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{{short description|Giant sauropod dinosaur genus from India}}
{{Use dmy dates|date=February 2024}}
{{Speciesbox
| fossil_range = [[Late Cretaceous]], {{fossil range|70}}
| image = Bruhathkayosaurus matleyi updated.png
| image_caption = Speculative [[life restoration]] of ''Bruhathkayosaurus''
| display_parents = 2
| parent_authority = Yadagiri & Ayyasami, 1987
| taxon = Bruhathkayosaurus matleyi
| authority = Yadagiri & Ayyasami, 1987
}}

'''''Bruhathkayosaurus''''' ({{IPAc-en|b|r|uː|ˌ|h|æ|θ|k|eɪ|oʊ-|ˈ|s|ɔːr|ə|s}}; meaning "huge-bodied lizard") is a genus of [[sauropod]] [[dinosaur]] found in the [[Kallamedu Formation]] of India. The fragmentary remains were originally described as a [[theropod]], but it was later determined to be a [[titanosaur]] sauropod. Length estimates by researchers exceed those of the titanosaur ''[[Argentinosaurus]]'',<ref name=Paul1994/> as longer than {{convert|35|m}} and weighing over 80 tonnes. A 2023 estimate placed ''Bruhathkayosaurus'' as potentially weighing {{convert|110|-|170|tonnes}}, with paleontologist [[Michael Benton]] estimating a length of {{convert|45|m}}.<ref name=DinosaurBehaviour>{{Cite book|last1=Benton|first1=Michael|date=31 October 2023 |title=Dinosaur Behavior: An Illustrated Guide|publisher=Princeton University Press|language=en |isbn=978-0-691-24429-7|pages=94–95}}</ref> If the upper estimates of the 2023 records are accurate, ''Bruhathkayosaurus'' may have rivaled the [[blue whale]] as one of the largest animals to ever exist.<ref name="Bruhathkayosaurus2023"/> However, all of the estimates are based on the dimensions of the fossils described in 1987, but these fossils have since disintegrated and no longer exist, making it impossible to affirm these estimates.<ref name="YadagiriAyyasami" /><ref name=":0" />

== Discovery and naming ==
{{Location map|India
|width = 225px
|coordinates={{coord|11.2|N|79.0|E|display=inline}}
|caption= ''Bruhathkayosaurus'' [[Type locality (biology)|type locality]] in Kallamedu village, [[Tiruchirappalli]] district, [[Tamil Nadu]], India
|pushpin_relief=1
}}
The [[holotype]] of ''Bruhathkayosaurus'', GSI PAL/SR/20, was discovered around 1978 near the southern tip of [[India]], specifically in the [[Tiruchirappalli]] district of [[Tamil Nadu]], northeast of Kallamedu village. It was recovered from rocks of the [[Kallamedu Formation]], which are dated to the [[Maastrichtian]] stage of the [[Late Cretaceous]], about 70 [[million years ago]]. The fossilized remains include [[hip]] bones (the [[ilium (bone)|ilium]] and [[ischium]]), partial leg bones ([[femur]] and [[tibia]]), a forearm ([[radius (bone)|radius]]) and a tail bone (part of a [[vertebra]], specifically a platycoelous caudal centrum). The remains were originally classified as belonging to a [[carnosauria]]n theropod by P. Yadagiri and K. Ayyasami in 1987 (not 1989, as some sources indicate).<ref name="YadagiriAyyasami">Yadagiri, P. and Ayyasami, K. (1987). "A carnosaurian dinosaur from the Kallamedu Formation (Maestrichtian horizon), Tamilnadu." In M.V.A. Sastry, V.V. Sastry, C.G.K. Ramanujam, H.M. Kapoor, B.R. Jagannatha Rao, P.P. Satsangi, and U.B. Mathur (eds.), ''Three Decades of Development in Palaeontology and Stratigraphy in India. Volume 1. Precambrian to Mesozoic. Geological Society of India Special Publication'', '''11'''(1): 523-528.</ref> The generic name chosen, "''Bruhathkayosaurus''", is derived from a combination of the [[Sanskrit]] word ''Bruhathkaya'' (''bṛhat'' {{lang|inc|[[:wikt:बृहत्|बृहत्]]}}, 'huge, heavy' and ''kāya'', काय 'body'), and the [[Ancient Greek|Greek]] ''sauros'' (lizard).<ref name=paulschneiderman>Schneiderman, P. (Nov 1994). "[http://dml.cmnh.org/1994Nov/msg00358.html Report on the initial description] {{Webarchive|url=https://web.archive.org/web/20131005002937/http://dml.cmnh.org/1994Nov/msg00358.html |date=5 October 2013 }}". ''Dinosaur Mailing List''</ref> The specific epithet, "''matleyi''", honours British palaeontologist [[Charles Alfred Matley]], who discovered many fossils in India.{{fact|date=February 2026}}

