View source for Los Colorados Formation

{{other uses|Colorado Formation (disambiguation){{!}}Colorado Formation}}
{{Infobox rockunit
| name           = Los Colorados Formation
| image          = Los Colorados, La Rioja, Argentina.jpg
| caption        = Los Colorados massif, La Rioja Province, Argentina
| type           = [[Geological formation]]
| period         = Norian
| age            = [[Norian]]<br />~{{fossil range|227|213}}
| prilithology   = [[Sandstone]], [[siltstone]], [[mudstone]]
| otherlithology = [[Conglomerate (geology)|Conglomerate]], [[gypsum]]
| namedfor       = [[Los Colorados Massif]]
| namedby        =
| region         = [[San Juan Province, Argentina|San Juan Province]]<br />[[La Rioja Province, Argentina|La Rioja Province]]
| country        = Argentina
| coordinates    = {{coord|29.8|S|67.9|W|source:wikidata|display=inline,title}}
| paleocoordinates = {{coord|38.9|S|31.4|W|display=inline}}
| unitof         = [[Agua de la Peña Group]]
| subunits       =
| underlies      = [[Cerro Rajado Formation]]
| overlies       = [[Ischigualasto Formation]]
| thickness      = {{convert|600|m|ft|abbr=on}}
| extent         = [[Ischigualasto-Villa Unión Basin]]
| area           =
| map            = {{Location map+ | Argentina
| relief = 1
| width   = 250
| float   = center
| places  =
  {{Location map~ | Argentina
  | lat_deg = -29.8
  | lon_deg = -67.9
  | mark = Pink ff0080 pog.svg
  | marksize = 12
  }}
}}
| map_caption    =
}}
The '''Los Colorados Formation''' is a [[sedimentary]] [[geological formation|rock formation]] of the [[Ischigualasto-Villa Unión Basin]], found in the provinces of [[San Juan Province, Argentina|San Juan]] and [[La Rioja Province (Argentina)|La Rioja]] in [[Argentina]]. The formation dates back to the [[Norian]] age of the [[Late Triassic]].

The up to {{convert|600|m|ft}} thick formation comprises [[sandstone]]s, [[siltstone]]s, [[mudstone]]s and [[Conglomerate (geology)|conglomerates]] with [[gypsum]] layers deposited in a [[fluvial]] to [[lacustrine]] [[depositional environment|environment]]. The formation is the uppermost stratigraphic unit of the [[Agua de la Peña Group]], overlying the [[Lagerstätte]] of the [[Ischigualasto Formation]]. Los Colorados Formation is partly covered by the [[Cretaceous]] [[Cerro Rajado Formation]], separated by an [[unconformity]].

The formation is known for its [[fossil]]s of early [[dinosaur]]s, including the [[coelophysoid]] ''[[Zupaysaurus]]'' and the "[[prosauropoda|prosauropods]]" ''[[Coloradisaurus]]'', ''[[Lessemsaurus]]'', and ''[[Riojasaurus]]''.<ref name="triassicdistribution">Weishampel et al., 2004, pp.527-528</ref> Magnetostratigraphic analysis suggests that the Los Colorados Formation was deposited between 227 and 213 million years ago.<ref name=Kent2014_p7959>Kent et al, 2014, p.7959</ref>

== Description ==
[[File:Ischigualasto-Villa Unión Basin Map detail.png|right|250px|thumb|Extent of the formation in the Ischigualasto-Villa Unión Basin]]
Los Colorados Formation is a unit with an approximate thickness of {{convert|600|m|ft}} of the [[Agua de la Peña Group]] in the [[Ischigualasto-Villa Unión Basin]], where it is exposed in the [[Ischigualasto Provincial Park]], a [[World Heritage Site]] in Argentina. The formation gradually overlies the [[Ischigualasto Formation]] and is unconformably overlain by the [[Cretaceous]] [[Cerro Rajado Formation]]. The formation comprises red-colored, fine- to medium-grain–size [[sandstone]]s together with [[siltstone]]s and ancillary [[floodplain]] [[mudstone]]s with early [[calcisol]] development. The formation was deposited in a [[fluvial]] to [[lacustrine]] [[depositional environment|environment]].<ref name=Kent2014_p7959/>

