Secernosaurus: Difference between revisions

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{{Short description|Extinct genus of dinosaurs}}

{{Taxobox

{{Automatic taxobox

| color = pink

| fossil_range = [[Late Cretaceous]], {{fossil range|68|66}}

| name = ''Secernosaurus''

| statustaxon = fossilSecernosaurus

| image = Secernosaurus koerneri.png

| fossil_range = [[Late Cretaceous]]

| regnumimage_caption = [[AnimalLife restoration]]ia

| authority = Brett-Surman, 1979

| phylum = [[Chordata]]

| type_species = {{extinct}}'''''Secernosaurus koerneri'''''

| classis = [[Sauropsida]]

| type_species_authority = Brett-Surman, 1979

| superordo = [[Dinosauria]]

| ordo = [[Ornithischia]]

| subordo = [[Ornithopoda]]

| infraordo = [[Iguanodont]]ia

| superfamilia = [[Hadrosauroidea]]

| familia = [[Hadrosauridae]]?

| genus = '''''Secernosaurus'''''

| species = '''''S. koerneri'''''

| binomial = ''Secernosaurus koerneri''

| binomial_authority = Brett-Surman, [[1979]]

}}

'''''Secernosaurus''''' (meaning "severed lizard") is a [[genus]] of [[herbivore|herbivorous]] [[Hadrosauridae|hadrosaurid]] [[dinosaur]] that lived during the Late [[Cretaceous]] of what is now [[Argentina]]. This genus and its close relatives lived in South America, unlike most hadrosaurids, which lived in the [[Laurasia]]n continents of Eurasia and North America. It has been suggested that the ancestors of ''Secernosaurus'' crossed into South America when a land bridge temporarily formed between North and South America during the Late Cretaceous and allowed [[biotic interchange]] between the two continents.

==History of research==

'''''Secernosaurus''''' (meaning "severed lizard") is the name given to a genus of herbivorous [[dinosaur]]s. ''Secernosaurus'' was a [[hadrosaur]], a "duck-billed" dinosaur which lived during the Late [[Cretaceous]]. Its fossils have been found in [[Argentina]].

The holotype of ''Secernosaurus koeneri'' was collected in 1923 as part of an expedition by the [[Field Museum]] led by J. B. Abbott. However, the specimen was not studied until the 1970s.<ref name="prietomarquez2010"/> In 1979, Brett-Surman named ''Secernosaurus''. Though hadrosaurid specimens from South America had been described before, ''Secernosaurus koeneri'' was the first species of South American hadrosaurid to be formally named. The genus name ''Secernosaurus'' means "separated reptile"<ref name="holtz2007"/> and comes from the Latin verb ''[[Wiktionary:secerno|sēcernō]]'', meaning to sever or divide, in reference to its geographic ___location separated from Laurasian hadrosaurs. The species name ''S. koerneri'' honors Harold E. Koerner.<ref name="brettsurman1979"/> The holotype of ''Secernosaurus koerneri'' is [[Field Museum of Natural History|FMNH]] P13423,<ref name="prietomarquez2010"/> a partial skeleton from the [[Lago Colhué Huapi Formation]] of Chubut province, Argentina.<ref name="ibiricu2020"/>

In 2010, Albert Prieto-Marquez and Guillermo Salinas argued that ''[[Kritosaurus]] australis'' was synonymous with ''Secernosaurus koeneri''.<ref name="prietomarquez2010"/> However, in 2015, Rodolfo Coria noted differences between the two, and suggested their taxonomy needed reevaluation.<ref name="coria2015"/> In 2022, the two species were recognized as separate and the genus ''[[Huallasaurus]]'' was established for ''Kritosaurus australis''.<ref name="rozadilla2022"/>

The type species is ''Secernosaurus koerneri'', described in [[1979]].

