The name Ischigualasto is derived from the extinct Cacán language, spoken by an indigenous group referred to as the Diaguita by the Spanish conquistadors and means "place where the moon alights". Another hypothesis gives the name "Ischigualasto" a Quechua origin, meaning "dead land", although some scholars have proposed Huarpe roots. The first paleontological description of Ischigualasto dates from 1930. In 1941 the area was studied in more detail, which led to the discovery of 70 species of fossil plants. The region received for the first time the name Valle de la Luna in 1943, in a publication edited by the Automobil Club Argentino. That year, Dr. Ángel Cabrera of University of La Plata described the traversodontidExaeretodon—the first cynodont found in Ischigualasto—after samples sent by a geologist prospecting for coal on behalf of an Argentine mining company. Academic work and geological prospecting proceeded slowly until 1958, when Dr. Alfred Sherwood Romer, a Harvard University expert in ancient mammals, discovered several rich fossil beds which he described as "extraordinary".
Description
Most of the park lies within the Valle Fértil Department, with a minor part in the Jachal Department of San Juan, at an altitude of about amsl. The park is part of the western border of the Central Sierras, and it features typical desert vegetation which covers between 10 and 20% of the area. The climate is very dry, with rainfall mostly during the summer, and temperature extremes. There is a constant southern wind with a speed of after noon and until the evening, sometimes accompanied by the extremely strong Zonda wind.
Paleontology
The Ischigualasto Formation contains Late Triassic deposits, with some of the oldest known dinosaur remains, which are the world's foremost with regards to quality, number and importance. This allows for the study of the transition between dinosaurs and ancient mammals; research is ongoing. In the Carnian this area was a volcanically active floodplain dominated by rivers and had a strongly seasonal rainfall. Petrified tree trunks of Protojuniperoxylon ischigualastianus more than tall attest to a rich vegetation at that time. Fossil ferns and horsetails have also been found. Rhynchosaurs and cynodonts are by far the predominant findings among the tetrapodfossils 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. Dinosaurs of Ischigualasto Formation include early samples of the two major lineages of dinosaurs. The carnivorous archosaurHerrerasaurus 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.