==Fossil content==
===Anapsids===
{| class="wikitable" align="center"
|-
! colspan="7" align="center" | '''[[Anapsid]]s of Los Colorados Formation'''
|-
! Genus
! Species
! Location
! Material
! Notes
! Images
|-
|
''[[Palaeochersis]]''
|
''P. talampayensis''
|
|
| align=center | <ref name=Arcucci2004_p561>Arcucci et al., 2004, p.561</ref><ref>[https://paleobiodb.org/classic/displayCollResults?collection_no=105693 2 km NE of La Esquina] at [[Fossilworks]].org</ref>
|
|-
|}

===Synapsids===
{| class="wikitable" align="center"
|-
! colspan="6" align="center" | '''[[Synapsid]]s of Los Colorados Formation'''
|-
! Genus
! Species
! Location
! Material
! Notes
! Images
|-
| ''[[Chaliminia]]''
| ''C. musteloides''
|
|
| align="center" | <ref name="Arcucci2004_p561" />
|
|-
|''[[Jachaleria]]''
|''J. colorata''
|
| A skull and complete jaws.
| A Kanemyeriidae [[dicynodont]].
|[[File:Jachaleria candelariensis 2.jpg|frameless]]
|-
|''[[Tessellatia]]''
|''T. bonapartei''
|
| A partial skull, including the snout, orbital region, and lower jaws.
| A cynodont.<ref>{{cite journal|last1=Gaetano |first1=L. C. |last2=Abdala |first2=F. |last3=Seoane |first3=F. D. |last4=Tartaglione |first4=A. |last5=Schulz |first5=M. |last6=Otero |first6=A. |last7=Leardi |first7=J. M. |last8=Apaldetti |first8=C. |last9=Krapovickas |first9=V. |last10=Steimbach |first10=E. |title=A new cynodont from the Upper Triassic Los Colorados Formation (Argentina, South America) reveals a novel paleobiogeographic context for mammalian ancestors |year=2022 |journal=Scientific Reports |volume=12 |issue=1 |pages=Article number 6451 |doi=10.1038/s41598-022-10486-4 |pmid=35468982 |pmc=9038739 |bibcode=2022NatSR..12.6451G | doi-access = free }}</ref>
|
|-
|}

===Archosauromorphs===
{| class="wikitable" align="center"
|-
! colspan="6" align="center" | '''[[Archosauromorphs]] of Los Colorados Formation'''
|-
! Genus
! Species
! Location
! Material
! Notes
! Images
|-
| ''[[Fasolasuchus]]''
| ''F. tenax''
| La Rioja Province
| A fragmented skull and jaws.
| A giant [[loricatan]] [[Pseudosuchian]].<ref name="triassicdistribution" /><ref name=Arcucci2004_p561/>
| 
|-
| ''[[Neoaetosauroides]]''
| ''N. engaeus''
| Quebrada de los Jachaleros, El Salto (San Juan)
|
| An [[aetosaur]].<ref name=Arcucci2004_p561/>
| [[File:Neoaetosauroides.jpg|center|151x151px]]
|-
|''[[Riojasuchus]]''
| ''R. tenuisceps''
|
|
| An [[ornithosuchid]].<ref name=Arcucci2004_p561/><ref name=VonBaczko2016_p4>Von Baczko & Desojo, 2016, p.4</ref>
| [[File:Riojasuchus BW.jpg|center|150px]]
|-
|}

