Maryslanker at 02:44, 12 April 2026

2026-04-12T02:44:49Z

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{{Short description|Extinct genus of dinosaurs}}
{{Distinguish|Isaurus}}
{{Speciesbox
| name = ''Isisaurus''
| fossil_range = [[Late Cretaceous]] ([[Maastrichtian]]), {{fossilrange|70|66|latest=66}}{{Period fossil range|Cretaceous|70|66}}
| image = Isisaurus colberti life restoration.png
| image_caption = [[Life restoration]]
| genus = Isisaurus
| species = colberti
| parent_authority = Wilson & Upchurch, 2003
| authority = ([[Sohan Lal Jain|Jain]] & Bandyopadhyay, 1997)
| synonyms = * ''[[Titanosaurus]] colberti'' <br /><small>Jain & Bandyopadhyay, 1997 </small>
}}

'''''Isisaurus''''' (named after the [[Indian Statistical Institute]]) is a genus of [[titanosaur]]ian [[dinosaur]] from the [[Late Cretaceous]] [[Lameta Formation]] of [[India]] and [[Pab Formation]] of [[Pakistan]]. The genus contains a single species, '''''Isisaurus colberti'''''.

==Discovery and Naming==
{{Location map+ |India
|places =
{{Location map~ |India
|lat_deg = 21.2
|lon_deg = 80.4 }}
{{Location map~ |India
| coordinates = {{coord|21.4|78.0}}
}}
|caption = ''Isisaurus'' (''I. colberti'') localities from [[Lameta Formation]], India.
}}
{{Location map+ |Pakistan
|places =
{{Location map~ |Pakistan
|lat_deg = 29.7
|lon_deg = 69.5 }}
{{Location map~ |Pakistan
| coordinates = {{coord|29.7|69.4}}
}}
|caption = ''Isisaurus'' (''I. colberti'') localities from [[Pab Formation]], Pakistan.
}}
The [[type specimen]] of ''Isisaurus colberti'', ISI R 335/1-65, was originally described and named as ''[[Titanosaurus]] colberti'' by [[Sohan Lal Jain]] and Saswati Bandyopadhyay in 1997. The [[specific name (zoology)|specific name]] honours [[Edwin Harris Colbert]].<ref name= "Jain">{{cite journal |last1= Jain |first1= Sohan L. |last2= Bandyopadhyay |first2= Saswati |year= 1997 |title= New Titanosaurid (Dinosauria: Sauropoda) from the Late Cretaceous of Central India |journal= [[Journal of Vertebrate Paleontology]] |location= Norman, Okla. |publisher= University of Oklahoma |volume= 17 |number= 1 |page= 114 |doi=10.1080/02724634.1997.10010958|bibcode= 1997JVPal..17..114J }}</ref><ref name= "PD">{{cite web |url= https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=64311 |title= Isisaurus colberti |publisher= Paleobiology Database |access-date= December 31, 2012}}</ref> In 2003, the fossils were designated as belonging to its own genus by Wilson and Upchurch.<ref>{{cite journal |url= http://www-personal.umich.edu/~wilsonja/JAW/Publications_files/Wilson%26Upchurch2003.pdf |last1= Wilson |first1= Jeffrey A. |author-link= Jeffrey A. Wilson |last2= Upchurch |first2= P. |title= A revision of Titanosaurus Lydekker (Dinosauria – Sauropoda), the first dinosaur genus with a 'Gondwanan' distribution |journal= [[Journal of Systematic Palaeontology]] |location= Cambridge, U.K. |publisher= Cambridge University Press |volume= 1 |issue= 3 |year= 2003 |pages= 125–160 |access-date= December 31, 2012 |doi=10.1017/s1477201903001044|bibcode= 2003JSPal...1..125W |s2cid= 53997295 }}</ref> The generic name, "''Isisaurus''," combines a reference to the Indian Statistical Institute (ISI) with the [[Greek language|Greek]] "saurus," meaning "lizard." It had a short, vertically directed neck and long forelimbs,{{citation needed|date=May 2017}} making it considerably different from other sauropods. The [[humerus]] is 148 centimetres long.<ref name= "Jain"/>

The site locality is Dongargaon Hill, which is in a [[Maastrichtian]] crevasse splay [[claystone]] in the [[Lameta Formation]] of India.<ref name="PD" /> Dongargaon Hill (20.212318N,79.090709E) is located near [[Warora]], in [[Chandrapur district|Chandrapur District]], [[Maharashtra]].

