Chañares Formation

Chañares Formation
Stratigraphic range: Early Carnian Late Triassic
Type Geologic formation
Location
Region La Rioja Province
Country Argentina

The Chañares Formation is geologic formation located in La Rioja Provence, Argentina.

It was originally thought to be formed during the Ladinian age of the Middle Triassic epoch, in the Triassic Period of the Mesozoic Era; Marsicano et al. (2016) dated it to early Carnian (236–234 Ma), Late Triassic.[1]

Fossils

Some localities are well known for their abundance of tetrapod fossils. Theraspids include the kannemeyeriid Dinodontosaurus, and cynodonts such as Probainognathus and Massetognathus, the latter being the most abundant tetrapod taxon in the formation.[2] Other notable tetrapods present from the formation are the archosaurs. Ornithodirans include Lewisuchus,[3] Lagerpeton,[4] Marasuchus,[5] and Pseudolagosuchus.[6] Other archosaurs include Gracilisuchus[7] and Luperosuchus.[8] Three proterochampsids are known from the formation, Tropidosuchus, Chanaresuchus, and Gualosuchus. They are very similar in appearance, but differ in size and cranial proportions.[9]

References

  1. ↑ Claudia A. Marsicano, Randall B. Irmis, Adriana C. Mancuso, Roland Mundil and Farid Chemale (2016). "The precise temporal calibration of dinosaur origins". Proceedings of the National Academy of Sciences of the United States of America 113 (3): 509–513. doi:10.1073/pnas.1512541112.
  2. ↑ Romer, A. S. (1967). "The Chañares (Argentina) Triassic reptile fauna. III. Two new gomphodonts, Massetognathus pascuali and M. teruggii". Breviora 264: 1–25.
  3. ↑ Romer, A. S. (1972). "The Chañares (Argentina) Triassic reptile fauna; XIV, Lewisuchus admixtus, gen. et sp. nov., a further thecodont from the Chañares beds". Breviora 390: 1–13.
  4. ↑ Romer, A. S. (1971). "The Chañares (Argentina) Triassic reptile fauna. X. Two new but incompletely known long-limbed pseudosuchians". Breviora 378: 1–10.
  5. ↑ Sereno, P. C.; Arcucci, A. B. (1994). "Dinosaurian precursors from the Middle Triassic of Argentina: Marasuchus lilloensis, gen. nov". Journal of Vertebrate Paleontology 14 (1): 53–73. doi:10.1080/02724634.1994.10011538.
  6. ↑ Arcucci, A. B. (1987). "Un nuevo Lagosuchidae (Thecodontia-Pseudosuchia) de la fauna de Los Chañares (Edad Reptil Chañarense, Triasico Medio), La Rioja, Argentina". Ameghiniana 24 (1-2): 89–94.
  7. ↑ Romer, A. S. (1972). "The Chañares (Argentina) Triassic reptile fauna. XIII. An early ornithosuchid pseudosuchian, Gracilisuchus stipanicicorum, gen. et sp. nov". Breviora 389: 1–24.
  8. ↑ Romer, A. S. (1971). "The Chañares (Argentina) Triassic reptile fauna. VIII. A fragmentary skull of a large thecodont, Luperosuchus fractus". Breviora 373: 1–8.
  9. ↑ Romer, A. S. (1971). "The Chañares (Argentina) Triassic reptile fauna. XI. Two new long-snouted thecodonts, Chanaresuchus and Gualosuchus". Breviora 379: 1–22.
Triassic Period
Lower/Early Triassic Middle Triassic Upper/Late Triassic
Induan |Olenekian Anisian | Ladinian Carnian | Norian
Rhaetian
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