====Crocodylomorpha====
{| class="wikitable" align="center"
|-
! colspan="6" align="center" | '''[[Crocodylomorph]]s of Los Colorados Formation'''
|-
! Genus
! Species
! Location
! Material
! Notes
! Images
|-
| ''[[Coloradisuchus]]''
|''C. abelini''
| La Rioja Province
|
| align=center | <ref name=Martinez2018_p1>Martínez et al., 2018, p.1</ref>
|
|-
| ''[[Hemiprotosuchus]]''
| ''H. leali''
| Quebrada de los Jachaleros, El Salto (San Juan)
|
| align=center | <ref name=Arcucci2004_p561/><ref name=Martinez2018_p1/>
|
|-
| ''[[Pseudhesperosuchus]]''
|''P. jachaleri''
| Quebrada de los Jachaleros, El Salto (San Juan)
|
| align=center | <ref name=Arcucci2004_p561/>
| [[File:Pseudhesperosuchus.jpg|center|150px]]
|-
|}

====Dinosaurs====
Indeterminate theropod remains present in the [[Provincia de la Rioja]].<ref name="triassicdistribution" />

{| class="wikitable" align="center"
|-
! colspan="6" align="center" | '''[[Dinosaur]]s of Los Colorados Formation'''
|-
! Genus
! Species
! Location
! Material
! Notes
! Images
|-
| ''[[Coloradisaurus]]''
| ''C. brevis''
| La Rioja Province<ref name="triassicdistribution" />
| "Skull, adult"<ref name=Arcucci2004_p561/><ref name="table-12-1-234">"Table 12.1," in Weishampel ''et al.'', 2004. p.234</ref>
| A massospondylid sauropodomorph.
|[[Image: Coloradisaurus_skull_reconstruction.png|200px|center]]
|-
| ''[[Lessemsaurus]]''
| ''L. sauropoides''
| La Rioja Province<ref name="triassicdistribution" />
| "Partial cervical, dorsal, and sacral vertebrae, adult."<ref name="table-12-1-234"/>
| A [[sauropodiform]].
| [[File:Lessemsaurus_Senckenberg.jpg|center|150px]]
|-
| [[Prosauropoda]]
| Indeterminate
| La Rioja & San Juan Provinces
| Includes ''[[Strenusaurus]] procerus''.<ref name="triassicdistribution" /> "Dorsals, caudals, partial fore- and hindlimb."<ref name="table-12-1-237">"Table 12.1," in Weishampel, ''et al.'', 2004. Page 237.</ref>
| 
|
|-
|''[[Powellvenator]]''
| ''P. podocitus
| Ischigualasto-Villa Unión Basin
| Known from previously undescribed partial hindlimbs
| A coelophysoid.
|
|-
| ''[[Riojasaurus]]''
| ''R. incertus''
| La Rioja Province
|
| A [[sauropodomorph]].<ref name=Ezcurra2017>Ezcurra, 2017</ref><ref name=Arcucci2004_p561/><ref name="triassicdistribution" />
| [[File:Riojasaurus NT.jpg|center|150px]]
|-
| ''[[Zupaysaurus]]''
| ''Z. rougieri''
| La Rioja Province
|
| An early theropod.<ref name=Arcucci2004_p561/><ref name="triassicdistribution" />
| [[File:Zupaysaurus.jpg|center|150px]]
|-
|}

===Ichnofossils===
* ''[[Brachychirotherium|cf. Brachychirotherium sp.]]''<ref>[https://paleobiodb.org/classic/displayCollResults?collection_no=48723 Río de los Tarros tracksite] at [[Fossilworks]].org</ref>
* ''[[Chirotherium|Chirotherium sp.]]''<ref name=Leonardi1994_p25>Leonardi, 1994, p.25</ref><ref>[https://paleobiodb.org/classic/displayCollResults?collection_no=85569 Leonardi locality 15] at [[Fossilworks]].org</ref>

== See also ==
* [[List of dinosaur-bearing rock formations]]
* [[Quebrada del Barro Formation]], contemporaneous fossiliferous formation of the [[Marayel-El Carrizal Basin]] just southeast of the Ischigualasto-Villa Unión Basin
* [[Caturrita Formation]], contempeoraneous fossiliferous formation of the [[Paraná Basin]], southeastern Brazil
* [[Chinle Formation]], contemporaneous fossiliferous formation of Arizona
* [[Elliot Formation]], contemporaneous fossiliferous formation of the [[Karoo Basin]], South Africa
* [[Fremouw Formation]], contemporaneous fossiliferous formation of Antarctica

