Ischigualasto

Ischigualasto / Talampaya Natural Parks *
Country Argentina
Type Natural
Criteria viii
Reference 966
Region ** Latin America and the Caribbean
Inscription history
Inscription 2000 (24th Session)
Location of Ischigualasto in Argentina
* Name as inscribed on World Heritage List
** Region as classified by UNESCO

Ischigualasto is a geological formation and a natural park associated with it in the province of San Juan, north-western Argentina, near the border with Chile. The Ischigualasto Provincial Park is located in the north-east of the province (), and its northern border is the Talampaya National Park, in La Rioja, both of which belong to the same geological formation.

Contents

Description

It has an area of 603.7 km2 (233 sq mi), most of them within the Valle Fértil Department, with a minor part in the Jachal Department of San Juan, at an altitude of about 1,300 m (4,265 ft) above mean sea level. The park is part of the western border of the Pampean Hills, and it features typical desert vegetation (bushes, cacti and some trees) which covers between 10 and 20% of the area. The climate is very dry, with rainfall mostly during the summer, and temperature 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.

Paleontology

The Ischigualasto Formation contains Late Triassic (Carnian) deposits (231.4 -225.9 million years before the present[1]), with some of the oldest known dinosaur 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 dinosaurs and ancient mammals; 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 active floodplain dominated by rivers 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 ferns and horsetails have also been found.

Rhynchosaurs and cynodonts are by far the predominant findings among the tetrapod fossils in the park. Dinosaurs comprise only 6% of the findings, but these include early samples of the two major lineages of dinosaurs (ornithischians and saurischians). 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.

Dinosaurs

An undescribed theropod is present in San Juan Province.[2]

Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative data are in small text; crossed out data are discredited.
Dinosaurs of the Ischigualasto Formation
Genus Species Location Stratigraphic position Material Notes Images

Chromogisaurus

Eodromaeus

E. murphi

Valle de la Luna Member

A nearly complete skeleton and another partial skeleton.

Basal theropod

Eoraptor[2]

E. lunensis[2]

San Juan Province.[2]

Two nearly complete skeletons.[3]

Basal saurischian, possibly a theropod or sauropodomorph

Frenguellisaurus[2]

F. ischigualastensis[2]

San Juan Province.[2]

Jr. synonym of Herrerasaurus ischigualastensis.

Herrerasaurus[2]

H. ischigualastensis[2]

San Juan Province.[2]

"Various partial skeletons, including a complete skull and mandible."[3]

Includes Ischisaurus cattoi, Frenguellisaurus ischigualastensis, and cf. Staurikosaurus sp.[2]

Ischisaurus[2]

I. cattoi[2]

San Juan Province.[2]

Jr. synonym of Herrerasaurus ischigualastensis.

Panphagia[4]

P. protos[4]

San Juan Province.[2]

The basalmost known genus of sauropodomorph.[4]

Pisanosaurus[2]

P. mertii[2]

the La Rioja Province.[2]

"Fragmentary skull and skeleton."[5]

Sanjuansaurus

cf. Staurikosaurus

Indeterminate

San Juan Province.[2]

Remains previously referred to "cf. Staurikosaurus" were later determined to belong to Herrerasaurus.[2]

See also

Footnotes

  1. ^ Ricardo N. Martinez, Paul C. Sereno, Oscar A. Alcober, Carina E. Colombi, Paul R. Renne, Isabel P. Montañez and Brian S. Currie (2011). "A Basal Dinosaur from the Dawn of the Dinosaur Era in Southwestern Pangaea". Science 331 (6014): 206–210. doi:10.1126/science.1198467. PMID 21233386. http://www.sciencemag.org/content/331/6014/206.abstract. 
  2. ^ a b c d e f g h i j k l m n o p q r s t Weishampel, David B; et al. (2004). "Dinosaur distribution (Late Triassic, South America)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 527–528. ISBN 0-520-24209-2.
  3. ^ a b "Table 2.1," in Weishampel, et al. (2004). Page 26.
  4. ^ a b c Martinez RN, Alcober OA (2009) A Basal Sauropodomorph (Dinosauria: Saurischia) from the Ischigualasto Formation (Triassic, Carnian) and the Early Evolution of Sauropodomorpha. PLoS ONE 4(2): e4397. doi:10.1371/journal.pone.0004397
  5. ^ "Table 14.1," in Weishampel, et al. (2004). Page 326.

References

Spanish language references