Ischigualasto is a geological formation and a natural park associated with it in the province

Provinces of Argentina

Argentina is subdivided into twenty-three provinces and one autonomous city...

 of San Juan

San Juan Province (Argentina)

San Juan is a province of Argentina, located in the western part of the country. Neighbouring provinces are, moving clockwise from the north, La Rioja, San Luis and Mendoza. It borders with Chile at the west....

, north-western Argentina

Argentina

Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...

, near the border with Chile

Chile

Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

. The Ischigualasto Provincial Park is located in the north-east of the province (30°S 68°W), and its northern border is the Talampaya National Park

Talampaya National Park

Talampaya National Park is a national park located in the east/centre of La Rioja Province, Argentina. It was designated a provincial reserve in 1975, a national park in 1997, and a UNESCO World Heritage Site in 2000....

, in La Rioja

La Rioja Province (Argentina)

La Rioja is a one of the provinces of Argentina and is located in the west of the country. Neighboring provinces are from the north clockwise Catamarca, Córdoba, San Luis and San Juan.-History:...

, both of which belong to the same geological formation.

Description

It has an area of 603.7 km² (233 sq mi), most of them within the Valle Fértil Department

Valle Fértil Department

Valle Fértil is a department located in the province of San Juan . Characterized by highly fertile landscapes and placed within its surface Ischigualasto Provincial Park, also known asValley of the Moon, which is heavily visited by tourists from around the world.- Origin of name :The Spaniards,...

, with a minor part in the Jachal Department

Jáchal Department

Jáchal is a department of the province of San Juan . It is located north of the same by making, characterized by its first level agricultural production, which emphasizes the planting of onion...

 of San Juan, at an altitude

Altitude

Altitude or height is defined based on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The reference datum also often varies according to the context...

 of about 1300 m (4,265 ft) above mean sea level

Above mean sea level

The term above mean sea level refers to the elevation or altitude of any object, relative to the average sea level datum. AMSL is used extensively in radio by engineers to determine the coverage area a station will be able to reach...

. The park is part of the western border of the Pampean Hills, and it features typical desert vegetation (bushes

Shrub

A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...

, cacti

Cactus

A cactus is a member of the plant family Cactaceae. Their distinctive appearance is a result of adaptations to conserve water in dry and/or hot environments. In most species, the stem has evolved to become photosynthetic and succulent, while the leaves have evolved into spines...

 and some trees) which covers between 10 and 20% of the area. The climate

Climate

Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and other meteorological elemental measurements in a given region over long periods...

 is very dry, with rainfall mostly during the summer, and temperature

Temperature

Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...

 extremes (minimum -10 °C, maximum 45 °C). There is a constant southern wind with a speed of 20-40 km/h after noon and until the evening, sometimes accompanied by an extremely strong zonda wind

Zonda wind

Zonda wind is a regional term for the foehn wind that often occurs on the eastern slope of the Andes, in Argentina. The Zonda is a dry wind which comes from the polar maritime air, warmed by descent from the crest, which is some 6,000 m above sea level...

.

Paleontology

The Ischigualasto Formation contains Late Triassic

Triassic

The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...

 (Carnian

Carnian

The Carnian is the lowermost stage of the Upper Triassic series . It lasted from about 228.7 till 216.5 million years ago . The Carnian is preceded by the Ladinian and is followed by the Norian...

) deposits (231.4 -225.9 million years before the present), with some of the oldest known dinosaur

Dinosaur

Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

 remains, which are the world's first with regards to quality, number and importance. It is the only place in the world where nearly all of the Triassic is represented in an undisturbed sequence of rock deposits. This allows for the study of the transition between dinosaur

Dinosaur

Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

s and ancient mammal

Mammal

Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s; research is ongoing.
The arid badlands around the formation are known as Valle de la Luna ("Valley of the Moon") due to their rugged, otherworldly appearance. In the Carnian this area was a volcanically

Volcano

2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...

 active floodplain

Floodplain

A floodplain, or flood plain, is a flat or nearly flat land adjacent a stream or river that stretches from the banks of its channel to the base of the enclosing valley walls and experiences flooding during periods of high discharge...

 dominated by river

River

A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...

s and had a strongly seasonal rainfall. Petrified tree trunks of Protojuniperoxylon ischigualastianus more than 40 m (131 ft) tall attest to a rich vegetation at that time. Fossil fern

Fern

A fern is any one of a group of about 12,000 species of plants belonging to the botanical group known as Pteridophyta. Unlike mosses, they have xylem and phloem . They have stems, leaves, and roots like other vascular plants...

s and horsetail

Horsetail

Equisetum is the only living genus in the Equisetaceae, a family of vascular plants that reproduce by spores rather than seeds.Equisetum is a "living fossil", as it is the only living genus of the entire class Equisetopsida, which for over one hundred million years was much more diverse and...

s have also been found.

Rhynchosaur

Rhynchosaur

Rhynchosaurs were a group of Triassic diapsid reptiles related to the archosaurs.-Description:Rhynchosaurs were herbivores, and at times abundant , with stocky bodies and a powerful beak...

s and cynodont

Cynodont

Cynodontia or cynodonts are a taxon of therapsids which first appeared in the Late Permian and were eventually distributed throughout all seven continents by the Early Triassic . This clade includes modern mammals and their extinct close relatives. They were one of the most diverse groups of...

s are by far the predominant findings among the tetrapod fossils in the park. Dinosaur

Dinosaur

Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

s comprise only 6% of the findings, but these include early samples of the two major lineages of dinosaurs (ornithischians and saurischians). The carnivorous archosaur

Archosaur

Archosaurs are a group of diapsid amniotes whose living representatives consist of modern birds and crocodilians. This group also includes all extinct non-avian dinosaurs, many extinct crocodilian relatives, and pterosaurs. Archosauria, the archosaur clade, is a crown group that includes the most...