A braincase referrable to the species is known from the [[Pab Formation]] of Pakistan, which is equivalent in age to the Lameta Formation.''<ref name=":1">{{Cite journal |last1=Wilson |first1=Jeffrey A. |last2=Barrett |first2=Paul M. |last3=Carrano |first3=Matthew T. |date=September 2011 |title=An associated partial skeleton of Jainosaurus cf. septentrionalis (Dinosauria: Sauropoda) from the Late Cretaceous of Chhota Simla, Central India |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1475-4983.2011.01087.x |journal=Palaeontology |language=en |volume=54 |issue=5 |pages=981–998 |doi=10.1111/j.1475-4983.2011.01087.x|bibcode=2011Palgy..54..981W |s2cid=55975792 |hdl=2027.42/86940 |hdl-access=free }}</ref>''

''Isisaurus'' is known from better remains than many other titanosaurs that were known at the time of its description. Much of its [[postcranial]] skeleton is known. The skeletal material found by Jain and Bandyopadhyay between 1984 and 1986 was "in associated and mostly articulated condition." The holotype includes [[Cervical vertebrae|cervical]], [[Thoracic vertebrae|dorsal]], [[Sacrum|sacral]] and [[Vertebra|caudal]] vertebrae, ribs, pelvis, scapula, coracoid, left [[Limb (anatomy)|forelimb]] and other bones. No skull, [[hindlimb]], or foot bones are known.<ref name= "Jain" /> Since the original description of ''Isisaurus'', unrelated titanosaur fossils belonging to more complete individuals have been discovered elsewhere.<ref>{{Cite journal|last1=Lacovara|first1=Kenneth J.|last2=Lamanna|first2=Matthew C.|last3=Ibiricu|first3=Lucio M.|last4=Poole|first4=Jason C.|last5=Schroeter|first5=Elena R.|last6=Ullmann|first6=Paul V.|last7=Voegele|first7=Kristyn K.|last8=Boles|first8=Zachary M.|last9=Carter|first9=Aja M.|last10=Fowler|first10=Emma K.|last11=Egerton|first11=Victoria M.|date=2014-09-04|title=A Gigantic, Exceptionally Complete Titanosaurian Sauropod Dinosaur from Southern Patagonia, Argentina|journal=Scientific Reports|language=en|volume=4|issue=1|page=6196|doi=10.1038/srep06196|issn=2045-2322|pmc=5385829|pmid=25186586}}</ref><ref>{{Cite journal|last1=Carballido|first1=José L.|last2=Pol|first2=Diego|last3=Otero|first3=Alejandro|last4=Cerda|first4=Ignacio A.|last5=Salgado|first5=Leonardo|last6=Garrido|first6=Alberto C.|last7=Ramezani|first7=Jahandar|last8=Cúneo|first8=Néstor R.|last9=Krause|first9=Javier M.|date=2017-08-16|title=A new giant titanosaur sheds light on body mass evolution among sauropod dinosaurs|journal=Proceedings of the Royal Society B: Biological Sciences|volume=284|issue=1860|article-number=20171219|doi=10.1098/rspb.2017.1219|pmc=5563814|pmid=28794222}}</ref>

