Genyodectes: Difference between revisions
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== Taxonomy and phylogeny == |
== Taxonomy and phylogeny == |
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[[File:Genyodectes.jpg|thumb|left|Illustration of the type specimen from the original description]] |
[[File:Genyodectes.jpg|thumb|left|Illustration of the type specimen from the original description]] |
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[[File:Genyodectes restoration.png|thumb|left|Restoration of ''Genyodectes'' hunting an early mammal]] |
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[[File:Genyodectes known material.png|thumb|right|Known material of ''Genyodectes'']] |
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[[File:Genyodectes size.png|left|thumb|Size of ''Genyodectes'' compared to a human]] |
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The [[taxon]] has long been considered a [[nomen dubium]], owing to its fragmentary nature and some doubt as to its precise geographic and [[stratigraphic]] origins (see Tykoski et Rowe, 2004, p. 50).<ref name=TR04>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. {{ISBN|0-520-24209-2}}.</ref> However, a recent redescription of the type material by Rauhut (2004) has shed some light on these questions and seems to establish the [[Taxonomy (biology)|taxonomic]] validity of ''Genyodectes serus'', the only species referred to the genus.<ref name=OR04>Rauhut, O.W.M. (2004). Provenance and anatomy of ''Genyodectes serus'', a large-toothed ceratosaur (Dinosauria: Theropoda) from Patagonia. ''Journal of Vertebrate Paleontology'' '''24'''(4):894-902.</ref> English [[paleontologist]] Sir Arthur S. Woodward described ''Genyodectes'' in 1901,<ref name=ASW01>Woodward A. S. 1901. On some extinct reptiles from Patagonia, of the genera ''[[Meiolania]]'', ''[[Dinilysia]]'', and ''Genyodectes''. ''Proceedings of the Zoological Society of London'' 1901:169-184.</ref> and, after ''[[Loncosaurus]]'' ([[Florentino Ameghino|Ameghino]], 1899; ''nomen dubium''),<ref name=FA99>[[Ameghino, F.]] (1899). Nota preliminar sobre el ''[[Loncosaurus argentinus]]'', un representante de la familia de los Megalosauridae en la Republica Argentina. ''Anales de la Sociedad Cientifica Argentina'' '''47''':61-62.</ref> it is the second non-[[bird|avian]] dinosaur described from the South American [[continent]], and it remained the most completely known South American theropod until the 1970s. Over the last decade, the holotype has been variously referred to as a [[megalosaurid]], a [[tyrannosaurid]], Theropoda ''[[incertae sedis]]'', and a possible [[abelisaurid]] (perhaps even a [[senior synonym]] of ''[[Abelisaurus]]''). 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 tyrannosaurid [[synapomorphies]], but found many neoceratosaurian traits.<ref name=OR04/> This would seem to imply ''Genyodectes'' was closer to ''Ceratosaurus'' than the more derived abelisaurs (that also descended from animals like ''Ceratosaurus''). 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 the [[Cerro Barcino Formation]] ([[Aptian]]-[[Albian]]).<ref name=OR04/> |
The [[taxon]] has long been considered a [[nomen dubium]], owing to its fragmentary nature and some doubt as to its precise geographic and [[stratigraphic]] origins (see Tykoski et Rowe, 2004, p. 50).<ref name=TR04>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. {{ISBN|0-520-24209-2}}.</ref> However, a recent redescription of the type material by Rauhut (2004) has shed some light on these questions and seems to establish the [[Taxonomy (biology)|taxonomic]] validity of ''Genyodectes serus'', the only species referred to the genus.<ref name=OR04>Rauhut, O.W.M. (2004). Provenance and anatomy of ''Genyodectes serus'', a large-toothed ceratosaur (Dinosauria: Theropoda) from Patagonia. ''Journal of Vertebrate Paleontology'' '''24'''(4):894-902.</ref> English [[paleontologist]] Sir Arthur S. Woodward described ''Genyodectes'' in 1901,<ref name=ASW01>Woodward A. S. 1901. On some extinct reptiles from Patagonia, of the genera ''[[Meiolania]]'', ''[[Dinilysia]]'', and ''Genyodectes''. ''Proceedings of the Zoological Society of London'' 1901:169-184.</ref> and, after ''[[Loncosaurus]]'' ([[Florentino Ameghino|Ameghino]], 1899; ''nomen dubium''),<ref name=FA99>[[Ameghino, F.]] (1899). Nota preliminar sobre el ''[[Loncosaurus argentinus]]'', un representante de la familia de los Megalosauridae en la Republica Argentina. ''Anales de la Sociedad Cientifica Argentina'' '''47''':61-62.