 Herrerasaurus

Herrerasaurus

Herrerasaurus was one of the earliest dinosaurs. All known specimens of this carnivore have been discovered in rocks of late Ladinian age in northwestern Argentina...

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.

Dinosaurs

An undescribed theropod is present in San Juan Province.

Dinosaur Dinosaur Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of... s of the Ischigualasto Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Chromogisaurus Chromogisaurus Chromogisaurus is a sauropodomorph which existed in Argentina during the late Triassic period.Chromogisaurus was first named by Martín Daniel Ezcurra in 2010, and the type species is Chromogisaurus novasi. The generic name is derived from Greek chroma, "colour", and gè, "earth", a reference to the...
Eodromaeus Eodromaeus Eodromaeus is an extinct genus of basal theropod dinosaur known from the Late Triassic period of Argentina. It has been cited by Sereno as resembling a supposed common ancestor to all dinosaurs, the "Eve" of the dinosaurs....	E. murphi		Valle de la Luna Member	A nearly complete skeleton and another partial skeleton.	Basal theropod
Eoraptor Eoraptor Eoraptor was one of the world's earliest dinosaurs. It was a two-legged saurischian, close to the ancestry of theropods and sauropodomorphs. It lived ca. 231.4 million years ago, in what is now the northwestern region of Argentina...	E. lunensis	San Juan Province San Juan Province (Argentina) San Juan is a province of Argentina, located in the western part of the country. Neighbouring provinces are, moving clockwise from the north, La Rioja, San Luis and Mendoza. It borders with Chile at the west.... .		Two nearly complete skeletons.	Basal saurischian, possibly a theropod or sauropodomorph
Frenguellisaurus	F. ischigualastensis	San Juan Province San Juan Province (Argentina) San Juan is a province of Argentina, located in the western part of the country. Neighbouring provinces are, moving clockwise from the north, La Rioja, San Luis and Mendoza. It borders with Chile at the west.... .			Jr. synonym of Herrerasaurus ischigualastensis.
Herrerasaurus Herrerasaurus Herrerasaurus was one of the earliest dinosaurs. All known specimens of this carnivore have been discovered in rocks of late Ladinian age in northwestern Argentina...	H. ischigualastensis	San Juan Province San Juan Province (Argentina) San Juan is a province of Argentina, located in the western part of the country. Neighbouring provinces are, moving clockwise from the north, La Rioja, San Luis and Mendoza. It borders with Chile at the west.... .		"Various partial skeletons, including a complete skull and mandible."	Includes Ischisaurus cattoi, Frenguellisaurus ischigualastensis, and cf. Staurikosaurus Staurikosaurus Staurikosaurus is a genus of herrerasaurid dinosaur from the Late Triassic of Brazil.-Discovery:The first known specimen of Staurikosaurus was recovered from the Paleontological Site Jazigo Cinco of the Santa Maria Formation in the geopark of paleorrota , Rio Grande do Sul, southern Brazil... sp.
Ischisaurus	I. cattoi	San Juan Province San Juan Province (Argentina) San Juan is a province of Argentina, located in the western part of the country. Neighbouring provinces are, moving clockwise from the north, La Rioja, San Luis and Mendoza. It borders with Chile at the west.... .			Jr. synonym of Herrerasaurus ischigualastensis.
Panphagia Panphagia Panphagia is a genus of sauropodomorph dinosaur described in 2009. It lived 231 million years ago, during the late Ladinian age of the mid Triassic period , in what is now northwestern Argentina...	P. protos	San Juan Province.			The basalmost known genus of sauropodomorph.
Pisanosaurus Pisanosaurus Pisanosaurus is a genus of primitive ornithischian dinosaur from the Late Triassic of what is now South America. It was a bipedal herbivore described by Argentine paleontologist Rodolfo Casamiquela in 1967. Only one species, the type, Pisanosaurus mertii, is known, based on a single partial skeleton...	P. mertii	the La Rioja Province La Rioja Province (Argentina) La Rioja is a one of the provinces of Argentina and is located in the west of the country. Neighboring provinces are from the north clockwise Catamarca, Córdoba, San Luis and San Juan.-History:... .		"Fragmentary skull and skeleton."
Sanjuansaurus Sanjuansaurus Sanjuansaurus is a genus of herrerasaurid dinosaur from the Late Triassic-age Ischigualasto Formation of northwestern Argentina...
cf. Staurikosaurus Staurikosaurus Staurikosaurus is a genus of herrerasaurid dinosaur from the Late Triassic of Brazil.-Discovery:The first known specimen of Staurikosaurus was recovered from the Paleontological Site Jazigo Cinco of the Santa Maria Formation in the geopark of paleorrota , Rio Grande do Sul, southern Brazil...	Indeterminate	San Juan Province San Juan Province (Argentina) San Juan is a province of Argentina, located in the western part of the country. Neighbouring provinces are, moving clockwise from the north, La Rioja, San Luis and Mendoza. It borders with Chile at the west.... .			Remains previously referred to "cf. Staurikosaurus Staurikosaurus Staurikosaurus is a genus of herrerasaurid dinosaur from the Late Triassic of Brazil.-Discovery:The first known specimen of Staurikosaurus was recovered from the Paleontological Site Jazigo Cinco of the Santa Maria Formation in the geopark of paleorrota , Rio Grande do Sul, southern Brazil... " were later determined to belong to Herrerasaurus Herrerasaurus Herrerasaurus was one of the earliest dinosaurs. All known specimens of this carnivore have been discovered in rocks of late Ladinian age in northwestern Argentina... .