View source for Indosaurus

{{Short description|Extinct genus of dinosaurs}}
{{Distinguish|Indosuchus|Inosaurus}}
{{speciesbox
| fossil_range = [[Late Cretaceous]], {{fossilrange|69|66|earliest=70.6}}
| image = Indosaurus.jpg
| image_caption = [[Skull]] [[bone]]
| display_parents = 2
| genus = Indosaurus
| species = matleyi
| authority = [[Friedrich von Huene|Huene]] & [[Charles Alfred Matley|Matley]], [[1933 in paleontology|1933]]
}}'''''Indosaurus''''' ({{lit|Indian lizard}}) is a [[genus]] of dubious carnivorous [[theropod]] [[dinosaur]] that lived in what is now [[India]], about 69 to 66 million years ago during the [[Maastrichtian]] division of the Late [[Cretaceous]].<ref>{{Cite news|url=https://www.hindustantimes.com/more-lifestyle/a-raja-a-jain-a-tagore-meet-desi-dinosaurs-that-once-roamed-india-s-plains/story-EEfvnpOJjsoJUlV0vmjjKP.html|title=A raja, a Jain, a Tagore: Meet desi dinosaurs that once roamed India's plains|last=Lopez|first=Rachel|date=4 April 2017|work=Hindustan Times|access-date=24 September 2019|archive-date=24 September 2019|archive-url=https://web.archive.org/web/20190924045350/https://www.hindustantimes.com/more-lifestyle/a-raja-a-jain-a-tagore-meet-desi-dinosaurs-that-once-roamed-india-s-plains/story-EEfvnpOJjsoJUlV0vmjjKP.html|url-status=dead}}</ref><ref>{{Cite news |last=Shroff |first=Vaishali |date=12 August 2018 |title=Did you know about Indian dinosaurs? Meet the Rajasaurus |work=The Indian Express |url=https://indianexpress.com/article/parenting/learning/indian-dinosaurs-fossils-rajasaurus-5300209/ |access-date=24 September 2019}}</ref>

== Discovery and naming ==


{{Location map|India
|width = 225px
|coordinates={{coord|23.2|N|80.0|E|display=inline}}
|caption= ''Indosaurus'' [[Type locality (biology)|type locality]] in Carnosaur beds, Bara Simla, Jabalpur, [[Madhya Pradesh]], India
|pushpin_relief=1
}}


The now-lost [[holotype]] was discovered between 1917 and 1919 in [[Jabalpur]], India (GSI K27/565), by [[Charles Alfred Matley]].The [[type species]], '''''Indosaurus matleyi''''', was named by [[Friedrich von Huene|Huene]] and Matley in 1933 making ''Indosaurus'' the first [[Majungasaurinae|majungasaurine]] to be discovered.<ref>F. von Huene and C. A. Matley, 1933, "The Cretaceous Saurischia and Ornithischia of the Central Provinces of India", ''Palaeontologica Indica (New Series), Memoirs of the Geological Survey of India'' '''21'''(1): 1-74</ref> The generic name refers to India and the [[specific name (zoology)|specific name]] honours Matley. This species now also [[inclusion (taxonomy)|includes]] ''[[Megalosaurus]] matleyi''. Some [[paleontologist]]s have speculated that ''[[Indosuchus]],'' ''[[Lametasaurus]]'' and ''Indosaurus'' should be considered as nomina dubia.<ref>https://www.researchgate.net/publication/225243196_Rahiolisaurus_gujaratensis_n_gen_n_sp_A_New_Abelisaurid_Theropod_from_the_Late_Cretaceous_of_India {{Bare URL inline|date=August 2024}}</ref>

== Description ==
The parietal of the [[Frontoparietal network|frontal-parietal region]] is broad whereas the lower surface of the frontal is wide, the [[transverse crest]] lies above and behind the [[Orbitofrontal cortex|orbit]]. The frontals are concave and decline in to the front of the [[cranium]]. The [[supratemporal fossa]] is short and broad as in ''[[Antrodemus]]''.<ref name="Chatterjee-1978">{{cite journal |last=Chatterjee |first=Sankar |date=1978 |title=Indosuchus and Indosaurus, Cretaceous carnosaurs from India |url=https://www.researchgate.net/publication/291807131 |journal=[[Journal of Paleontology]] |volume=52 |issue=3 |pages=570–580 |via=[[ResearchGate]]}}</ref> The incomplete skull is of unusual thickness, although it lacked a dome on frontal bones as seen in ''[[Majungasaurus]]''. It would have also lacked the paired frontal horns seen in ''[[Carnotaurus]]''. Both ''[[Indosuchus]]'' and ''Indosaurus'' had a conservative skull roof which was dorsoventrally thickened but did not process prominences above the skull roof, similar to the condition seen in ''[[Abelisaurus]]''.<ref>https://www.researchgate.net/publication/288914603_Cretaceous_theropods_from_India_A_review_of_specimens_described_by_Huene_and_Matley_1933</ref>