==Description==
[[File:Isisaurus Size Comparison.svg|thumb|Size compared to a human]]
''Isisaurus'' was a medium-sized sauropod, with some estimates of its body length up to {{convert|18|m|ft}} long and weighing {{convert|15|MT|ST}}.<ref>{{Cite book|last=Paul|first=Gregory S.|title=The Princeton Field Guide to Dinosaurs|year=2016|publisher=Princeton University Press|isbn=978-1-78684-190-2|oclc=985402380|page=232}}</ref> The angle between the [[occipital bone]] and occipital condyle in ''Isisaurus'' and the fellow Indian titanosaur ''[[Jainosaurus]]'' is different. In the specimen from Dongargaon it is equal to 120°. In that matter, the cranium of ''Isisaurus'' resembles the skulls of ''[[Diplodocus]]'' and ''[[Apatosaurus]]'' (genera belonging to the [[Diplodocidae]]), but the bone modifications are different.<ref name="Wilson&09" />

==Classification==
While ''Isisaurus'' has consistently been considered to be a titanosaurian sauropod, its exact placement within this clade and its relationships with other titanosaurs has been controversial and problematic. Most analyses have recovered it with close affinities to taxa such as ''[[Rapetosaurus]]'' or the [[Saltasauridae]]. Various alternative positions suggested in that past are displayed in the following [[cladogram]]s:

''Isisaurus'' was placed within [[Opisthocoelicaudiinae]] by Curry-Rogers in 2005.<ref>{{Cite book |last1=Curry Rogers |first1=Kristina |title=The Sauropods: evolution and paleobiology |last2=Wilson |first2=Jeffrey A. |date=2005 |publisher=University of California Press |isbn=978-0-520-24623-2 |location=Berkeley}}</ref>

{{clade
|label1=[[Opisthocoelicaudiinae]]
|1={{clade
|1=''Isisaurus''
|2={{clade
|1=''[[Alamosaurus]]''
|2={{clade
|1=''[[Argentinosaurus]]''
|2=''[[Antarctosaurus]]''
|3=''[[Opisthocoelicaudia]]'' }} }} }} }}

The cladogram below follows Zaher et al. (2011).<ref>{{Cite journal |last1=Zaher |first1=Hussam |last2=Pol |first2=Diego |last3=Carvalho |first3=Alberto B. |last4=Nascimento |first4=Paulo M. |last5=Riccomini |first5=Claudio |last6=Larson |first6=Peter |last7=Juarez-Valieri |first7=Rubén |last8=Pires-Domingues |first8=Ricardo |last9=da Silva |first9=Nelson Jorge |last10=de Almeida Campos |first10=Diógenes |date=2011-02-07 |editor-last=Sereno |editor-first=Paul |title=A Complete Skull of an Early Cretaceous Sauropod and the Evolution of Advanced Titanosaurians |journal=PLOS ONE |language=en |volume=6 |issue=2 |article-number=e16663 |doi=10.1371/journal.pone.0016663 |doi-access=free |pmid=21326881 |pmc=3034730 |bibcode=2011PLoSO...616663Z |issn=1932-6203}}</ref>

{{clade
|label1=[[Lithostrotia]]
|1={{Clade
|1=''[[Malawisaurus]]''
|2={{Clade
|label1=[[Nemegtosauridae]]
|1={{Clade
|1=''[[Nemegtosaurus]]''
|2={{Clade
|1=''[[Rapetosaurus]]''
|2=''[[Tapuiasaurus]]'' }} }}
|2={{Clade
|1=''Isisaurus''
|2={{Clade
|1=''[[Diamantinasaurus]]''
|label2=[[Saltasauridae]]
|2={{Clade
|label1=[[Opisthocoelicaudiinae]]
|1={{Clade
|1=''[[Alamosaurus]]''
|2=''[[Opisthocoelicaudia]]'' }}
|label2=[[Saltasaurinae]]
|2={{Clade
|1=''[[Neuquensaurus]]''
|2=''[[Saltasaurus]]'' }} }} }} }} }} }} }}

