A reappraisal of the Late Cretaceous Argentinean titanosaur Argyrosaurus and a new genus
Publicado por Leonardo Filippi en 13:38
Phil Mannion and Alelandro Otero
Abstract. Argyrosaurus
superbus is one of the earliest-named Argentinean
dinosaurs. The holotype comprises a complete forelimb, probably from the upper
member of the Bajo Barreal Formation (Late Cretaceous), Chubut Province.
Numerous remains have been referred to Argyrosaurus
from Argentina and Uruguay; however, the
type specimen has not been adequately diagnosed and referrals have
predominantly been based upon their large size. Here we redescribe Argyrosaurus, demonstrating
it to be a valid titanosaur genus based on five autapomorphies, as well as an
unique character combination. The exact placement of Argyrosaurus within
Titanosauria is uncertain, although the probable presence of carpal bones,
otherwise unknown in titanosaurs, may indicate a basal position. None of the
referred remains can be attributed to Argyrosaurus, and most should be regarded as indeterminate
titanosauriforms. The exception to this is a partial skeleton from the lower
member of the Bajo Barreal Formation (early Late Cretaceous), Chubut Province,
comprising dorsal and caudal vertebrae, as well as numerous appendicular
elements. This specimen is distinct from Argyrosaurus
and can also be differentiated from other sauropods
based on an unusual character combination (including plesiomorphic tarsus),
plus one autapomorphy. Elaltitan lilloi,
gen. et sp. nov., displays numerous titanosaur characters and shares several
features with derived taxa such as Neuquensaurus, Opisthocoelicaudia, Rapetosaurus, Saltasaurus, and Trigonosaurus. Elaltitan can be referred to Lithostrotia; however, its precise position
within this clade must await future phylogenetic analysis. The revision and
description of the titanosaurs Argyrosaurus
and Elaltitan
provides new information on this diverse
but still poorly understood clade.
Philip D. Mannion & Alejandro
Otero (2012): A reappraisal of the Late Cretaceous Argentinean sauropod dinosaur
Argyrosaurus superbus, with a description of a new titanosaur genus, Journal of
Vertebrate Paleontology, 32:3, 614-638.
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