==ReferencesDescription==

''Secernosaurus'' may have been small for a hadrosaurid. The type specimen pertains to an individual approximately {{convert|4|-|5|m|ft}} long, which was initially suggested to be a subadult, but has been suggested that it may have been more mature than previously thought.<ref name="coria2015"/> The neuroanatomy of ''S. koerneri'' was very similar to that of hadrosaurids from the [[Northern Hemisphere]].<ref>{{Cite journal |last1=Becerra |first1=Marcos |last2=Paulina-Carabajal |first2=Ariana |last3=Cruzado-Caballero |first3=Penélope |last4=Taborda |first4=Jeremías |date=2018 |title=First endocranial description of a South American hadrosaurid: The neuroanatomy of Secernosaurus koerneri from the Late Cretaceous of Argentina |url=http://www.app.pan.pl/article/item/app005262018.html |journal=[[Acta Palaeontologica Polonica]] |volume=63 |doi=10.4202/app.00526.2018 |access-date=14 April 2025|hdl=11336/88722 |hdl-access=free }}</ref>

* http://www.users.qwest.net/~jstweet1/hadrosauridae.htm

==Classification==

[[Category:Cretaceous dinosaurs]]

[[File:Hadrosaur_museum.jpg|thumb|''[[Huallasaurus]]'', once considered a [[junior synonym]] of ''Secernosaurus'', is still considered a close relative]]

[[Category:Hadrosaurs]]

[[File:Gryposaurus notabilis.png|thumb|''Secernosaurus'' was a close relative of North American kritosaurins such as ''Gryposaurus'']]

[[Category:South American dinosaurs]]

[[Phylogenetic analyses]] have found ''Secernosaurus'' to be a member of the hadrosaurid [[tribe (taxonomy)|tribe]] [[Kritosaurini]] within the subfamily [[Saurolophinae]]. North American animals such as ''[[Kritosaurus]]'' and ''[[Gryposaurus]]'' are also part of this [[clade]].<ref name="prietomarquez2010"/> Rozadilla ''et al''. (2022) recovered all South American saurolophines to group together within a single clade consisting of ''Secernosaurus'', ''[[Huallasaurus]]'', ''[[Kelumapusaura]]'', and ''[[Bonapartesaurus]]''.<ref name="rozadilla2022"/> In the 2023 [[Species description|description]] of the South American [[hadrosauroid]] ''[[Gonkoken]]'', Alarcón-Muñoz ''et al''. named the [[Austrokritosauria]], a clade closely related to kritosaurins, consisting of all the South American saurolophines. The results of their phylogenetic analyses of Saurolophinae are displayed in the [[cladogram]] below:<ref name="Austrokritosauria">{{Cite journal |last1=Alarcón-Muñoz |first1=Jhonatan |last2=Vargas |first2=Alexander O. |last3=Püschel |first3=Hans P. |last4=Soto-Acuña |first4=Sergio |last5=Manríquez |first5=Leslie |last6=Leppe |first6=Marcelo |last7=Kaluza |first7=Jonatan |last8=Milla |first8=Verónica |last9=Gutstein |first9=Carolina S. |last10=Palma-Liberona |first10=José |last11=Stinnesbeck |first11=Wolfgang |last12=Frey |first12=Eberhard |last13=Pino |first13=Juan Pablo |last14=Bajor |first14=Dániel |last15=Núñez |first15=Elaine |first16=Héctor |last16=Ortiz |first17=David |last17=Rubilar-Rogers |first18=Penélope |last18=Cruzado-Caballero |date=2023-06-16 |title=Relict duck-billed dinosaurs survived into the last age of the dinosaurs in subantarctic Chile |journal=Science Advances |language=en |volume=9 |issue=24 |article-number=eadg2456 |doi=10.1126/sciadv.adg2456 |pmid=37327335 |issn=2375-2548 |pmc=10275600 |bibcode=2023SciA....9G2456A }}</ref>