In 2017, ''Isisaurus'' was recovered as the [[sister taxon]] to ''[[Tapuiasaurus]]''.<ref>{{Cite journal |last1=Carballido |first1=José L. |last2=Pol |first2=Diego |last3=Otero |first3=Alejandro |last4=Cerda |first4=Ignacio A. |last5=Salgado |first5=Leonardo |last6=Garrido |first6=Alberto C. |last7=Ramezani |first7=Jahandar |last8=Cúneo |first8=Néstor R. |last9=Krause |first9=Javier M. |date=2017-08-16 |title=A new giant titanosaur sheds light on body mass evolution among sauropod dinosaurs |journal=Proceedings of the Royal Society B: Biological Sciences |language=en |volume=284 |issue=1860 |article-number=20171219 |doi=10.1098/rspb.2017.1219 |pmid=28794222 |issn=0962-8452|pmc=5563814 }}</ref>

{{clade
|1={{clade
|1=''[[Baurutitan]]''
|2={{clade
|1={{clade
|1=[[Saltasauridae]]
|2=''[[Alamosaurus]]'' }}
|2={{clade
|1=''[[Rapetosaurus]]''
|2={{clade
|1=''[[Tapuiasaurus]]''
|2=''Isisaurus'' }} }} }} }} }}

In 2021, ''Isisaurus'' was placed as the sister taxon to ''[[Arackar]]''. The cladogram from Rubilar-Rogers et al. (2021) is shown below:<ref name="Arackar">{{Cite journal|last1=Rubilar-Rogers |first1=D. |last2=Vargas |first2=A. O. |last3=González Riga |first3=B. |last4=Soto-Acuña |first4=S. |last5=Alarcón-Muñoz |first5=J. |last6=Iriarte-Díaz |first6=J. |last7=Arévalo |first7=C. |last8=Gutstein |first8=C. S. |title=''Arackar licanantay'' gen. et sp. nov. a new lithostrotian (Dinosauria, Sauropoda) from the Upper Cretaceous of the Atacama Region, northern Chile |year=2021 |journal=Cretaceous Research |volume=124 |article-number=104802 |doi=10.1016/j.cretres.2021.104802 |bibcode=2021CrRes.12404802R |s2cid=233780252 }}</ref>

{{clade
|label1=[[Lithostrotia]]
|1={{clade
|1=''[[Malawisaurus]]''
|2={{clade
|1=''[[Baurutitan]]''
|2={{clade
|1={{clade
|1=''[[Rapetosaurus]]''
|2={{clade
|1=''[[Arackar]]''
|2=''Isisaurus'' }} }}
|2={{clade
|1=''[[Tapuiasaurus]]''
|2={{clade
|1=''[[Alamosaurus]]''
|2={{clade
|1=''[[Opisthocoelicaudia]]''
|2=[[Saltasaurinae]] }} }} }} }} }} }} }}

==Palaeobiology==
Fungus in [[coprolites]] believed to have been voided by ''Isisaurus'' indicate that it ate leaves from several species of tree, since these fungi are known to be [[pathogens]] which infect tree leaves.<ref name=sharmaetal2005>Sharma, N., Kar, R.K., Agarwal, A. and Kar, R. (2005). "Fungi in dinosaurian (''Isisaurus'') coprolites from the Lameta Formation (Maastrichtian) and its reflection on food habit and environment." ''Micropaleontology'', '''51'''(1): 73-82.</ref>

