Genyodectes

Genyodectes
Snout fragment ( holotype specimen) of Genyodectes serus
Temporal occurrence
Aptium ( Lower Cretaceous )
126.3 to 112.9 million years
Locations
Chubut , Argentina ( Cerro Barcino Formation )
Systematics
Dinosaur (dinosauria) Lizard dinosaur (Saurischia) Theropoda Ceratosauria Genyodectes
Scientific name
Genyodectes
Woodward , 1901
Art
Genyodectes serus

Genyodectes is a genus theropod dinosaur from the group of Ceratosauria . So far only an incomplete snout is known, which was discovered in the Argentine province of Chubut and is around 112 million years old ( Aptian , Lower Cretaceous ). The only species is Genyodectes serus . Genyodectes wasscientifically describedas early as 1901 by Arthur Smith Woodward ; thus it is the first undoubted non-avian theropod to be described from South America. The genus is particularly characterized by the relatively very long tooth crowns of the upper jaw.

Research history

The snout fragment ( holotype , copy number MLP 26-39, Museo de La Plata) consists of the intermaxillary bone (premaxillary), parts of both maxillaries , the right and left dentals , teeth, a fragment of the left splenial and parts of the supradental. The find was given to the geologist Santiago Roth during one of his expeditions to Cañadón Grande in the Argentine province of Chubut at the end of the 19th century by a local gaucho . Later , the English paleontologist Sir Arthur Smith Woodward described the fossil under the name Genyodectes serus ( Greek genys - "jaw, chin", dektes - "biter"). The exact location and therefore the exact geological age of the genus remained uncertain. For a long time it was assumed that these remains originate from the Upper Cretaceous , and in more recent times Genyodectes has often been associated with the Abelisaurids . However, a more recent study of the material by Oliver Rauhut (2004) suggests that Genyodectes comes from the Cerro-Castaño-Member, the lower layer member of the Cerro-Barcino Formation , and thus falls into the Lower Cretaceous (Aptian). In addition, Rauhut suspects that Genyodectes is related to the Upper Jurassic genus Ceratosaurus , so it belonged to the Ceratosauridae .

features

Genyodectes has long been listed as the noun dubium (dubious name) because of the very fragmentary remains and the unclear stratigraphic origin . However, the revision of the genre by Oliver Rauhut tries to restore the genre's validity. According to Rauhut, Genyodectes can be distinguished from other genera by its tightly packed, overlapping teeth in the intermaxillary bone and the strongly flattened teeth of the maxillary. A common feature with Ceratosaurus were the greatly elongated crowns of the upper jaw, the length of which exceeded the smallest height of the lower jaw; the longest tooth crown is reconstructed with a length of 9.5 cm. In contrast to Ceratosaurus , Genyodectes had 4 instead of 3 teeth in the intermaxillary bone.

supporting documents

1. ^ Arthur Smith Woodward : On some Extinct Reptiles from Patagonia, of the Genera Meiolania, Dinilysia, and Genyodectes. In: Proceedings of the Zoological Society of London. Vol. 70, No. 2, 1901, ISSN  0370-2774 , pp. 169-184, digitized version (PDF; 3.22 MB) .
2. ↑ ^{a b c} Oliver WM Rauhut : Provenance and anatomy of Genyodectes serus, a large-toothed ceratosaur (Dinosauria: Theropoda) from Patagonia. In: Journal of Vertebrate Paleontology. Vol. 24, No. 4, 2004, ISSN  0272-4634 , pp. 894-902, doi : 10.1671 / 0272-4634 (2004) 024 [0894: PAAOGS] 2.0.CO; 2 .
3. ↑ Ben Creisler: Dinosauria Translation and Pronunciation Guide. Archived from the original on July 20, 2011 ; Retrieved December 3, 2013 . 
4. ↑ Ronald S. Tykoski, Timothy Rowe : Ceratosauria. In: David B. Weishampel , Peter Dodson , Halszka Osmólska (eds.): The Dinosauria . 2nd edition. University of California Press, Berkeley CA et al. 2004, ISBN 0-520-24209-2 , pp. 47-70.