Loncosaurus

Taxobox
name = "Loncosaurus"
fossil_range = Upper Cretaceous
status = Fossil
regnum = Animalia
phylum = Chordata
classis = Sauropsida
superordo = Dinosauria
ordo = Ornithischia
subordo = Ornithopoda
familia = unknown
genus = "Loncosaurus"
genus_authority = Ameghino, 1898 or 1899
binomial = "Loncosaurus argentinus"

"Loncosaurus" (meaning uncertain; either Araucanian "chief" or Greek "lance" "lizard" [http://www.dinosauria.com/dml/names/dinol.htm Dinosaur Translation Guide L] ] ) was a genus of ornithopod dinosaur from the Upper Cretaceous of Provincia de Santa Cruz, Argentina. The type (and only known) species is "Loncosaurus argentinus", described by the famous Argentinian paleontologist Florentino Ameghino, but is considered a dubious name. Details on this animal are often contradictory, befitting a genus that was long confused for a theropod.

History

Ameghino named this dinosaur in either 1898Ameghino, F. 1898. Sinopsis geológico-paleontológica. "Segundo conso de la República Argentina". Folia:Buenos Aires, 1:112-255. [Spanish] ] Norman, D.B., and Weishampel, D.B. 1990. Iguanodontidae and related ornithopods. In: Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.). "The Dinosauria". University of California Press:Berkeley, 510-533. ISBN 0-520-06727-4] Norman, D.B. 2004. Basal Iguanodontia. In: Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.). "The Dinosauria" (second edition). University of California Press:Berkeley, 413-437. ISBN 0-520-24209-2] George Olshevsky's [http://members.aol.com/Dinogeorge/dinolist.html Dinosaur Genera List] ] or 1899,Ameghino, F. 1899. Nota preliminar sobre el "Loncosaurus argentinus", un representante de la familia Megalosauridae de la República Argentina. "Anales de la Sociedad Cientifica Argentina" 49:61-62. [Spanish] ] Coria, R.A., and Salgado, L. 1996. "Loncosaurus argentinus" Ameghino, 1899 (Ornithischia, Ornithopoda): a revised description with comments on its phylogenetic relationships. "Ameghiniana" 33(4):373-376.] Glut, D.F. (1997). "Dinosaurs: The Encyclopedia". Mcfarland & Company, Inc., xi-1076. ISBN 0899509177] Coria, R.A. 1999. Ornithopod dinosaurs from the Neuquén Group, Patagonia, Argentina: phylogeny and biostratigraphy. In Tomida, Y., Rich, T.H., and Vickers-Rich, P. (eds.) "Proceedings of the Second Gondwanan Dinosaur Symposium, National Science Museum Monographs" 15:47-60.] [http://paleodb.org/cgi-bin/bridge.pl?user=Guest&action=displayHomePage The Paleobiology Database] )] from a proximal femur (MACN-1629) and tooth found near Rio Sehuen, Santa Cruz, in either the Cardiel Formation (most sources) or the Matasiete Formation (both being Upper Cretaceous).

Either way, he thought the remains belonged to a "megalosaurid" dinosaur, a carnivore, which Friedrich von Huene agreed with.von Huene, F. 1909. Skizze zu einer Systematik und Stammesgeschichte der Dinosaurier. "Centralblatt für Mineralogie, Geologie und Paläontologie" 1909:12-22. [German] ] Upon further review, von Zittel assigned it to the Coeluridae,von Zittel, K.A.. 1911. "Grundzüge der Paläontologie (Paläozoologie)." II. Abteilung. Vertebrata. Druck und Verlag von R. Oldenbourg:München, 1-598. [German] ] recognized today as a "wastebasket taxon" for small carnivorous dinosaurs. The carnivore tooth helped this misidentification take hold.

It was ignored for decades until Ralph Molnar reassessed it.Molnar, R.E. 1980. Australian late Mesozoic continental tetrapods: some implications. "Mémoires de la Société Géologique de France, Nouvelle Série" 139:131-143.] He found that the tooth did not belong to the same animal as the femur and removed it from the type, and suggested that the femur belonged to a hypsilophodont or turtle. Professional opinion has not changed much since then, although based on size, it appears more likely to be an iguanodont than a hypsilophodont. Reviews either put it at Ornithopoda "incertae sedis" or Iguanodontia. Oddly, a semipopular reference reassigned it to "Genyodectes" without comment,Lessem, D., and Glut, D.F. 1993. "The Dinosaur Society Dinosaur Encyclopedia". Random House, Inc.:New York, 533 p. ISBN 0-679-41770-2] a view which has not been followed since.

Paleobiology

Coria estimates the size of the "Loncosaurus" type individual at about 5 m (16.4 feet) long. As a small to medium-sized ornithopod, it would have been an agile bipedal herbivore.

References

External links

* http://www.users.qwest.net/~jstweet1/ornithopoda.htm