Quebrada del Barro Formation

Add links
Coordinates: 31°54′S 67°12′W / 31.9°S 67.2°W / -31.9; -67.2
Source: Wikipedia, the free encyclopedia.
Quebrada del Barro Formation
Approximate paleocoordinates
40°48′S 30°00′W / 40.8°S 30.0°W / -40.8; -30.0
RegionSan Juan Province
Country Argentina
ExtentMarayes-El Carrizal Basin
Quebrada del Barro Formation is located in Argentina
Quebrada del Barro Formation

The Quebrada del Barro Formation is a geological

formation of the Marayes-El Carrizal Basin in San Juan Province, Argentina. This formation is the most fossiliferous portion of the Triassic Marayes Group, and is also the youngest unit of the group, overlying the El Carrizal Formation. An unconformity at the top of the Quebrada del Barro Formation separates it from the Cretaceous-age Los Riscos Formation of the El Gigante Group.[1][2][3][4] Part of the formation may be made into a provincial park following the discovery of the fossils of Ingentia, a giant sauropodomorph dinosaur which helped elucidate the early evolution of sauropods.[5]

Sedimentology

The Quebrada del Barro Formation formed within a rift basin during a period of renewed fracturing. It encompasses 600 to 1,400 metres (2,000 to 4,600 ft) of red sandstones, fine conglomerates, and diamictites.[3] Early hypotheses on the depositional environment proposed that the sediments formed in an alluvial fan or braided river system, while a newer proposal outlines how four different facies within the formation can be used to reconstruct a meandering semiarid floodplain deposited by mudflows and discharging in heterolithic terminal splays.[6]

Fossil content

The fauna of Quebrada del Barro is similar to that of the neighboring

cynodonts, and testudinatans. However, Quebrada del Barro is more abundant in sphenodontians (Sphenotitan), tritheledontid cynodonts, and coelophysoid dinosaurs (Lucianovenator), while sauropodomorphs are somewhat less common and aetosaurs are completely absent, in contrast to the Los Colorados Formation.[3] Sphenodontians and cynodonts are also abundant in microfossil assemblages.[6] In addition, the Quebrada del Barro Formation preserves some of the only pterosaur and Dromomeron specimens known from Triassic strata in Argentina. Although the sphenodontian and cynodont-dominated fauna of Quebrada del Barro is akin to that of the Faxinal del Sotorno assemblage of the Brazilian Caturrita Formation, the fauna of the Faxinal del Sotorno assemblage is otherwise indicative of an older part of the Triassic than the Quebrada del Barro Formation.[3]

Dinosaurs

Theropods
of the Quebrada del Barro Formation
Genus Species Material Notes Images
Lucianovenator[8] L. bonoi Several specimens including vertebrae, hip fragments, and a partial tibia A
theropod
Sauropodomorphs
of the Quebrada del Barro Formation
Taxon Species Material Notes Images

Ingentia[9]

I. prima

"cervical and dorsal vertebrae, scapula"

A

sauropod
Leyesaurus[2] L. marayensis A
sauropodomorph. Known from uppermost layers which may belong to a different unit of Hettangian (Early Jurassic) age.[3]
Sauropodomorpha sp. Complete foot and tail vertebrae Undiagnostic sauropodomorph remains originally referred to Riojasaurus[2][10]

Other
avemetatarsalians

Non-dinosaur avemetatarsalias of the Quebrada del Barro Formation
Taxon Species Material Notes Images
Dromomeron[11] D. gigas A partial femur a
lagerpetid
Pachagnathus P. benitoi Snout fragment A
raeticodactylid pterosaur[12]
Pterosauria
 sp. Partial ulna an indeterminate pterosaur[3]
Yelaphomte Y. praderioi Snout fragment A
raeticodactylid pterosaur[12]

Pseudosuchians

Pseudosuchias of the Quebrada del Barro Formation
Taxon Species Material Notes Images
"Rauisuchidae" sp. Skull fragments, osteoderms an indeterminate "rauisuchid" smaller than Fasolasuchus[3]
Crocodylomorpha sp. A specimen including a partial osteoderm and vertebrae fragments Indeterminate, possibly a "
sphenosuchid"[3]
Crocodylomorpha sp. Two incomplete specimens including osteoderms, vertebrae, and other bones a
protosuchid, possibly synonymous with Hemiprotosuchus[3]

Rhynchocephalians

Rhynchocephalians
of the Quebrada del Barro Formation
Genus Species Material Notes Images
Sphenotitan[13] S. leyesi numerous specimens (~50% of all recovered fossils)[3] an
sphenodontian

Other reptiles

Other reptiles of the Quebrada del Barro Formation
Taxon Species Material Notes Images
Archosauriformes sp. Maxilla, caudal vertebra, metatarsal, indeterminate limb bone (tibia?) Various indeterminate fragments likely belonging to
dinosauromorphs[4]
Waluchelys W. cavitesta 2 partial skeletons and carapaces an australochelyid stem-turtle[14][3]

Synapsids

Synapsids
of the Quebrada del Barro Formation
Taxon Species Material Notes Images
Tritheledontidae sp. 36 specimens, including a partial skeleton an undescribed
cynodont. May be two taxa based on two morphotypes: "long-snout" and "short-snout".[3]

References

  1. ^ Gardini et al., 2009, p.554
  2. ^
    PMID 22096511
    .
  3. ^
    S2CID 131662341
    .
  4. ^
    ISSN 0895-9811
    .
  5. ^ "Uac wants a provincial park in the cradle of Ingenia Prima". Naaju. Retrieved 2018-07-15.
  6. ^
    S2CID 131239254
    .
  7. ISBN 0-520-24209-2
    .
  8. ^ Ricardo N. Martínez; Cecilia Apaldetti (2017). "A late Norian-Rhaetian coelophysid neotheropod (Dinosauria, Saurischia) from the Quebrada del Barro Formation, northwestern Argentina". Ameghiniana. in press. doi:10.5710/AMGH.09.04.2017.3065.
  9. S2CID 49669597
    .
  10. ISBN 0-7853-0443-6
    .
  11. S2CID 131613066
    .
  12. ^
    S2CID 247494547
    .
  13. PMID 24132307
    .
  14. S2CID 225515560
    .

Bibliography
Retrieved from "https://en.wikipedia.org/w/index.php?title=Quebrada_del_Barro_Formation&oldid=1222480929"