== References ==
{{reflist|30em}}

=== Bibliography ===
* {{citation |last1=Arcucci |first1=A.B. |last2=Marsicano |first2=C.A. |last3=Caselli |first3=A.T. |year=2004 |title=Tetrapod association and palaeoenvironment of the Los Colorados Formation (Argentina): a significant sample from western Gondwana at the end of the Triassic |url=https://www.researchgate.net/publication/40663123 |journal=[[Geobios]] |volume=37 |issue=5 |pages=557–568 |doi=10.1016/j.geobios.2003.04.008 |bibcode=2004Geobi..37..557A |hdl=11336/97772 |accessdate=2019-03-28|hdl-access=free }}
* {{citation |last1=Von Baczko |first1=Maria Belén |last2=Desojo |first2=Julia Brenda |year=2016 |title=Cranial Anatomy and Palaeoneurology of the Archosaur Riojasuchus tenuisceps from the Los Colorados Formation, La Rioja, Argentina |journal=[[PLoS ONE]] |volume=11 |issue=2 |pages=1–30 |doi=10.1371/journal.pone.0148575 |doi-access=free |pmid=26849433 |pmc=4743959 |bibcode=2016PLoSO..1148575V }}
* {{citation |last=Ezcurra |first=Martín D |year=2017 |title=A new early coelophysoid neotheropod from the Late Triassic of northwestern Argentina |url=http://www.ameghiniana.org.ar/index.php/ameghiniana/article/view/3100 |journal=[[Ameghiniana]] |volume=54 |issue=5 |pages=Abstract |doi=10.5710/AMGH.04.08.2017.3100 |accessdate=2019-03-26|hdl=11336/56719 |hdl-access=free }}
* {{citation |last1=Kent |first1=Dennis V. |last2=Santi Malnis |first2=Paula |last3=Colombi |first3=Carina E. |last4=Alcober |first4=Oscar A. |last5=Martínez |first5=Ricardo N. |year=2014 |title=Age constraints on the dispersal of dinosaurs in the Late Triassic from magnetochronology of the Los Colorados Formation (Argentina) |journal=[[Proceedings of the National Academy of Sciences]] |volume=111 |issue=22 |pages=7958–7963 |doi=10.1073/pnas.1402369111 |doi-access=free |pmid=24843149 |pmc=4050597 |bibcode=2014PNAS..111.7958K }}
* {{citation |last=Leonardi |first=Giuseppe |year=1994 |title=Annotated Atlas of South America Tetrapod Footprints (Devonian to Holocene) with an appendix on Mexico and Central America |url=https://www.researchgate.net/publication/309643073 |publisher=Ministerio de Minas e Energia - Companhia de Pesquisa de Recursos Minerais, Geological Service of Brazil |pages=1–248 |accessdate=2019-03-25}}
* {{citation |last1=Martínez |first1=Ricardo N. |last2=Alcober |first2=Oscar A. |last3=Pol |first3=Diego |year=2018 |title=A new protosuchid crocodyliform (Pseudosuchia, Crocodylomorpha) from the Norian Los Colorados Formation, northwestern Argentina |url=https://www.tandfonline.com/doi/abs/10.1080/02724634.2018.1491047?journalCode=ujvp20 |journal=[[Journal of Vertebrate Paleontology]] |volume=38 |issue=4 |pages=1–12 |doi=10.1080/02724634.2018.1491047 |accessdate=2019-03-28|hdl=11336/98862 |hdl-access=free }}
* {{citation |last1=Weishampel |first1=David B. |author2-link=Peter Dodson |last2=Dodson |first2=Peter |author3-link=Halszka Osmólska |last3=Osmólska |first3=Halszka |year=2004 |title=The Dinosauria, 2nd edition |url=https://books.google.com/books?id=vtZFDb_iw40C |publisher=Berkeley: University of California Press |pages=1–880 |accessdate=2019-02-21 |isbn=0-520-24209-2 |author1-link=David B. Weishampel }}