The species ''I. matleyi'' weighed roughly {{cvt|700|kg}}.{{Citation needed|date=April 2025}}

== Classification ==
Originally assigned by Huene to the [[Allosauridae]], ''Indosaurus'' is today considered a member of the [[Abelisauridae]] family.<ref>{{Cite journal |last1=Tortosa |first1=Thierry |last2=Buffetaut |first2=Eric |last3=Vialle |first3=Nicolas |last4=Dutour |first4=Yves |last5=Turini |first5=Eric |last6=Cheylan |first6=Gilles |date=2014-01-01 |title=A new abelisaurid dinosaur from the Late Cretaceous of southern France: Palaeobiogeographical implications |url=https://www.sciencedirect.com/science/article/pii/S075339691300089X |journal=Annales de Paléontologie |language=en |volume=100 |issue=1 |pages=63–86 |doi=10.1016/j.annpal.2013.10.003 |bibcode=2014AnPal.100...63T |issn=0753-3969|url-access=subscription }}</ref> It shows similarities to the other Abelisaurids from India, such as ''[[Rajasaurus]]'' and ''[[Rahiolisaurus]]'', and is hence usually placed within Abelisauridae, though the fragmentary nature for this taxon makes it difficult to recognize its exact taxonomic validity.<ref name=":0">https://www.researchgate.net/publication/373144530_Review_of_the_Cretaceous_dinosaurs_from_India_and_their_paleobiogeographic_significance {{Bare URL inline|date=August 2024}}</ref>

In 2014 Thierry Tortosa erected the subfamily Majungasaurinae. This was to separate ''[[Arcovenator]]'', ''[[Majungasaurus]]'', ''Indosaurus'', ''[[Rahiolisaurus]]'', and ''[[Rajasaurus]]'' from South American abelisaurids based on physical characteristics such as elongated [[antorbital fenestra]]e in front of the eye sockets, and a sagittal crest that widens into a triangular surface towards the front of the head.

It was suggested that the abelisaurids migrated between Africa, Europe, India and Madagascar, which would isolate the South American abelisaurids. It is possible that migration occurred between Europe and India across Africa given its proximity to both, and the volcanic Dras-Kohistan island arc may have allowed [[island hopping]] and an indirect path to Asia, though these are still questionable explanations.<ref name="tortosa20142">{{cite journal |last1=Tortosa |first1=T. |last2=Buffetaut |first2=E. |last3=Vialle |first3=N. |last4=Dutour |first4=Y. |last5=Turini |first5=E. |last6=Cheylan |first6=G. |year=2014 |title=A new abelisaurid dinosaur from the Late Cretaceous of southern France: Palaeobiogeographical implications |journal=Annales de Paléontologie |volume=100 |issue=1 |pages=63–86 |bibcode=2014AnPal.100...63T |doi=10.1016/j.annpal.2013.10.003}}</ref><ref>{{cite journal |last1=Kapur |first1=V. V. |last2=Khosla |first2=A. |year=2016 |title=Late Cretaceous terrestrial biota from India with special reference to vertebrates and their implications for biogeographic connections |url=https://www.researchgate.net/publication/308209674 |journal=Cretaceous Period: Biotic Diversity and Biogeography |volume=71 |pages=161–172}}</ref>