{{clade| style=font-size:90%;line-height:85%

{{Dinosaur-stub}}

|label1=[[Saurolophinae]]

|1={{clade

|1={{clade

|1={{clade

|1=''[[Wulagasaurus]]''[[File:Wulagasaurus dongi.png|60px]]

|2=''[[Acristavus]]''[[File:Acristavus gagslarsoni.png|60px]] }}

|2={{clade

|1=''[[Maiasaura]]'' [[File:Maiasaura peeblesorum.png|60px]]

|2={{clade

|1=''[[Probrachylophosaurus]]'' [[File:Probrachylophosaurus bergei.png|60px]]

|2=''[[Brachylophosaurus]]'' [[File:Brachylophosaurus canadensis.png|60px]] }} }} }}

|2={{clade

|1={{clade

|label1=[[Austrokritosauria]]

|1={{clade

|1='''''Secernosaurus''''' [[File:Secernosaurus koerneri.png|60px]]

|2={{clade

|1=''[[Bonapartesaurus]]'' [[File:Bonapartesaurus rionegrensis.png|60px]]

|2={{clade

|1=''[[Kelumapusaura]]'' [[File:Kelumapusaura machi.png|60px]]

|2=''[[Huallasaurus]]'' [[File:Huallasaurus australis.png|60px]] }} }} }}

|label2=[[Kritosaurini]]

|2={{clade

|1=''[[Kritosaurus]]'' [[File:Kritosaurus navajovius.png|60px]]

|2={{clade

|1={{clade

|1=''[[Rhinorex]]'' [[File:Rhinorex condrupus.png|60px]]

|2=''[[Gryposaurus latidens]]'' }}

|3={{clade

|1=''Gryposaurus notabilis'' [[File:Gryposaurus notabilis.png|60px]]

|2=''Gryposaurus monumentensis'' }} }} }} }}

|2={{clade

|1=''[[Kamuysaurus]]'' [[File:Kamuysaurus japonicus.png|60px]]

|2={{clade

|1={{clade

|1=''[[Prosaurolophus]]'' [[File:Prosaurolophus maximus.png|60px]]

|2={{clade

|1=''[[Saurolophus osborni]]'' [[File:Saurolophus osborni.png|60px]]

|2=''Saurolophus angustirostris'' [[File:Saurolophus angustirostris.png|60px]]}} }}

|2={{clade

|1={{clade

|1=''[[Laiyangosaurus]]'' [[File:Laiyangosaurus youngi.png|60px]]

|2=''[[Kerberosaurus]]'' [[File:Kerberosaurus manakini.png|60px]] }}

|2={{clade

|1=''[[Shantungosaurus]]'' [[File:Shantungosaurus giganteus.png|60px]]

|2={{clade

|1=''[[Edmontosaurus regalis]]'' <div style="{{MirrorH}}">[[File:Edmontosaurus BW.jpg|60px]]</div>

|2=''[[Edmontosaurus annectens]]'' [[File:Anatotitan BW.jpg|60px]]

}} }} }} }} }} }} }} }}

==Palaeoecology==

[[de:Secernosaurus]]

===Palaeoenvironment===

[[it:Secernosaurus koerneri]]

{{multiple image

[[pt:Secernossauro]]

|align = right

|direction = vertical

|total_width = 300

|image1 = Yardangs_in_dunes,_White_Sands_National_Park,_New_Mexico,_United_States.jpg

|alt1 = Gypsum desert dunes

|image2 = Toklat_River_-_East_Fork_01.jpg

|alt2 = Braided river ecosystem

|footer = The environment ''Secernosaurus'' lived in fluctuated between arid, gypsum-rich conditions and seasonally wet conditions over a short span of geologic time