</ref> it is the second non-[[bird|avian]] dinosaur described from the South American [[continent]], and it remained the most completely known South American theropod until the 1970s. Over the last decade, the holotype has been variously referred to as a [[megalosaurid]], a [[tyrannosaurid]], Theropoda ''[[incertae sedis]]'', and a possible [[abelisaurid]] (perhaps even a [[senior synonym]] of ''[[Abelisaurus]]''). 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 tyrannosaurid [[synapomorphies]], but found many neoceratosaurian traits.<ref name=OR04/> This would seem to imply ''Genyodectes'' was closer to ''Ceratosaurus'' than the more derived abelisaurs (that also descended from animals like ''Ceratosaurus''). 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 the [[Cerro Barcino Formation]] ([[Aptian]]-[[Albian]]).<ref name=OR04/> |
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Revision as of 02:02, 28 December 2018
| Genyodectes Temporal range: Early Cretaceous,
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| Genyodectes holotype | |
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 | |
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Genyodectes ("jaw bite", from the Greek words genys ("jaw") and dektes ("bite")) is a genus of ceratosaurian theropod dinosaur from the Lower Cretaceous (Aptian) of South America. The holotype material (MLP 26-39, Museo de La Plata, La Plata, Argentina) was collected from the Cerro Barcino Formation, Cañadón Grande, Departamento Paso de Indios in the Chubut Province of Argentina and consists of an incomplete snout, including the premaxillae, portions of both maxillas, the right and left dentary, many teeth, a fragment of the left splenial, and parts of the supradentaries. These elements are generally poorly preserved and some are in articulation. The premaxilla of Genyodectes possesses relatively large and protruding teeth, similar to those of Ceratosaurus. The specific name, serus, means "late".
Taxonomy and phylogeny
The taxon has long been considered a nomen dubium, owing to its fragmentary nature and some doubt as to its precise geographic and stratigraphic origins (see Tykoski et Rowe, 2004, p. 50).[1] However, a recent redescription of the type material by Rauhut (2004) has shed some light on these questions and seems to establish the taxonomic validity of Genyodectes serus, the only species referred to the genus.[2] English paleontologist Sir Arthur S. Woodward described Genyodectes in 1901,[3] and, after Loncosaurus (Ameghino, 1899; nomen dubium),[4] it is the second non-avian dinosaur described from the South American continent, and it remained the most completely known South American theropod until the 1970s. Over the last decade, the holotype has been variously referred to as a megalosaurid, a tyrannosaurid, Theropoda incertae sedis, and a possible abelisaurid (perhaps even a senior synonym of Abelisaurus). 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 tyrannosaurid synapomorphies, but found many neoceratosaurian traits.[2] This would seem to imply Genyodectes was closer to Ceratosaurus than the more derived abelisaurs (that also descended from animals like Ceratosaurus). 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 the Cerro Barcino Formation (Aptian-Albian).[2]
Diagnosis
Rauhut (2004, p. 895-896) diagnoses Genyodectes serus as follows: "Differs from all theropods with the possible exception of Ceratosaurus in that the premaxillary teeth are arranged in an overlapping en-echelon pattern and the longest maxillary tooth crowns are longer apicobasally than the minimal dorsoventral depth of the mandible. Differs from Ceratosaurus in the presence of four, as opposed to three, premaxillary teeth."[2]
See also
References
- ^ 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. ISBN 0-520-24209-2.
- ^ a b c d Rauhut, O.W.M. (2004). Provenance and anatomy of Genyodectes serus, a large-toothed ceratosaur (Dinosauria: Theropoda) from Patagonia. Journal of Vertebrate Paleontology 24(4):894-902.
- ^ Woodward A. S. 1901. On some extinct reptiles from Patagonia, of the genera Meiolania, Dinilysia, and Genyodectes. Proceedings of the Zoological Society of London 1901:169-184.
- ^ Ameghino, F. (1899). Nota preliminar sobre el Loncosaurus argentinus, un representante de la familia de los Megalosauridae en la Republica Argentina. Anales de la Sociedad Cientifica Argentina 47:61-62.
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