Talenkauen

Talenkauen (meaning "small skull" in Aonikenk, referring to the proportionally small skull) is a genus of basal iguanodont dinosaur from the Cenomanian-age[1] Late Cretaceous Cerro Fortaleza Formation, formerly known as the Pari Aike Formation of Patagonian Lake Viedma in the Austral Basin of Santa Cruz, Argentina. It is based on MPM-10001, a partial articulated skeleton missing the rear part of the skull, the tail, and the hands. Its most unusual feature is the presence of several thin mineralized plates along the sides of the ribs.[2]

Talenkauen
Temporal range: Cenomanian
~96.2 Ma
Talenkauen
Skeleton
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Ornithischia
Clade: Neornithischia
Clade: Elasmaria
Genus: Talenkauen
Novas et al. 2004
Species:
T. santacrucensis
Binomial name
Talenkauen santacrucensis
Novas et al. 2004

Description

Talenkauen fossil
Alternate view of skeleton

Talenkauen was rather like Dryosaurus in shape and build, but with a proportionally longer neck. The full length of the body is estimated at no more than 4 meters (13 feet). Unlike more derived iguanodontians, it still had teeth in the tip of the beak (premaxillary teeth), and a first toe. More derived iguanodonts lose this toe, retaining only the three middle toes. The humerus has reduced areas for muscle attachment, a featured shared with other South American ornithopods like Notohypsilophodon and Anabisetia. This and other similarities to South American ornithopods suggests that there may have been a distinct Southern Hemisphere ornithopod group, but at the time the authors cautioned that such an interpretation was not entirely justified. In 2015, the describers of Morrosaurus found that such a clade did indeed exist.[3]

Mineralized plates

Talenkauen's most distinct feature is a set of smooth, ovoid plates found along the side of the rib cage. These plates can be long (180 millimeters, or 7.1 in), but are very thin (only 3 millimeters thick [0.1 in]). They were present with at least the first eight ribs, attaching along the middle portion of a rib and lying flat.[2] Several other dinosaurs are known to have had similar plates, including Hypsilophodon, Othnielosaurus, Parksosaurus, Thescelosaurus,[4] and Macrogryphosaurus (also from Argentina, but from somewhat older rocks), which may have been related.[5] Because of the fragility of the plates, and the fact that they may not have always turned to bone in the living animal, they may have been more widespread than currently known. Novas and colleagues suggested that the plates may be homologous to uncinate processes, strip-like bony projections found on the ribs of a variety of animals including the tuatara, crocodiles, birds, and some maniraptoran theropod dinosaurs. In birds, uncinate processes help to ventilate the lungs, working with rib cage muscles, and Novas and colleagues proposed a similar function for the plates of Talenkauen.[2] This homology was rejected in a more recent study by Richard Butler and Peter Galton because of the plates' form.[4] The plates were too thin and limited in location to have been very useful as defensive devices.[2]

Paleobiology

Talenkauen skeleton
Reconstructed skeleton

Talenkauen, as a basal iguanodont, would have been a small, bipedal herbivore.[6] Other dinosaurs from the Pari Aike Formation include the giant titanosaurid Puertasaurus[7] and the predatory neovenatorid Orkoraptor.[8]

Classification

Through cladistic analysis, it was found to be more basal than Dryosaurus and Anabisetia, but more derived than Tenontosaurus and Gasparinisaura.[2] More recently, the describers of Macrogryphosaurus found their genus and Talenkauen to be related, and coined the clade Elasmaria for the two genera.[5] In 2015, several other Patagonian and Antarctic ornithopods were also found to be related.[3]

Cladogram based in the phylogenetic analysis of Rozadilla et al., 2015:

Hypsilophodon

Thescelosaurus

Iguanodontia
Elasmaria

Gasparinisaura

Morrosaurus

Trinisaura

Macrogryphosaurus

Notohypsilophodon

Talenkauen

Anabisetia

Parksosaurus

Kangnasaurus

Rhabdodontidae

Tenontosaurus

Dryomorpha

References

  1. ^ Varela, A. N.; Poiré, D. G.; Martin, T.; Gerdes, A.; Goin, F. J.; Gelfo, J. N.; Hoffmann, S. (2012). "U-Pb zircon constraints on the age of the Cretaceous Mata Amarilla Formation, Southern Patagonia, Argentina: Its relationship with the evolution of the Austral Basin". Andean Geology. 39 (3): 359–379. doi:10.5027/andgeoV39n3-a01.
  2. ^ a b c d e Novas, Fernando E.; Cambiaso, Andrea V; Ambrioso, Alfredo (2004). "A new basal iguanodontian (Dinosauria, Ornithischia) from the Upper Cretaceous of Patagonia". Ameghiniana. 41 (1): 75–82.
  3. ^ a b Rozadilla, Sebastián (2016). "A new ornithopod (Dinosauria, Ornithischia) from the Upper Cretaceous of Antarctica and its palaeobiogeographical implications". Cretaceous Research. 57: 311–324. doi:10.1016/j.cretres.2015.09.009.
  4. ^ a b Butler, Richard J.; Galton, Peter M. (2008). "The 'dermal armour' of the ornithopod dinosaur Hypsilophodon from the Wealden (Early Cretaceous: Barremian) of the Isle of Wight: a reappraisal". Cretaceous Research. 29 (4): 636–642. doi:10.1016/j.cretres.2008.02.002.
  5. ^ a b Calvo, J.O.; Porfiri, J.D.; Novas, F.E. (2007). "Discovery of a new ornithopod dinosaur from the Portezuelo Formation (Upper Cretaceous), Neuquén, Patagonia, Argentina". Arquivos do Museu Nacional. 65 (4): 471–483.
  6. ^ Norman, David B. (2004). "Basal Iguanodontia". In Weishampel, D.B.; Dodson, P.; Osmólska, H. (eds.). The Dinosauria (2nd ed.). Berkeley: University of California Press. pp. 413–437. ISBN 978-0-520-24209-8.
  7. ^ Novas, Fernando E.; Salgado, Leonardo; Calvo, Jorge; Agnolin, Federico (2005). "Giant titanosaur (Dinosauria, Sauropoda)from the Late Cretaceous of Patagonia" (PDF). Revisto del Museo Argentino de Ciencias Naturales, N.s. 7 (1): 37–41. doi:10.22179/REVMACN.7.344. Archived from the original (PDF) on 2006-08-22. Retrieved 2007-03-04.
  8. ^ Novas, F.E.; Ezcurra, M.D.; Lecuona, A. (2008). "Orkoraptor burkei nov gen. et sp., a large theropod from the Maastrichtian Pari Aike Formation, Southern Patagonia, Argentina". Cretaceous Research. 29 (3): 468–480. doi:10.1016/j.cretres.2008.01.001.

External links

Anabisetia

Anabisetia ( AH-nə-bee-SET-ee-ə) is a genus of iguanodont dinosaur from the Late Cretaceous Period of Patagonia, South America. It was a small bipedal herbivore, around 2 metres (6 ft 7 in) long.

Aralosaurini

Aralosaurini is a tribe of basal lambeosaurine hadrosaurs endemic to Eurasia. It currently contains Aralosaurus (from the Aral sea of Kazakhstan) and Canardia (from Toulouse, Southern France).

Canardia

Canardia is an extinct genus of aralosaurin lambeosaurine dinosaur known from the Late Cretaceous Marnes d’Auzas Formation (late Maastrichtian stage) of Toulouse, Haute-Garonne Department, southern France. The type species Canardia garonnensis was first described and named by Albert Prieto-Márquez, Fabio M. Dalla Vecchia, Rodrigo Gaete and Àngel Galobart in 2013.

Elasmaria

Elasmaria is a clade of iguanodont ornithopods known from Cretaceous deposits in South America, Antarctica, and Australia.

Fernando Novas

Fernando Emilio Novas is an Argentine paleontologist working for the Comparative Anatomy Department of the Bernardino Rivadavia Natural Sciences Museum in Buenos Aires, Argentina. Novas holds a PhD in Natural sciences.

Working for the CONICET, he described or co-described many dinosaurs, among them Abelisaurus, Aniksosaurus, Aragosaurus, Austroraptor, Chilesaurus, Megaraptor, Neuquenraptor, Orkoraptor, Patagonykus, Unenlagia, Araucanoraptor, Skorpiovenator, Tyrannotitan, Talenkauen, and Puertasaurus, most from the Patagonia region of Argentina. Chilesaurus diegosuarezi made the cover of Nature magazine on June 18, 2015.

Gasparinisaura

Gasparinisaura (meaning "Gasparini's lizard") is a genus of herbivorous ornithopod dinosaur from the Late Cretaceous.

The first fossils of Gasparinisaura were in 1992 found in Argentina, near Cinco Saltos in Río Negro Province. The type species, Gasparinisaura cincosaltensis, was named and described in 1996 by Rodolfo Coria and Leonardo Salgado. The generic name honours Argentine palaeontologist Zulma Brandoni de Gasparini. The specific name refers to Cinco Saltos.

Jaxartosaurus

Jaxartosaurus is a genus of hadrosaurid dinosaur similar to Corythosaurus which lived during the Late Cretaceous. Its fossils were found in Kazakhstan.

Laiyangosaurus

Laiyangosaurus ("Laiyang lizard") is a genus of saurolophine hadrosaurid from the Late Cretaceous of China. It is known from one species, L.youngi, found in the Laiyang Basin within the province of Shandong.