==Paleoecology==
[[File:Morning hunting in India.jpg|thumb|right|[[Life restoration]] of ''Isisaurus'' (middle) with contemporary [[dinosaurs]]]]
''Isisaurus'' lived in the area of present day central [[India]] and western [[Pakistan]] during the [[Maastrichtian]] age of the [[Cretaceous]] period.<ref name="Wilson">{{cite journal |last1=Wilson |first1=J. A. |title=An Overview of Titanosaur Evolution and Phylogeny |journal=Actas de las III Jornadas Internacionales Sobre Paleontología de Dinosaurios y Su Entorno, Salas de los Infantes, Burgos |date=2006 |url=http://www-personal.umich.edu/~wilsonja/JAW/Publications_files/Wilson2006b.pdf |access-date=2 September 2018}}</ref><ref name="González Riga">{{Cite journal |last=González Riga |first=Bernardo J. |date=2005 |title=Nuevos restos fósiles de Mendozasaurus neguyelap (Sauropoda, Titanosauria) del Cretácico Tardío de Mendoza, Argentina |trans-title=New fossil remains of Mendozasaurus neguyelap (Sauropoda, Titanosauria) of the Late Cretaceous of Mendoza, Argentina |url=http://www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S0002-70142005000300002 |journal=Ameghiniana |language=es |volume=42 |issue=3 |pages=535–548 |issn=0002-7014}} [https://naturalhistory.si.edu/sites/default/files/media/translated_publications/Gonzalez-Riga%252005.pdf English translation] by Michael D'Emic</ref> Its remains are the most complete among the Cretaceous dinosaurs known from that region.<ref name="Rajasaurus">{{cite journal |author=Jeffrey A. Wilson, Paul C. Sereno, Suresh Srivastava, Devendra K. Bhatt |title=A New Abelisaurid (Dinosauria, Theropoda) Grom The Lameta |journal=Contributions from the Museum of Paleontology |date=2003-08-15 |volume=31 |issue=1 |pages=1–42 |url=http://www-personal.umich.edu/~wilsonja/JAW/Publications_files/Wilson%26al2003.pdf |access-date=2 September 2018 |publisher=The University of Michigan}}</ref> Khosla et al. (2003) listed the following Indian sauropods:<ref name="Khosla&03">{{cite journal |author=Khosla, A., V. V. Kapur, P. C. Sereno, J. A. Wilson, G. P. Wilson, D. Dutheil, A. Sahni, M. P. Singh, S. Kumar |title=First dinosaur remains from the Cenomanian-Turonian Nimar Sandstone (Bagh Beds), district Dhar, Madhya Pradesh, India |journal=Journal of the Palaeontogical Society of India |date=2003 |volume=48 |pages=115–127 |doi=10.1177/0971102320030108 |url=http://www-personal.umich.edu/~wilsonja/JAW/Publications_files/Khosla%26al2004.pdf |access-date=2 September 2018}}</ref>
* ''[[Titanosaurus|Titanosaurus indicus]]''
* ''T. blanfordi''
* ''T. rahiolensis''
* ''[[Jainosaurus|Jainosaurus septentrionalis]]''.

Wilson et al. (2009) listed only two Indian titanosaurs, ''Isisaurus'' and its distant relative, ''Jainosaurus''. ''Isisaurus'' and ''Jainosaurus'' lived sympatrically in the area of middle and western India. ''Isisaurus'' fossils have also been reported from western [[Pakistan]].<ref name="Wilson&09">{{cite journal |author=Jeffrey A. Wilson, Michael D. D'emic, Kristina A. Curry Rogers, Dhananjay M. Mohabey & Subashis Sen |title=A reassessment of the sauropod dinosaur Jainosaurus (="Antarctosaurus") septentrionalis from the Upper Cretaceous of India |journal=Contributions from the Museum of Paleontology, University of Michigan |date=2009 |volume=32 |issue=2 |pages=17–40 |url=https://deepblue.lib.umich.edu/bitstream/handle/2027.42/63584/Contributions_32_no2_FINAL_07-14-09.pdf;jsessionid=AE4F8F10E0A9EEB8B3BAE81FFE7E4A26?sequence=1 |access-date=2 September 2018}}</ref>

Other dinosaurs, including the [[Abelisauridae|abelisaurs]] ''[[Indosuchus]]'', ''[[Rahiolisaurus]]'', and ''[[Rajasaurus]]'', also existed in the [[Lameta Formation]].

==References==
{{Commons category|position=left|Isisaurus}}
{{Reflist}}

{{Sauropodomorpha|T.}}
{{Portal bar|Dinosaurs|India}}
{{Taxonbar|from=Q311505}}

[[Category:Lithostrotia]]
[[Category:Dinosaur genera]]
[[Category:Maastrichtian dinosaurs]]
[[Category:Fossil taxa described in 2003]]
[[Category:Taxa named by Sohan Lal Jain]]
[[Category:Dinosaurs of India]]

Isisaurus - Revision history

Maryslanker at 02:44, 12 April 2026