{{Short description|Geologic formation in Argentina}} {{Infobox rockunit | name = Quebrada del Barro Formation | image = | caption = | type = [[Geological formation]] | period = Norian | age = [[Norian]] | prilithology = [[Sandstone]] | otherlithology = [[Siltstone]] | namedfor = | namedby = | region = [[San Juan Province, Argentina|San Juan Province]] | country = Argentina | coordinates = {{coord|31.9|S|67.2|W|display=inline,title}} | paleocoordinates = {{coord|40.8|S|30.0|W|display=inline}} | unitof = [[Marayes Group]] | subunits = | underlies = [[Los Riscos Formation]] | overlies = [[Carrizal Formation]] | thickness = | extent = [[Marayes-El Carrizal Basin]] | area = | map = {{Location map+ | Argentina | relief = 1 | width = 250 | float = center | places = {{Location map~ | Argentina | lat_deg = -31.9 | lon_deg = -67.2 | mark = Pink ff0080 pog.svg | marksize = 12 }} }} | map_caption = }} The '''Quebrada del Barro Formation''' is a geological [[Formation (geology)|formation]] of the [[Marayes-El Carrizal Basin]] in [[San Juan Province, Argentina|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]].<ref name=Gardini2009_p554>Gardini et al., 2009, p.554</ref><ref name="Leyesaurus" /><ref name="Martinez2015" /><ref name="Archosauriformes2016" /> 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 [[Sauropoda|sauropods]].<ref>{{Cite news|url=http://naaju.com/argentina/uac-wants-a-provincial-park-in-the-cradle-of-ingenia-prima/|title=Uac wants a provincial park in the cradle of Ingenia Prima|work=Naaju|access-date=2018-07-15|language=en-US|archive-date=2023-11-26|archive-url=https://web.archive.org/web/20231126223425/https://naaju.com/argentina/uac-wants-a-provincial-park-in-the-cradle-of-ingenia-prima/|url-status=dead}}</ref>
== Sedimentology == The Quebrada del Barro Formation formed within a [[Rift|rift basin]] during a period of renewed fracturing. It encompasses {{convert|600|to|1400|m|ft}} of red [[sandstone]]s, fine [[Conglomerate (geology)|conglomerates]], and [[diamictite]]s.<ref name="Martinez2015" /> 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 [[Semi-arid climate|semiarid]] floodplain deposited by [[mudflow]]s and discharging in [[Heterolithic bedding|heterolithic]] [[terminal splays]].<ref name=":0">{{Cite journal|last1=Colombi|first1=Carina E.|last2=Martínez|first2=Ricardo N.|last3=Correa|first3=Gustavo|last4=Fernández|first4=Eliana|last5=Malnis|first5=Paula Santi|last6=Praderio|first6=Angel|last7=Apaldetti|first7=Cecilia|last8=Abelín|first8=Diego|last9=Alcober|first9=Oscar|last10=Aguilar-Cameo|first10=Andrea|title=First Argentine Microfossil Bonebed from the Upper Triassic Marayes—El Carrizal Basin, San Juan Province|date=October 2015|url=https://www.researchgate.net/publication/283222785|journal=PALAIOS|language=en|volume=30|issue=10|pages=743–757|doi=10.2110/palo.2014.055|bibcode=2015Palai..30..743C |s2cid=131239254|issn=0883-1351|hdl=11336/4899|hdl-access=free}}</ref>
== Fossil content == The fauna of Quebrada del Barro is similar to that of the neighboring [[Los Colorados Formation]] which is considered to be from the [[Norian]] stage of the Late Triassic.<ref name="triassicdistribution">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}}.</ref> Both formations preserve fossils from groups such as [[Sauropodomorpha|sauropodomorph]] [[dinosaur]]s, [[cynodont]]s, and [[testudinata]]ns. However, Quebrada del Barro is more abundant in [[Rhynchocephalia|sphenodontians]] (''[[Sphenotitan]]''), [[Tritheledontidae|tritheledontid]] cynodonts, and [[Coelophysoidea|coelophysoid]] dinosaurs (''[[Lucianovenator]]''), while sauropodomorphs are somewhat less common and [[aetosaur]]s are completely absent, in contrast to the Los Colorados Formation.<ref name="Martinez2015" /> Sphenodontians and cynodonts are also abundant in microfossil assemblages.<ref name=":0" /> 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 [[Brazil]]ian [[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.<ref name="Martinez2015" />
