respectively. The formation is approximately coeval with the upper Santa Maria Formation of the Paraná Basin in southeastern Brazil, the Pekin Formation of the United States and the lower Maleri Formation of India. Subdivision The Ischigualasto Formation is subdivided into four members, from top to bottom: Quebrada de la Sal ~ Valle de la Luna ~ Cancha de Bochas ~ La Peña ~ Paleontological significance The Ischigualasto Formation is highly fossiliferous and its unique paleontological characteristics made it a Lagerstätte; a stratigraphic unit containing a diverse faunal assemblage. The paleontological importance led to the establishment of the Ischigualasto Provincial Park, a UNESCO World Heritage Site since 2000. The Ischigualasto Formation contains Late Triassic (Carnian) deposits (231.4 -225.9 million years before the present), with some of the oldest known dinosaur remains, which are the world's foremost with regards to quality, number and importance. Rhynchosaurs and cynodonts (especially rhynchosaur Hyperodapedon and cynodont Exaeretodon) are by far the predominant findings among the tetrapod fossils in the park. A study from 1993 found dinosaur specimens to comprise only 6% of the total tetrapod sample; subsequent discoveries increased this number to approximately 11% of all findings. Carnivorous dinosaurs are the most common terrestrial carnivores of the Ischigualasto Formation, with herrerasaurids comprising 72% of all recovered terrestrial carnivores. The carnivorous archosaur Herrerasaurus is the most numerous of these dinosaur fossils. Another important putative dinosaur with primitive characteristics is Eoraptor lunensis, found in Ischigualasto in the early 1990s. Petrified tree trunks of Protojuniperoxylon ischigualastianus of more than tall attest to a rich vegetation at that time. Fossil ferns and horsetails have also been found in the formation. Coprolites were found in Valle Pintado in the upper part of the formation. Analysis of the coprolites revealed that plant remains were absent and bone material and apatite were sparse. The most likely candidate to have produced these fossil feces has been suggest as the most common reptile in the formation; Herrerasaurus. Fossil content Dinosaurs The fossils of an undescribed species of theropod are present in San Juan Province. Other reptiles Synapsids Temnospondyls Plants See also Quebrada del Barro Formation, contemporaneous fossiliferous formation of the Marrayel-El Carrizal Basin Candelária Formation, contemporaneous fossiliferous formation of the Paraná Basin Molteno Formation, contemporaneous fossiliferous formation of the Karoo Basin in southern Africa Fremouw Formation, contemporaneous fossiliferous formation of Antarctica Denmark Hill Insect Bed, contemporaneous fossiliferous unit of Queensland, Australia Madygen Formation, contemporaneous Lagerstätte