== Further reading ==
{{commons category|Los Colorados Formation}}
* A. B. Arcucci and R. A. Coria. 2003. A new Triassic carnivorous dinosaur from Argentina. Ameghiniana 40(2):217-228
* J. F. Bonaparte. 1999. Evolución de las vértebras presacras en Sauropodomorpha [Evolution of the presacral vertebrae in Sauropodomorpha]. Ameghiniana 36(2):115-187
* J. F. Bonaparte and J. A. Pumares. 1995. Notas sobre el primer craneo de ''Riojasaurus incertus'' (Dinosauria, Prosauropoda, Melanorosauridae) del Triasico Superior de La Rioja, Argentina [Notes on the first skull and jaws of ''Riojasaurus incertus'' (Dinosauria, Prosauropoda, Melanorosauridae), Late Triassic of La Rioja, Argentina]. Ameghiniana 32(4):341-349
* J. F. Bonaparte. 1981. Descripción de "''Fasolasuchus tenax''" y su significado en la sistematica y evolución de los thecodontia. Revista del Museo Argentino de Ciencias Naturales "Bernardino Rivadavia" 3(2):55-101
* J. F. Bonaparte. 1978. ''Coloradia brevis'' n. g. et n. sp. (Saurischia–Prosauropoda), dinosaurio Plateosauridae de la Formacion Los Colorados, Triasico Superior de La Rioja, Argentina [''Coloradia brevis'' n. g. et n. sp. (Saurischia–Prosauropoda), a plateosaurid from the Upper Triassic Los Colorados Formation of La Rioja, Argentina]. Ameghiniana 15(3-4):327-332
* J. F. Bonaparte. 1971. Los tetrapodos del sector superior de la Formacion Los Colorados, La Rioja, Argentina (Triásico Superior) [The tetrapods of the upper part of the Los Colorados Formation, La Rioja, Argentina (Upper Triassic)]. Opera Lilloana 22:1-183
* J. F. Bonaparte. 1969. Dos nuevas "faunas" de reptiles triasicos de Argentina [Two new reptilian "faunas" of the Argentine Triassic]. Gondwana Stratigraphy (IUGS Symposium, Buenos Aires) 2:283-306
* J. B. Desojo and A. M. Baez. 2007. Cranial morphology of the Late Triassic South American archosaur ''Neoaetosauroides engaeus'': evidence for aetosaurian diversity. Palaeontology 50:267-276
* J. B. Desojo and A. M. Baez. 2005. El esqueleto postcraneano de ''Neoaetosauroides'' (Archosauria: Aetosauria) del Triásico Superior del centro-oeste de Argentina. Ameghiniana 42:115-126
* M. D. Ezcurra and C. Apaldetti. 2012. A robust sauropodomorph specimen from the Upper Triassic of Argentina and insights on the diversity of the Los Colorados Formation. Proceedings of the Geologists' Association 123:155-164
* A. G. Martinelli and G. W. Rougier. 2007. On ''Chaliminia musteloides'' (Eucynodontia: Tritheledontidae) from the Late Triassic of Argentina, and a phylogeny of Ictidosauria. Journal of Vertebrate Paleontology 27:442-460
* G. W. Rougier, M. S. de la Fuente, and A. B. Arcucci. 1995. Late Triassic turtles from South America. Science 268:855-858

[[Category:Los Colorados Formation| ]]
[[Category:Late Triassic South America]]
[[Category:Norian Stage]]
[[Category:Sandstone formations]]
[[Category:Mudstone formations]]
[[Category:Siltstone formations]]
[[Category:Fluvial deposits]]
[[Category:Lacustrine deposits]]
[[Category:Geology of La Rioja Province, Argentina]]
[[Category:Geology of San Juan Province, Argentina]]