=== Dinosaurs === {| class="wikitable" align="center" |- ! colspan="7" align="center" |'''[[Theropod]]s of the Quebrada del Barro Formation''' |- ! Genus ! Species ! width="20%"| Material ! width="30%"| Notes ! Images |- | ''[[Lucianovenator]]''<ref>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]].</ref> | ''L. bonoi'' | Several specimens including vertebrae, hip fragments, and a partial tibia | A [[coelophysid]] [[theropod]] | [[File:Lucianovenator restoration.jpg|center|150px]] |- |}
{| class="wikitable" align="center" |- ! colspan="7" align="center" |'''[[Sauropodomorph]]s of the Quebrada del Barro Formation''' |- ! Taxon ! Species ! width="20%"| Material ! width="30%"| Notes ! Images |- | ''[[Ingentia]]''<ref name="apaldetti2018">{{Cite journal |last1=Apaldetti |last2=Martínez |first2=Ricardo N. |last3=Cerda |first3=Ignatio A. |last4=Pol |first4=Diego |last5=Alcober |first5=Oscar |year=2018 |title=An early trend towards gigantism in Triassic sauropodomorph dinosaurs |journal=Nature Ecology & Evolution |volume=2 |issue=8 |pages=1227–1232 |doi=10.1038/s41559-018-0599-y|pmid=29988169 |bibcode=2018NatEE...2.1227A |hdl=11336/89332 |s2cid=49669597 |hdl-access=free }}</ref> | ''I. prima'' | "cervical and dorsal vertebrae, scapula" | A [[Lessemsauridae|lessemsaurid]] [[sauropod]] | |- | ''[[Leyesaurus]]''<ref name=Leyesaurus>{{cite journal |year=2011 |title=A New Basal Sauropodomorph (Dinosauria: Saurischia) from Quebrada del Barro Formation (Marayes-El Carrizal Basin), Northwestern Argentina |journal=PLOS ONE |volume=6 |issue=11 |article-number=e26964 |doi=10.1371/journal.pone.0026964 |author=Cecilia Apaldetti |author2=Ricardo N. Martinez |author3=Oscar A. Alcober |author4=Diego Pol |editor1-last=Claessens |editor1-first=Leon |pmid=22096511 |pmc=3212523 |doi-access=free |bibcode=2011PLoSO...626964A }}</ref> | ''L. marayensis'' | | A [[Massospondylidae|massospondylid]] [[sauropodomorph]]. Known from uppermost layers which may belong to a different unit of [[Hettangian]] ([[Early Jurassic]]) age.<ref name="Martinez2015" /> | [[File:Leyesaurus skull in dorsal view.png|center|100px]] |- | [[Sauropodomorpha]] | ''sp.'' | Complete foot and tail vertebrae | Undiagnostic sauropodomorph remains originally referred to ''[[Riojasaurus]]''<ref name=Leyesaurus/><ref name="ageofdinosaursriojasaurus">"Riojasaurus." In: Dodson, Peter & Britt, Brooks & Carpenter, Kenneth & Forster, Catherine A. & Gillette, David D. & Norell, Mark A. & Olshevsky, George & Parrish, J. Michael & Weishampel, David B. ''The Age of Dinosaurs''. Publications International, LTD. p. 41. {{ISBN|0-7853-0443-6}}.</ref> | |- |}
