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Global correlation of the Triassic theropod record

A review of the geologic ages of all Late Triassic theropod dinosaurs.

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Abstract

Theropod dinosaur body fossils are known from Upper Triassic (Carnian-Rhaetian) strata in North and South America, Greenland, Europe, and India. Theropod footprints, usually assigned to the ichnogenus Grallator HITCHCOCK and related ichnotaxa, have been described from the Upper Triassic of North America, Greenland, Europe, and Africa. These theropod occurrences are readily correlated as latest Carnian, Norian, and Rhaetian records. The earliest theropods are among the first dinosaurs and appear essentially synchronously in the Upper Triassic of the United States, the United Kingdom, Brazil, Argentina, and India. These theropods include herrerasaurs and ceratosaurs from the lower Chinle Group in the southwestern United States, the problematic theropod Saltopus elginensis HUENE from the Lossiemouth Sandstone in Scotland, the herrerasaurid Staurikosaurus pricei COLBERT from the Santa Maria Formation in Brazil, the herrerasaurid Herrerasaurus ischigualastensis REIG and the basal theropod Eoraptor lunensis SERENO, FORESTER, ROGERS & MONETTA from the Ischigualasto Formation in Argentina, and the probable basal theropod Alwalkeria maleriensis (CHATTERJEE) from the Maleri Formation in India. All of these occurrences are of late Carnian age, approximately 228 Ma. Thus, the oldest dinosaurs are not from South America, as commonly claimed, but instead appear synchronously across Pangea in the upper Carnian fossil record of four modern continents.


There are several ceratosaurs and herrerasaurs of Norian age, including the herrerasaur Chindesaurus bryansmalli LONG & MURRY, several unnamed herrerasaurs, and at least two ceratosaurs from the middle Chinle Group, USA, as well as the ceratosaurs Procompsognathus triassicus HUENE and Liliensternus liliensterni (HUENE) and problematic theropods such as Halticosaurus HUENE from the Middle Stubensandstein, Germany. The Rhaetian fossil record of theropods is characterized by abundant tracks, particularly of the ichnogenus Grallator HITCHCOCK, in the USA, Europe, and Africa, and numerous theropods, including the Whitaker quarry theropods Coelophysis bauri COPE and Syntarsus? RAATH from the United States, the ceratosaur Liliensternus airelensis CUNY & GALTON and other, indeterminate forms from France, and a poorly known theropod fauna from the Los Colorados Formation of Argentina. With the notable exception of the Whitaker Quarry at Ghost RAnch, which preserves dozens of theropod skeletons, Late Triassic theropods never dominated the tetrapod predator guild.