Editing Unaysaurus

{{Short description|Extinct genus of dinosaurs}}
{{Automatic taxobox
| fossil_range = [[Late Triassic]], {{Fossil range|225.42}}
| image = Skeletal reconstruction of Unaysaurus tolentinoi.png
| image_upright = 1.1
| image_caption = Skeletal diagram showing known remains
| display_parents = 3
| taxon = Unaysaurus
| authority = Leal ''et al.'', 2004
| type_species = {{extinct}}'''''Unaysaurus tolentinoi'''''
| type_species_authority = Leal ''et al.'', 2004
}}

'''''Unaysaurus''''' is a [[genus]] of [[unaysauridae|unaysaurid]] [[sauropodomorpha|sauropodomorph]] herbivore [[dinosaur]]. Discovered in southern [[Brazil]], in the [[geopark]] of Paleorrota, in 1998, and announced in a press conference on Thursday, December 3, 2004, it is one of the oldest dinosaurs known. It is closely related to [[plateosauridae|plateosaurid]] dinosaurs found in [[Germany]], which indicates that it was relatively easy for [[species]] to spread across the giant landmass of the time, the [[supercontinent]] of [[Pangaea]].<ref name="leal"/>

The [[fossil]]s of ''Unaysaurus'' are well preserved. They consist of an almost complete [[skull]], complete with a [[mandible|lower jaw]], and partial skeleton with many of the bones still connected to each other in their natural positions. It is one of the most complete dinosaur skeletons (including complete skull) ever recovered in Brazil.

== Discovery and naming ==
[[File:Unaysaurus.jpg|thumb|left|Life restoration]]
''Unaysaurus'' was found in the southern Brazilian state of [[Rio Grande do Sul]], near the city of [[Santa Maria, Rio Grande do Sul|Santa Maria]]. It was recovered from the red beds of the [[Caturrita Formation]], which is the geologic formation where similarly old dinosaurs like ''[[Saturnalia (dinosaur)|Saturnalia]]'' have been found. The oldest dinosaurs in the world are from here and nearby in [[Argentina]] (like the ''[[Eoraptor]]''), which suggests that the first dinosaurs may have originated in the area.

In 2004, Luciano A. Leal, Sergio A. K. Azevodo, Alexander W. A. Kellner, and Átila A. S. da Rosa [[Species description|described]] ''Unaysaurus tolentinoi'' as a new genus and species on the basis of the [[holotype]] specimen UFSM 11069. The [[Genus|generic name]], "''Unaysaurus''", comes from the word ''{{lang|tup|unay}}'' (u-na-hee), meaning "black water" in the local [[Tupian languages|Tupi]] language, which in turn refers to ''Agua Negra'' (also "black water"), the [[Portuguese language|Portuguese]] name for the region where the fossils were found. The [[Specific name (zoology)|specific name]], "''tolentinoi''" honors Tolentino Marafiga, who discovered the fossils by the side of a road in 1998.<ref name="leal"/>

==Description==
[[File:Unaysaurus Scale.svg|thumb|right|Size of the holotype specimen compared to a human]]
Like most early dinosaurs, ''Unaysaurus'' was relatively small, and walked on [[biped|two legs]]. It was only {{convert|2.5|m|ft|abbr=off|sp=us}} long, {{convert|70 to 80|cm|ft|sp=us}} tall, and weighed about {{convert|70|kg|lb}}).

In 2023, Müller and colleagues described the remains of a juvenile specimen of ''Unaysaurus'' that was found associated with the holotype. The bones, including partial vertebrae and various foot material, are similarly proportioned to the bones of the holotype.<ref>{{Cite journal |last1=Müller |first1=Rodrigo T. |last2=Garcia |first2=Maurício S. |last3=Bem |first3=Fabiula P. |last4=Damke |first4=Lísie V. S. |last5=Fonseca |first5=André O. |last6=Da-Rosa |first6=Átila A. S. |date=2023-07-06 |title=On a skeletally immature individual of ''Unaysaurus tolentinoi'' (Dinosauria: Sauropodomorpha) from the upper Triassic of southern Brazil |journal=The Anatomical Record |volume=307 |issue=4 |pages=1071–1083 |language=en |doi=10.1002/ar.25285 |pmid=37409690 |issn=1932-8486}}</ref>

== Classification ==
Upon its description, ''Unaysaurus'' was assigned to the [[Plateosauridae]]. Under this assignment, the closest relative of ''Unaysaurus'' was, counter intuitively, not from [[South America]], but rather ''[[Plateosaurus]]'', which lived about 210&nbsp;million years ago in [[Germany]].<ref name="leal"/> However, in 2018, ''Unaysaurus'' was found to belong to the newly erected clade [[Unaysauridae]], alongside ''[[Macrocollum]]'' and ''[[Jaklapallisaurus]]'', the former of which was from [[Brazil]].<ref>{{cite journal |author1=Rodrigo Temp Müller |author2=Max Cardoso Langer |author3=Sérgio Dias-da-Silva |year=2018 |title=An exceptionally preserved association of complete dinosaur skeletons reveals the oldest long-necked sauropodomorphs |journal=Biology Letters |volume=14 |issue=11 |pages=20180633 |doi=10.1098/rsbl.2018.0633 |pmid=30463923 |pmc=6283919}}</ref>

