The Ischigualasto Tetrapod Assemblage (Late Triassic, Argentina) and 40Ar/39Ar Dating of Dinosaur Origins

  title={The Ischigualasto Tetrapod Assemblage (Late Triassic, Argentina) and 40Ar/39Ar Dating of Dinosaur Origins},
  author={Raymond R. Rogers and Carl C. Swisher and Paul C. Sereno and Alfredo M. Monetta and Catherine A Forster and Ricardo N. Mart�nez},
  pages={794 - 797}
40Ar/39Ar dating of sanidine from a bentonite interbedded in the Ischigualasto Formation of northwestern Argentina yielded a plateau age of 227.8 � 0.3 million years ago. This middle Carnian age is a direct calibration of the Ischigualasto tetrapod assemblage, which includes some of the best known early dinosaurs. This age shifts last appearances of Ischigualasto taxa back into the middle Carnian, diminishing the magnitude of the proposed late Carnian tetrapod extinction event. By 228 million… 

A Basal Dinosaur from the Dawn of the Dinosaur Era in Southwestern Pangaea

A previously unidentified basal theropod is described, its contemporary Eoraptor is reassessed as a basal sauropodomorph, the faunal record of the Ischigualasto Formation is divided with biozones, and the formation is bracketed with 40Ar/39Ar ages.

A Late Triassic Dinosauromorph Assemblage from New Mexico and the Rise of Dinosaurs

The transition between the first dinosaurs and more archaic faunas may have extended for 15 to 20 million years and was probably diachronous at different paleolatitudes.

A sauropodomorph dinosaur from the Upper Triassic (Carnian) of southern Brazil Un dinosaure sauropodomorphe dans le Trias sup&few (Carnien) du sud du Brksil

Three newly discovered skeletons from the Carnian red beds of the Santa Maria Formation, south Brazil, represent one of the oldest dinosaurs ever found. The new taxon, Saturnalia tupiniquim, is

New dinosaur remains from the Late Triassic of southern Brazil (Candelária Sequence, Hyperodapedon Assemblage Zone)

Pretto, F.A., Schultz, C.L., Langer, M.C. 4.02.2015. New dinosaur remains from the Late Triassic of southern Brazil (Candelária Sequence, Hyperodapedon Assemblage Zone). Alcheringa 39, xxx–xxx. ISSN


Abstract:  This paper contains the first comprehensive ichnotaxonomic review of the Triassic tetrapod track record in Argentina, including previous accounts and new material recently discovered, and


The Rosario do Sul Group is one of the better-known tetrapod-bearing continental deposits of Triassic age. It crops out in central Rio Grande do Sul, south Brazil, and has yielded a fauna of more

A new Late Triasssic phytogeographical scenario in westernmost Gondwana.

The Onslow floral belt is extended, previously recognized from the western edge of Tethys to Timor, to the western margin of South America, which has implications for palaeophytogeography, palaeoclimate reconstructions and the palaeoecology of a Triassic ecosystem.



The Beginning of the age of dinosaurs : faunal change across the Triassic-Jurassic boundary

  • K. Padian
  • Environmental Science, Geography
  • 1986
Preface Introduction Part I. The Beginning of the Age of Dinosaurs: The Time and the Setting: 1. Historical aspects of the Triassic-Jurassic boundary problem Edwin H. Colbert 2. Fossil plants and the

Primitive dinosaur skeleton from Argentina and the early evolution of Dinosauria

The discovery of Eoraptor supports the hypothesis that dinosaurs diverged rapidly at small body size from a common ancestor, with the principal herbivorous and carnivorous lineages present by the middle Carnian.

Faunal replacement in the Triassic of South America

Improvements in the locomotor apparatus are discernible in seven groups of archosaurs and indicate that a great adaptive radiation took place before the oldest recorded fauna dominated by archosaurs appeared.

The Complete Skull and Skeleton of an Early Dinosaur

Fossils of Herrerasaurus and younger dinosaurs from Upper Triassic beds in Argentina suggest that the dinosaurian radiation was well under way before dinosaurs dominated terrestrial vertebrate communities in taxonomic diversity and abundance.


  • Robert T Barker
  • Environmental Science, Geography
    Evolution; international journal of organic evolution
  • 1971
The fossil evidence strongly suggests that no small dinosaurs ever existed in either Jurassic or Cretaceous, and the most convincing proof of the lack of truly small dinosaur species is their absence in the carefully studied microvertebrate concentrates.

More than one event in the late Triassic mass extinction

  • M. Benton
  • Geography, Environmental Science
  • 1986
The recent hypothesis that mass extinctions are discrete phenomena that have occurred with great regularity during the history of life1,2 is testable in several ways. Two essential elements of the

Lesothosaurus, “Fabrosaurids,” and the early evolution of Ornithischia

New materials of Lesothosaurus diagnosticus permit a detailed understanding of one of the earliest and most primitive ornithischians and suggests long-axis rotation of the mandibular rami during mastication.

Counting individuals in mammalian fossil assemblages from fluvial environments

Many paleoecological analyses utilize estimates of the relative abundances of taxa in fossil or subfossil assemblages. Such estimates depend upon determination of the number of individuals present or