Lapampasaurus

Lapampasaurus is an extinct genus of hadrosaurid known from the Late Cretaceous Allen Formation (late Campanian or early Maastrichtian stage) of La Pampa Province, Argentina. It contains a single species, Lapampasaurus cholinoi.The generic name refers to the Argentine province of La Pampa. The specific name honours the late collector José Cholino. The material includes cervical, dorsal, sacral and caudal vertebrae, the forelimb girdle, and the partial hindlimb.

Macrogryphosaurus

Macrogryphosaurus (meaning "big enigmatic lizard") is a genus of basal iguanodont dinosaur from the Coniacian age Upper Cretaceous Sierra Barrosa Formation (Neuquén Group) of Patagonia, Argentina. It was described by Jorge Calvo and colleagues, with M. gondwanicus as type species (referring to the animal coming from Gondwana).

Morrosaurus

Morrosaurus is an extinct genus of herbivorous ornithischian dinosaur member of the Euornithopoda, that lived in the late Cretaceous in the Antarctica. The only known species is the type Morrosaurus antarcticus.

Notohypsilophodon

Notohypsilophodon (meaning "southern Hypsilophodon") is a genus of euornithopod dinosaur from the Late Cretaceous of Argentina. It was described as the only "hypsilophodont" known from South America, although this assessment is not universally supported, and Gasparinisaura is now believed to have been a basal euornithopod as well.

Osmakasaurus

Osmakasaurus is a genus of herbivorous iguanodontian dinosaur. It is a basal iguanodontian which lived during the lower Cretaceous period (Valanginian age) in what is now Buffalo Gap of South Dakota, United States. It is known from the Chilson Member of the Lakota Formation. This genus was named by Andrew T. McDonald in 2011 and the type species is Osmakasaurus depressus. O. depressus was previously referred to as Camptosaurus depressus, and was first described in 1909 by Charles W. Gilmore.

Plesiohadros

Plesiohadros is an extinct genus of hadrosauroid dinosaur. It is known from a partial skeleton including the skull collected at Alag Teg locality, from the Campanian Djadochta Formation of southern Mongolia. The type species is Plesiohadros djadokhtaensis.

Rhabdodon

Rhabdodon (meaning "fluted tooth") is a genus of ornithopod dinosaur that lived in Europe approximately 70–66 million years ago in the Late Cretaceous. It is similar in build to a very robust "hypsilophodont" (non-iguanodont ornithopod), though all modern phylogenetic analyses find this ("Hypsilophodontia/tidae") to be an unnatural grouping, and Rhabdodon to be a basal member of Iguanodontia.

Sahaliyania

Sahaliyania (from "black" in Manchu, a reference to the Amur/Heilongjiang River) is a genus of lambeosaurine hadrosaurid dinosaur (crested duckbilled dinosaur) from the Late Cretaceous of Heilongjiang, China.

Trinisaura

Trinisaura is an extinct genus of ornithopod dinosaur known from the lower levels of the Late Cretaceous Snow Hill Island Formation (lower Campanian stage) of James Ross Island, Antarctica. It contains a single species, Trinisaura santamartaensis.The species was in 2013 named by Rodolfo Aníbal Coria e.a. The generic name honours the geologist Trinidad Diaz. The specific name refers to the Santa Marta Cove site where the specimen was in 2008 found by Coria and Juan José Moly. That same year, the find was reported in the scientific literature.The holotype, MLP-III-1-1, consists of a partial skeleton lacking the skull, of a subadult individual about 1.5 metres (4.9 ft) in length.

Xuwulong

Xuwulong is a genus of hadrosauroid dinosaur from the Early Cretaceous period. It lived during the early Cretaceous period (Aptian-Albian age) in what is now Yujingzi Basin in the Jiuquan area, Gansu Province of northwestern China. It is known from the holotype – GSGM F00001, an articulated specimen including a complete cranium, almost complete axial skeleton, and complete left pelvic girdle from Xinminpu Group. Xuwulong was named by You Hailu, Li Daqing and Liu Weichang in 2011 and the type species is Xuwulong yueluni.

Zalmoxes

Zalmoxes is an extinct genus of rhabdodontid ornithopod dinosaur from the Maastrichtian of Romania. The genus is known from specimens first named as the species Mochlodon robustum in 1899 by Franz Nopcsa before being reclassified as Rhabdodon robustum by him in 1915. In 1990 this name was corrected to Rhabdodon robustus by George Olshevsky, and in 2003 the species was once more reclassified, this time as the type species Zalmoxes robustus. Zalmoxes refers to the Dacian deity Zalmoxis, and robustus to the robustness of the remains. In 2003 another species was named, Zalmoxes shqiperorum, named for the Albanian name for Albanians.

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