}}

The geologic layers of the [[Lago Colhué Huapi Formation]], where ''Scernosaurus'' hails from, have proved difficult to interpret historically, their assignment shifting around between several different [[geologic formation]]s before finally being settled as its own unit of the [[Chubut Group]], dating to the [[Maastrichtian]]. Additionally, ''Secernosaurus'' specifically had a very uncertain geologic provenance. As a result, the ecosystem ''Secernosaurus'' would have lived in was not well understood historically. A 2016 paper by Casal A. Gabriel and colleagues studied the climatic conditions of the region more in depth, finding evidence of climate change across geologic time. Fluvial systems and evidence of a floodplain environment were recognized, but the geologically lower parts of the formation also showed evidence of semi-arid conditions, large [[gypsum]] deposits, and desiccation cracks, indicating intense aridization of the region compared to the very humid climate of the [[Bajo Barreal Formation]]'s ecosystem that preceded Lago Colhué Huapi Formation. However, [[palynological]] data indicate that during the upper deposits of the formation at the very end of the [[Cretaceous]] and into the [[Danian]] age of the [[Paleocene]], the climate became milder once again and returned to a balanced wet and dry season. It is from this uppermost part of the formation that ''Secernosaurus'' is from. More recent discoveries of hadrosaur remains from other localities, which could belong to ''Secernosaurus'' might extend the range within the formation hadrosaurs are found in. Currently, however, they have not been researched in depth.<ref name="casal2016">{{cite journal | url=https://www.sbpbrasil.org/assets/uploads/files/rbp19-1/05_Casal%20et%20al_pg53a70_wb.pdf | title=Ordenamiento y caracterización faunística del Cretácico Superior del Grupo Chubut, Cuenca del Golfo San Jorge, Argentina. | journal=Revista Brasileira de Paleontologia | year=2016 | volume=19 | issue=1 | pages=53–70 | doi=10.4072/rbp.2016.1.05| last1=Casal | first1=Gabriel A. | last2=Martínez | first2=Rubén D. | last3=Luna | first3=Marcelo | last4=Ibiricu | first4=Lucio M. | bibcode=2016RvBrP..19...53C }}</ref>

''Secernosaurus'' is not the only dinosaur known from Lago Colhué Huapi. Remains of the [[sauropod]]s ''[[Elaltitan lilloi]]'', ''[[Argyrosaurus superbus]]'' and ''[[Aeolosaurus colhuehuapensis]]'', as well as unidentified sauropod remains found in 2010, have been discovered in the formation. Very fragmentary remains of [[dromaeosaurid]] and [[megaraptoran]] theropods such as ''[[Joaquinraptor]]''<ref>{{Cite journal |last1=Ibiricu |first1=Lucio M. |last2=Lamanna |first2=Matthew C. |last3=Alvarez |first3=Bruno N. |last4=Cerda |first4=Ignacio A. |last5=Caglianone |first5=Julieta L. |last6=Cardozo |first6=Noelia V. |last7=Luna |first7=Marcelo |last8=Martínez |first8=Rubén D. |year=2025 |title=Latest Cretaceous megaraptorid theropod dinosaur sheds light on megaraptoran evolution and palaeobiology |journal=[[Nature Communications]] |volume=16 |article-number=8298 |doi=10.1038/s41467-025-63793-5 |doi-access=free |pmc=12457595 }}</ref> have also been discovered, as is expected from other formations from a similar time and place. The enigmatic [[ornithischian]] dinosaur ''[[Notoceratops]]'', based on a lost fragmentary specimen originally considered to belong to a [[ceratopsian]] but now debated between that identity and that of a hadrosaur. Finally, scant fossils of [[chelonians]], [[crocodyliformes]], and [[dipnoi]]d fish have also been found.<ref name=casal2016/>

===Palaeobiogeography===

[[File:LateCretaceousMap.jpg|thumb|Map of the continents in the Late Cretaceous; the southern "Gondwanan" continents were diverging, with South America becoming isolated from other continents]]

''Secernosaurus'' lived in what is now Patagonia during the [[Maastrichtian]] age of the Cretaceous period.<ref name="ibiricu2020"/> It was one of the few hadrosaurs to live in South America. Their presence in South America is likely to represent a dispersal event from North America during the [[Campanian]], when the proto-[[Antilles]] may have formed an island chain that allowed land vertebrates to cross between the two continents.<ref name="prietomarquez2010"/> The arrival of hadrosaurids in South America may have caused the decline of the native ornithopods, the [[elasmarians]].<ref name="ibiricu2020"/>

== See also ==

* [[Timeline of hadrosaur research]]

* ''[[Alamosaurus]]''– a [[titanosaur]] whose ancestors may have crossed into North America at the same time the ancestors of ''Secernosaurus'' crossed into South America <ref name="demic2010"/>

* ''[[Huallasaurus]]''

* ''[[Kritosaurus]]''