=== Other [[avemetatarsalian]]s === {| class="wikitable" align="center" |- ! colspan="7" align="center" | '''Non-dinosaur [[avemetatarsalia]]s of the Quebrada del Barro Formation''' |- ! Taxon ! Species ! width="20%"| Material ! width="30%"| Notes ! Images |- | ''[[Dromomeron]]''<ref>{{Cite journal|author1=Ricardo N. Martínez |author2=Cecilia Apaldetti |author3=Gustavo A. Correa |author4=Diego Abelín |year=2016 |title=A Norian lagerpetid dinosauromorph from the Quebrada del Barro Formation, northwestern Argentina |journal=Ameghiniana |volume=53 |issue=1 |pages=1–13 |doi=10.5710/AMGH.21.06.2015.2894 |s2cid=131613066 }}</ref> | ''D. gigas'' | A partial femur | a [[lagerpetid]] | [[File:Dromomeron BW.jpg|center|100px]] |- | ''[[Pachagnathus]]'' | ''P. benitoi'' | Snout fragment | A [[raeticodactylid]] [[pterosaur]]<ref name=":1">{{Cite journal |last1=Martínez |first1=Ricardo N. |last2=Andres |first2=Brian |last3=Apaldetti |first3=Cecilia |last4=Cerda |first4=Ignacio A. |date=March 2022 |title=The dawn of the flying reptiles: first Triassic record in the southern hemisphere |url=https://onlinelibrary.wiley.com/doi/10.1002/spp2.1424 |journal=Papers in Palaeontology |volume=8 |issue=2 |doi=10.1002/spp2.1424 |bibcode=2022PPal....8E1424M |s2cid=247494547 |issn=2056-2799|url-access=subscription }}</ref> | |- | [[Pterosauria]] | ''sp.'' | Partial ulna | an indeterminate [[pterosaur]]<ref name="Martinez2015">{{Cite journal|last1=Martínez|first1=Ricardo N.|last2=Apaldetti|first2=Cecilia|last3=Correa|first3=Gustavo|last4=Colombi|first4=Carina E.|last5=Fernández|first5=Eliana|last6=Malnis|first6=Paula Santi|last7=Praderio|first7=Angel|last8=Abelín|first8=Diego|last9=Benegas|first9=Laura G.|last10=Aguilar-Cameo|first10=Andrea|last11=Alcober|first11=Oscar A.|date=August 2015|title=A New Late Triassic Vertebrate Assemblage from Northwestern Argentina|url=https://www.researchgate.net/publication/276133829|journal=Ameghiniana|volume=52|issue=4|pages=379–390|doi=10.5710/AMGH.27.04.2015.2889|s2cid=131662341|issn=0002-7014|hdl=11336/111650|hdl-access=free}}</ref> | |- | ''[[Yelaphomte]]'' | ''Y. praderioi'' | Snout fragment | A [[raeticodactylid]] [[pterosaur]]<ref name=":1" /> | |- |}
=== Pseudosuchians === {| class="wikitable" align="center" |- ! colspan="7" align="center" | '''[[Pseudosuchia]]s of the Quebrada del Barro Formation''' |- ! Taxon ! Species ! width="20%"| Material ! width="30%"| Notes ! Images |- | "[[Rauisuchidae]]" | ''sp.'' | Skull fragments, osteoderms | an indeterminate "[[Rauisuchidae|rauisuchid]]" smaller than ''[[Fasolasuchus]]''<ref name="Martinez2015"/> | |- | [[Crocodylomorpha]] | ''sp.'' | A specimen including a partial osteoderm and vertebrae fragments | Indeterminate, possibly a "[[Sphenosuchidae|sphenosuchid]]"<ref name="Martinez2015"/> | |- | [[Crocodylomorpha]] | ''sp.'' | Two incomplete specimens including osteoderms, vertebrae, and other bones | a [[protosuchid]], possibly synonymous with ''[[Hemiprotosuchus]]''<ref name="Martinez2015"/> | |- |}
=== Rhynchocephalians === {| class="wikitable" align="center" |- ! colspan="7" align="center" | '''[[Rhynchocephalian]]s of the Quebrada del Barro Formation''' |- ! Genus ! Species ! width="20%"| Material ! width="30%"| Notes ! Images |- | ''[[Sphenotitan]]''<ref name=Sphenotitan>{{Cite journal | last1 = Martinez | first1 = R. N. | last2 = Apaldetti | first2 = C. | last3 = Colombi | first3 = C. E. | last4 = Praderio | first4 = A. | last5 = Fernandez | first5 = E. | last6 = Malnis | first6 = P. S. | last7 = Correa | first7 = G. A. | last8 = Abelin | first8 = D. | last9 = Alcober | first9 = O. | doi = 10.1098/rspb.2013.2057 | title = A new sphenodontian (Lepidosauria: Rhynchocephalia) from the Late Triassic of Argentina and the early origin of the herbivore opisthodontians | journal = Proceedings of the Royal Society B: Biological Sciences | volume = 280 | issue = 1772 | article-number = 20132057 | year = 2013 | pmid = 24132307| pmc = 3813332}}</ref> | ''S. leyesi'' | numerous specimens (~50% of all recovered fossils)<ref name="Martinez2015"/> | an [[Eilenodontinae|eilenodontine]] [[sphenodontian]] |[[File:Sphenotitan skull.svg|center|frameless]] |- |}
