Talenkauen
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| Talenkauen Fossil range: Late Cretaceous |
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Talenkauen (meaning "small skull" in Aonikenk, referring to the proportionally small skull) is a genus of basal iguanodont dinosaur from the Maastrichtian-age Upper Cretaceous Pari Aike Formation of Lake Viedma, 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.[1]
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[edit] Description
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 ft). 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 the authors cautioned that all of the evidence together does not permit such an interpretation. The authors, through cladistic analysis, found the new genus to be more basal than Dryosaurus and Anabisetia, but more derived than Tenontosaurus and Gasparinisaura.[1] More recently, the describers of Macrogryphosaurus found their genus and Talenkauen to be related, and coined the clade Elasmaria for the two genera.[2]
[edit] 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 laying flat.[1] Two other dinosaurs have similar plates. One is Thescelosaurus, a hypsilophodont from rocks of a similar age in North America, but the two genera do not appear to be closely related.[1] The other is the somewhat older Macrogryphosaurus (also from Argentina), which may be related.[2] 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 we know. 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, so perhaps the plates functioned in the breathing mechanics of Talenkauen. The plates were too thin and limited in location to have been very useful as defensive devices.[1]
[edit] Paleobiology
Talenkauen, as a basal iguanodont, would have been a small, bipedal herbivore.[3] Other dinosaurs from the same formation include the giant titanosaurid Puertasaurus and a large, derived, unnamed tetanuran theropod.[4]
[edit] References
- ^ a b c d e Novas, Fernando E.; Cambiaso, Andrea V; and Ambrioso, Alfredo (2004). "A new basal iguanodontian (Dinosauria, Ornithischia) from the Upper Cretaceous of Patagonia". Ameghiniana 41 (1): 75–82.
- ^ a b Calvo, J.O.; Porfiri, J.D.; and 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.
- ^ Norman, David B. (2004). "Basal Iguanodontia", in Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.): The Dinosauria, 2nd, Berkeley: University of California Press, pp. 413-437. ISBN 0-520-24209-2.
- ^ Novas, Fernando E.; Salgado, Leonardo; Calvo, Jorge; and Agnolin, Federico (2005). "Giant titanosaur (Dinosauria, Sauropoda)from the Late Cretaceous of Patagonia". Revisto del Museo Argentino de Ciencias Naturales, n.s. 7 (1): 37–41.
[edit] External links
- National Geographic news release on Talenkauen; the National Geographic Society was one of the supporters of the research on this dinosaur.
- Restoration of Talenkauen, by Gabriel Lio.