== Paleoecology ==

''Unaysaurus'' lived between about 225 to 200&nbsp;[[million years ago]], in the [[Carnian]] or Norian [[faunal stage|age]] of the late [[Triassic]] [[geologic period|period]]. It was found in the south of Brazil, which at the time was connected to northwest [[Africa]]. The whole world was united into the great supercontinent of Pangaea, which was just starting to divide into [[Laurasia]] in the north, and [[Gondwana]] in the south.<ref name="leal"/> A U-Pb ([[Uranium]] decay) dating found that the Caturrita Formation dated around 225.42 million years ago, putting it less than 10 million years younger than the [[Santa Maria Formation|Santa Maria]] and [[Ischigualasto Formation]]s, from where the earliest dinosaurs are known.<ref name=langer18>{{cite journal|last1=Langer|first1=M.C.|last2=Ramezani|first2=J.|last3=Da Rosa|first3=Á.A.S.|year=2018|title=U-Pb age constraints on dinosaur rise from south Brazil|journal=Gondwana Research|volume=X|issue=18|doi=10.1016/j.gr.2018.01.005|pages=133–140|bibcode=2018GondR..57..133L }}</ref>

The [[Caturrita Formation]] has uncovered a wide variety of fauna, although the formation is also referred to as the upper portion of the [[Santa Maria Formation|Santa Maria]] 2 Sequence. Multiple [[dinosauriformes|dinosauriforms]] are represented in the rock of the formation, including the [[Silesauridae|silesaur]] ''[[Sacisaurus|Sacisaurus agudoensis]]'', and the coeval [[sauropodomorpha|sauropodomorph]] ''[[Guaibasaurus|Guaibasaurus candelariensis]]'',<ref name="soares"/> all of which are not found anywhere else.<ref name="leal"/> The 
[[dicynodont]] ''[[Jachaleria|Jachaleria candelariensis]]'', an unclassified [[phytosaur]], and isolated teeth of archosaur origin can also be unearthed in the formation. A single [[stereospondyl]] amphibian is known from the formation, but has not yet been identified specifically.<ref name="soares"/>

An extremely rich amount of small [[tetrapod]]s have been recovered from the Caturrita Formation, which is quite surprising. They measure less than {{convert|15|cm|in|abbr=on}} long. Species preserved are the [[procolophonidae|procolophonid]] ''[[Soturnia caliodon]]'', the [[lepidosaur]] ''[[Cargninia|Cargninia enigmatica]]'', the [[sphenodontid]] ''[[Clevosaurus|Clevosaurus brasiliensis]]'', and some small [[therapsid]]s coexisting with ''[[Faxinalipterus minima]]'', a putative pterosaur. The therapsids include ''[[Riograndia guaibensis]]'', ''[[Brasilodon quadrangularis]]'', and ''[[Irajatherium|Irajatherium hernandezi]]'' .<ref name="soares"/>

== References ==
{{Reflist|refs=
<ref name="leal">{{cite journal | last1 = Leal | first1 = L.A. | authorlink1 = Luciano Leal | last2 = Azevodo | first2 = S.A.K. | authorlink2 = Sergio Azevodo | last3 = Kellner | first3 = A.A.W. | authorlink3 = Alexander Kellner | last4 = da Rosa | first4 = A.A.S. | authorlink4 = Átila da Rosa | year = 2004 | title = A new early dinosaur (Sauropodomorpha) from the Caturrita Formation (Late Triassic), Paraná Basin, Brazil | journal = Zootaxa | volume = 690 | pages = 1–24 | doi = 10.11646/zootaxa.690.1.1 | url = https://www.academia.edu/5324333 }}</ref>
<ref name = "soares">{{cite journal | last1 = Soares | first1 = M.B. | authorlink1 = Marina Soares | last2 = Schultz | first2 = C.L. | authorlink2 = Cesar Schultz | last3 = Horn | first3 = B.L.D. | authorlink3 = Bruno Horn | year = 2011 | title = New information on ''Riograndia guaibensis'' Bonaparte, Ferigolo & Ribeiro, 2001 (Eucynodontia, Tritheledontidae) from the Late Triassic of southern Brazil: anatomical and biostratigraphic implications | journal = Anais da Academia Brasileira de Ciências | volume = 83 | issue = 1 | doi = 10.1590/S0001-37652011000100021 | issn = 0001-3765 | pages=329–354| pmid = 21437390 | doi-access = free }}</ref>
}}

== External links ==
{{Portal|Dinosaurs}}
* {{cite news
 | title = New dinosaur uncovered in Brazil
 | url = http://news.bbc.co.uk/1/hi/sci/tech/4064429.stm
 | first = Steve | last = Kingstone
 | publisher = BBC News
 | date = 2004-12-03
 }}
* {{cite news
 | url=https://www.nbcnews.com/id/wbna6639601
 | archive-url=https://web.archive.org/web/20041210145806/http://www.msnbc.msn.com/id/6639601/
 | url-status=live
 | archive-date=2004-12-10
 | title= Brazilians find dinosaur linked to Europe
 | first=Andrei  | last=Khalip
 | publisher = MSNBC
 | date = 2004-12-02
 }}
* {{cite news
 |url         = http://www.news24.com/News24/Technology/News/0,,2-13-1443_1630520,00.html
 |title       = New dinosaur uncovered
 |publisher   = News 24
 |date        = 2004-12-03
 |url-status     = dead
 |archive-url  = https://web.archive.org/web/20070930220637/http://www.news24.com/News24/Technology/News/0,,2-13-1443_1630520,00.html
 |archive-date = 2007-09-30
}}
*[http://www.royalsul.com.br/paleo/galeria.asp Dinosaurs of Rio grande do Sul.]
{{Sauropodomorpha|S.}}
{{Taxonbar|from=Q133130}}

[[Category:Unaysauridae]]
[[Category:Dinosaur genera]]
[[Category:Norian dinosaurs]]
[[Category:Taxa named by Alexander Kellner]]
[[Category:Fossil taxa described in 2004]]
[[Category:Dinosaurs of Brazil]]