=== Other reptiles === {| class="wikitable" align="center" |- ! colspan="7" align="center" | '''Other reptiles of the Quebrada del Barro Formation''' |- ! Taxon ! Species ! width="20%"| Material ! width="30%"| Notes ! Images |- | [[Archosauriformes]] | ''sp.'' | Maxilla, caudal vertebra, metatarsal, indeterminate limb bone (tibia?) | Various indeterminate fragments likely belonging to [[pseudosuchian]]s or [[dinosauromorph]]s<ref name="Archosauriformes2016">{{Cite journal|last1=Gianechini|first1=Federico A.|last2=Codorniú|first2=Laura|last3=Arcucci|first3=Andrea B.|last4=Castillo Elías|first4=Gabriela|last5=Rivarola|first5=David|date=March 2016|title=Archosauriform remains from the Late Triassic of San Luis province, Argentina, Quebrada del Barro Formation, Marayes–El Carrizal Basin|url=https://www.researchgate.net/publication/288858161|journal=Journal of South American Earth Sciences|volume=66|pages=110–124|doi=10.1016/j.jsames.2015.12.012|bibcode=2016JSAES..66..110G |issn=0895-9811|hdl=11336/60591|hdl-access=free}}</ref> | |- | ''[[Waluchelys]]'' | ''W. cavitesta'' | 2 partial skeletons and carapaces | an [[australochelyid]] [[Pantestudines|stem-turtle]]<ref>{{Cite journal|last1=Sterli|first1=Juliana|last2=Martínez|first2=Ricardo N.|last3=Cerda|first3=Ignacio A.|last4=Apaldetti|first4=Cecilia|title=Appearances can be deceptive: bizarre shell microanatomy and histology in a new Triassic turtle (Testudinata) from Argentina at the dawn of turtles|url=https://onlinelibrary.wiley.com/doi/abs/10.1002/spp2.1334|journal=Papers in Palaeontology|year=2021|volume=7|issue=2|pages=1097–1132|language=en|doi=10.1002/spp2.1334|bibcode=2021PPal....7.1097S |s2cid=225515560|issn=2056-2802|url-access=subscription}}</ref><ref name="Martinez2015"/> | |- |}
=== Synapsids === {| class="wikitable" align="center" |- ! colspan="7" align="center" | '''[[Synapsid]]s of the Quebrada del Barro Formation''' |- ! Taxon ! Species ! width="20%"| Material ! width="30%"| Notes ! Images |- | [[Tritheledontidae]] | ''sp.'' | 36 specimens, including a partial skeleton | an undescribed [[Tritheledontidae|tritheledontid]] [[cynodont]]. May be two taxa based on two morphotypes: "long-snout" and "short-snout".<ref name="Martinez2015"/> | |- |}
== References == {{reflist}}
=== Bibliography === * {{cite journal |last1=Gardini |first1=Carlos |last2=Rivarola |first2=David |last3=Agüera |first3=Maximiliano |last4=Candela |first4=Gerónimo |year=2009 |title=Estructura de la región Sierra de Guayaguas-Marayes, Provincias de San Juan y San Luis |url=http://www.scielo.org.ar/pdf/raga/v65n3/v65n3a12.pdf |journal=[[Revista de la Asociación Geológica Argentina]] |volume=65 |pages=551–565 |access-date=2018-09-08}}
[[Category:Geologic formations of Argentina]] [[Category:Triassic System of South America]] [[Category:Late Triassic South America]] [[Category:Triassic Argentina]] [[Category:Norian Stage]] [[Category:Sandstone formations]] [[Category:Siltstone formations of Argentina]] [[Category:Alluvial deposits]] [[Category:Fluvial deposits]] [[Category:Fossiliferous stratigraphic units of South America]] [[Category:Paleontology in Argentina]] [[Category:Geology of San Juan Province, Argentina]]