The Ischigualasto Tetrapod Assemblage (Late Triassic, Argentina) and 40 Ar/ 39 Ar Dating of Dinosaur Origins
- 7 May 1993
- journal article
- other
- Published by American Association for the Advancement of Science (AAAS) in Science
- Vol. 260 (5109) , 794-797
- https://doi.org/10.1126/science.260.5109.794
Abstract
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 years ago, the major dinosaurian lineages were established, and theropods were already important constituents of the carnivorous tetrapod guild in the Ischigualasto—Villa Unión Basin. Dinosaurs as a whole remained minor components of tetrapod faunas for at least another 10 million years.Keywords
This publication has 17 references indexed in Scilit:
- The pectoral girdle and forelimb of the basal theropodHerrerasaurus ischigualastensisJournal of Vertebrate Paleontology, 1994
- Primitive dinosaur skeleton from Argentina and the early evolution of DinosauriaNature, 1993
- The Complete Skull and Skeleton of an Early DinosaurScience, 1992
- Coeval 40 Ar/ 39 Ar Ages of 65.0 Million Years Ago from Chicxulub Crater Melt Rock and Cretaceous-Tertiary Boundary TektitesScience, 1992
- The oldest dinosaursThe Science of Nature, 1992
- What really happened in the late Triassic?Historical Biology, 1991
- Lesothosaurus, “Fabrosaurids,” and the early evolution of OrnithischiaJournal of Vertebrate Paleontology, 1991
- More than one event in the late Triassic mass extinctionNature, 1986
- Subcommission on geochronology: Convention on the use of decay constants in geo- and cosmochronologyEarth and Planetary Science Letters, 1977
- The Niche Exploitation Pattern of the Blue‐Gray GnatcatcherEcological Monographs, 1967