L. Isaac and R. E. Leakey, eds., Earliest Man and Environments in the Lake Rudolf Basin: Stratigraphy, Paleoecology, and Evolution, pp. 370-378. Chicago. University of Chicago Press.
- ^ Tchernov, E. (1986). Evolution of the Crocodiles in East and North Africa. Cahiers de Paléontologie. Paris. Centre National pour la Formation et les Echanges Géologiques.
- ^ Brochu, C. (1997). Morphology, fossils, divergence timing, and the phylogenetic relationships of Gavialis. Systematic Biology 46:479-522.
- ^ Brochu, C. and Storrs, G. W. (1995). The giant dwarf crocodile: A reappraisal of "Crocodylus" robustus from the Quaternary of Madagascar. In: B. D. Patterson, S. M. Goodman, and J. L. Sedlock, eds., Environmental Change in Madagascar. pp. 6. Chicago. Field Museum.
External links[]
- Euthecodon in the Paleobiology Database