The following cladogram was recovered by Tortosa (2014):<ref name="tortosa20142"/>
{{clade| style=font-size:100%; line-height:100%
|label1=[[Ceratosauria]]
|1={{clade
 |1=''[[Ceratosaurus]]'' 
 |2=[[Noasauridae]] 
 |3={{clade
 |label1=[[Abelisauridae]]
 |1={{clade
  |1={{clade
   |label1=[[Carnotaurinae]]
   |1={{clade
    |1=''[[Carnotaurus]]'' [[File:Cartography of South America.svg|15px]]
    |2=''[[Abelisaurus]]'' [[File:Cartography of South America.svg|15px]]
      }}
     }}
  |2={{clade
  |label1=[[Majungasaurinae]]
  |1={{clade
   |1=''[[Rajasaurus]]'' [[File:Cartography of Asia.svg|15px]]
   |2=''[[Majungasaurus]]'' [[File:Cartography of Africa.svg|15px]]
   |3=''Indosaurus'' [[File:Cartography of Asia.svg|15px]]
   |4=''[[Rahiolisaurus]]'' [[File:Cartography of Asia.svg|15px]]
   |5=''[[Arcovenator]]'' [[File:Cartography of Europe.svg|15px]]
     }} }} }} }} }} }}

==Paleoecology==
''Indosaurus'' lived in the [[Lameta Formation]] during the [[Maastrichtian]] age of the [[Cretaceous]] period. It is known to have lived alongside [[sauropods]] like ''[[Isisaurus]]'', ''[[Jainosaurus]]'' and the dubious ''[[Titanosaurus]]'', which it may have preyed upon. Other [[ceratosaurs]] such as the abelisaurid ''Rajasaurus'', ''Rahiolisaurus'' and ''Indosuchus'' are known from the formation, along with the [[Noasauridae|noasaurid]] ''[[Laevisuchus]]''. The [[ichnogenus]] ''[[Deltapodus]]'' is also known from the formation, which may belong to the youngest know [[stegosaurid]]. The [[Madtsoiidae|madtsoiid]] snake ''[[Sanajeh]]'' was also contemporaneous to ''Indosaurus''.

The rocks of the Lameta formation appear to have been deposited in [[Fluvial sediment processes|fluvial]] or [[Lacustrine deposits|lacustrine]] conditions. The environment at the time of deposition has alternatively been considered [[semi-arid]], or tropical humid.<ref>{{Cite journal |last1=Srivastava |first1=Ashok K. |last2=Mankar |first2=Rupesh S. |date=January 2015 |title=Lithofacies architecture and depositional environment of Late Cretaceous Lameta Formation, central India |url=http://link.springer.com/10.1007/s12517-013-1192-y |journal=Arabian Journal of Geosciences |language=en |volume=8 |issue=1 |pages=207–226 |doi=10.1007/s12517-013-1192-y |bibcode=2015ArJG....8..207S |issn=1866-7511 |s2cid=67851941|url-access=subscription }}</ref><ref>{{Cite journal |last1=Kumari |first1=Anjali |last2=Singh |first2=Seema |last3=Khosla |first3=Ashu |date=January 2021 |title=Palaeosols and palaeoclimate reconstruction of the Maastrichtian Lameta Formation, Central India |url=https://linkinghub.elsevier.com/retrieve/pii/S0195667120303189 |journal=Cretaceous Research |language=en |volume=117 |pages=104632 |bibcode=2021CrRes.11704632K |doi=10.1016/j.cretres.2020.104632 |s2cid=224946979|url-access=subscription }}</ref>

The dinosaurs in India probably all went extinct due to volcanic activity around 350,000 years before the [[Cretaceous–Paleogene boundary]]. Dinosaurs probably avoided areas with volcanic [[fissure vent]]s and [[lava flow]]s.<ref>{{cite journal |last1=Mohabey |first1=D. M. |last2=Samant |first2=B. |year=2013 |title=Deccan continental flood basalt eruption terminated Indian dinosaurs before the Cretaceous–Paleogene boundary |url=https://www.researchgate.net/publication/263733418 |journal=Geological Society of India Special Publication |pages=260–267 |number=1}}</ref>

==See also==
{{Portal|Dinosaurs}}
* [[Timeline of ceratosaur research]]

==References==
{{Reflist}}

{{Theropoda|B.}}
{{Taxonbar|from=Q135312}}

[[Category:Abelisauridae]]
[[Category:Dinosaur genera]]
[[Category:Maastrichtian dinosaurs]]
[[Category:Fossil taxa described in 1933]]
[[Category:Taxa named by Charles Alfred Matley]]
[[Category:Taxa named by Friedrich von Huene]]
[[Category:Dinosaurs of India]]


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