Genyodectes( "jaw bite", from theGreekwordsgenys( "jaw" ) anddektes( "bite" )) is agenusofceratosauriantheropoddinosaur from the LowerCretaceous(Aptian) ofSouth America.Theholotypematerial (MLP 26–39, Museo de La Plata,La Plata,Argentina) was collected from theCerro Barcino Formation,Cañadón Grande, Departamento Paso de Indios in theChubut ProvinceofArgentinaand consists of an incomplete snout, including thepremaxillae,portions of bothmaxillas,the right and leftdentary,manyteeth,a fragment of the leftsplenial,and parts of the supradentaries. These elements are generally poorly preserved and some are in articulation. The premaxilla ofGenyodectespossesses relatively large and protruding teeth, similar to those ofCeratosaurus.The specific name,serus,means "late". In 2016 it was estimated to be 6.25 meters (20.5 ft) in length and 790 kg (1,740 lb) in weight.[1]
| Genyodectes Temporal range:Early Cretaceous,
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| Genyodectesholotype | |
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| Illustration from original description | |
Scientific classification
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Family: | †Ceratosauridae |
| Genus: | †Genyodectes Woodward 1901 |
| Species: | †G. serus
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| Binomial name | |
| †Genyodectes serus Woodward, 1901
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Taxonomy and phylogeny
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Thetaxonhas long been considered anomen dubium,owing to its fragmentary nature and some doubt as to its precise geographic andstratigraphicorigins (see Tykoski et Rowe, 2004, p. 50).[2]However, a recent redescription of the type material by Rauhut (2004) has shed some light on these questions and seems to establish thetaxonomicvalidity ofGenyodectes serus,the only species referred to the genus.[3]
EnglishpaleontologistSir Arthur S. Woodward describedGenyodectesin 1901,[4]and, afterLoncosaurus(Ameghino,1899;nomen dubium),[5]it is the second non-aviandinosaur described from the South Americancontinent,and it remained the most completely known South American theropod until the 1970s.[3]
Over the last decade, the holotype has been variously referred to as amegalosaurid,atyrannosaurid,Theropodaincertae sedis,and a possibleabelisaurid(perhaps even asenior synonymofAbelisaurus). However, the recent removal of the holotype from the "artificial matrix" in which it had long been displayed has permitted a reevaluation of the specimen. Rauhut (2004, p. 900) concluded that the specimen lacks important abelisaurid and tyrannosauridsynapomorphies,but found many neoceratosaurian traits.[3]This would seem to implyGenyodecteswas closer toCeratosaurusthan the more derived abelisaurs (that also descended from animals likeCeratosaurus). Also, by studying historical records and preservation of the bones, Rauhut (2004, p. 894) concluded that the specimen was likely collected from the Cerro Castaño Member of theCerro Barcino Formation(Aptian-Albian).[3]
Diagnosis
editRauhut diagnosesGenyodectes serusas follows:[6]"Differs from all theropods with the possible exception ofCeratosaurusin that the premaxillary teeth are arranged in an overlappingen-echelonpattern and the longest maxillary tooth crowns are longer apicobasally than the minimal dorsoventral depth of the mandible. Differs fromCeratosaurusin the presence of four, as opposed to three, premaxillary teeth. "[3]
References
edit- ^Molina-Pérez & Larramendi (2016).Récords y curiosidades de los dinosaurios Terópodos y otros dinosauromorfos.Barcelona, Spain: Larousse. p. 255.
- ^Tykoski, R.S., and Rowe, T. (2004). Ceratosauria. In: Weishampel, D.B., Dodson, P., and Osmólska, H. (Eds.).The Dinosauria(2nd edition). University of California Press:Berkeley.ISBN0-520-24209-2.
- ^abcdeRauhut, O.W.M. (2004). Provenance and anatomy ofGenyodectes serus,a large-toothed ceratosaur (Dinosauria: Theropoda) from Patagonia.Journal of Vertebrate Paleontology24(4):894-902.
- ^Woodward A. S. 1901. On some extinct reptiles from Patagonia, of the generaMeiolania,Dinilysia,andGenyodectes.Proceedings of the Zoological Society of London1901:169-184.
- ^Ameghino, F.(1899). Nota preliminar sobre elLoncosaurus argentinus,un representante de la familia de los Megalosauridae en la Republica Argentina.Anales de la Sociedad Cientifica Argentina47:61-62.
- ^Rauhut, O.W.M. (2004) Provenance and anatomy ofGenyodectes serus,a large-toothed ceratosaur (Dinosauria: Theropoda) from Patagonia. Journal of Vertebrate Paleontology 24(4):895-895