== References ==

{{Reflist|refs=

<ref name="brettsurman1979">{{Cite journal| doi = 10.1038/277560a0| issn = 0028-0836| volume = 277| pages = 560–562| last = Brett-Surman| first = M. K.| title = Phylogeny and palaeobiogeography of hadrosaurian dinosaurs| journal = Nature| date = 1979-12-15| issue = 5697| bibcode = 1979Natur.277..560B| s2cid = 4332144}}</ref>

<ref name="coria2015">{{Cite book| publisher = Indiana University Press| isbn = 978-0-253-01390-3| pages = 332–339| editor-first1 = David A. | editor-last1 = Eberth | editor-first2 = David C. | editor-last2 = Evans | last1 = Coria| first1 = Rodolfo A| title = Hadrosaurs| chapter = South American hadrosaurs: considerations on their diversity| ___location = Bloomington and Indianapolis| series = Life of the past| date = 2015}}</ref>

<ref name="demic2010">{{Cite journal| doi = 10.1016/j.palaeo.2010.08.032| issn = 0031-0182| volume = 297| issue = 2| pages = 486–490| last1 = D'Emic| first1 = Michael D.| last2 = Wilson| first2 = Jeffrey A.| last3 = Thompson| first3 = Richard| title = The end of the sauropod dinosaur hiatus in North America| journal = Palaeogeography, Palaeoclimatology, Palaeoecology| date = 2010 | bibcode = 2010PPP...297..486D| url = https://linkinghub.elsevier.com/retrieve/pii/S0031018210005262| url-access = subscription}}</ref>

<ref name="holtz2007">{{cite book | first1 = T. R. | last1 = Holtz | title = Dinosaurs: the most complete, up-to-date encyclopedia for dinosaur lovers of all ages | year = 2007 | publisher = Random House | ___location = New York | isbn = 978-0-375-82419-7 }}</ref>

<ref name="ibiricu2020">{{Cite journal| doi = 10.1016/j.jsames.2019.102460| issn = 0895-9811| volume = 98| article-number = 102460| last1 = Ibiricu| first1 = Lucio M.| last2 = Casal| first2 = Gabriel A.| last3 = Martínez| first3 = Rubén D.| last4 = Alvarez| first4 = Bruno N.| last5 = Poropat| first5 = Stephen F.| title = New materials and an overview of Cretaceous vertebrates from the Chubut Group of the Golfo San Jorge Basin, central Patagonia, Argentina| journal = Journal of South American Earth Sciences| date = 2020 | bibcode = 2020JSAES..9802460I| s2cid = 212808289| url = https://linkinghub.elsevier.com/retrieve/pii/S0895981119303840| url-access = subscription}}</ref>

<ref name="prietomarquez2010">{{cite journal |last=Prieto–Marquez |first=Alberto |author2=Salinas, Guillermo C. |year=2010 |title=A re–evaluation of Secernosaurus koerneri and Kritosaurus australis (Dinosauria, Hadrosauridae) from the Late Cretaceous of Argentina |journal=Journal of Vertebrate Paleontology |volume=30 |issue=3 |pages=813–837 |doi=10.1080/02724631003763508|bibcode=2010JVPal..30..813P |s2cid=85814033 }}</ref>

<ref name="rozadilla2022">{{Cite journal|last1=Rozadilla|first1=Sebastián|last2=Brissón-Egli|first2=Federico|last3=Agnolín|first3=Federico Lisandro|last4=Aranciaga-Rolando|first4=Alexis Mauro|last5=Novas|first5=Fernando Emilio|date=2022-02-24|title=A new hadrosaurid (Dinosauria: Ornithischia) from the Late Cretaceous of northern Patagonia and the radiation of South American hadrosaurids|journal=Journal of Systematic Palaeontology|volume=19|issue=17|pages=1207–1235|doi=10.1080/14772019.2021.2020917|s2cid=247122005|issn=1477-2019}}</ref>

}}

{{Ornithopoda|H.}}

{{Taxonbar|from=Q134692}}

{{Portal bar|Dinosaurs|Paleontology}}

[[Category:Saurolophinae]]

[[Category:Dinosaur genera]]

[[Category:Maastrichtian dinosaurs]]

[[Category:Los Alamitos Formation]]

[[Category:Fossil taxa described in 1979]]

[[Category:Dinosaurs of Argentina]]