The [[monsoon]] season, combined with the sands and clays of the Kallamedu Formation, creates water-saturated fossils which are very [[Friability|friable]]. During the [[dry season]], expansion during the day and contraction during the night can cause fossils to split apart. This results in poorly preserved bones that can be impossible to extract without damage. In 2017, [[Peter Galton|Galton]] and Ayyasami reported that the ''Bruhathkayosaurus'' fossils started to disintegrate inside their field jackets before reaching the [[Geological Survey of India]] (GSI) and no longer exist.<ref name=":0">{{Cite journal|last1=Galton|first1=Peter M.|last2=Ayyasami|first2=Krishnan|date=1 July 2017|url=https://www.researchgate.net/publication/318428058|title=Purported latest bone of a plated dinosaur (Ornithischia: Stegosauria), a "dermal plate" from the Maastrichtian (Upper Cretaceous) of southern India|journal=Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen|language=en|volume=285|issue=1|pages=91–96|doi=10.1127/njgpa/2017/0671|bibcode=2017NJGPA.285...91G |issn=0077-7749}}</ref>

== Classification ==
''Bruhathkayosaurus'' was originally classified as a [[carnosauria]]n theropod (like ''[[Allosaurus]]''), of an uncertain position (''incertae sedis''). However, Chatterjee (1995) re-examined the remains and demonstrated that ''Bruhathkayosaurus'' is actually a [[titanosaur]] sauropod.<ref>Chatterjee, S. (1995). "The last dinosaurs of India". The Dinosaur Report, Fall 1995. p. 12-18.</ref> Some later studies listed ''Bruhathkayosaurus'' as an indeterminate sauropod or as a ''[[nomen dubium]]''.<ref>Upchurch, P., Barrett, P. M. and Dodson, P. 2004. Sauropoda. pp. 259–322. in Weishampel, D. B., Dodson, P. and Osmólska, H. (eds). The Dinosauria, Second Edition. University of California Press, Berkeley, 861 pp.</ref><ref name="krauseetal2006">{{cite journal |last1=Krause |first1=David W. |last2=O'Connor |first2=Patrick M. |last3=Rogers |first3=Kristina Curry |last4=Sampson |first4=Scott D. |last5=Buckley |first5=Gregory A. |last6=Rogers |first6=Raymond R. |title=Late Cretaceous terrestrial vertebrates from Madagascar: Implications for Latin American biogeography |journal=Annals of the Missouri Botanical Garden |date=23 August 2006 |volume=93 |issue=2 |pages=178–208 |doi=10.3417/0026-6493(2006)93[178:LCTVFM]2.0.CO;2 |s2cid=9166607 |url=https://www.biodiversitylibrary.org/part/390696 }}</ref><ref>{{Cite journal|last1=Hone|first1=David W. E.|last2=Farke|first2=Andrew A.|last3=Wedel|first3=Mathew J.|date=2016|title=Ontogeny and the fossil record: what, if anything, is an adult dinosaur?|journal=Biology Letters|language=en|volume=12|issue=2|article-number=20150947|doi=10.1098/rsbl.2015.0947 |pmc=4780552|pmid=26888916}}</ref>

The original publication described little in the way of diagnostic characteristics and was only supported by a few line drawings and photographs of the fossils as they lay in the ground. This led to online speculation by researchers that the bones might actually have been [[petrified wood]], akin to the way the original discoverers of ''[[Sauroposeidon]]'' initially believed their find to be [[fossil]]ized tree trunks.<ref name="Holtz1995a">Holtz, T. (1995), http://dml.cmnh.org/1995Sep/msg00701.html {{Webarchive|url=https://web.archive.org/web/20111111134307/http://dml.cmnh.org/1995Sep/msg00701.html |date=11 November 2011 }} "Re: Biggest predators"], discussion group, The Dinosaur Mailing List, 22 September 1995. Accessed 24 February 2019.</ref><ref name="mortimer2006">Mortimer, M. (2006), [http://dml.cmnh.org/2006Nov/msg00238.html "Re:"] {{Webarchive|url=https://web.archive.org/web/20111119191813/http://dml.cmnh.org/2006Nov/msg00238.html |date=19 November 2011 }}, discussion group, The Dinosaur Mailing List, 17 November 2006. Accessed 24 February 2019.</ref><ref name="Brusatte2001a">Brusatte, S. (2001), [http://dml.cmnh.org/2001Jun/msg00618.html "Re: Bruhathkayosaurus"] {{Webarchive|url=https://web.archive.org/web/20090107210722/http://dml.cmnh.org/2001Jun/msg00618.html |date=7 January 2009 }}, discussion group, The Dinosaur Mailing List, 18 June 2001. Accessed 24 February 2019.</ref> A 2022 review by Pal and Ayyasami presented additional previously unseen photographs of the tibia bone at the excavation site and in a plaster jacket, and reinforced the taxon's position within Titanosauria.<ref name=":2">{{Cite journal |last1=Pal |first1=Saurabh |last2=Ayyasami |first2=Krishnan |date=27 June 2022 |title=The lost titan of Cauvery |journal=[[Geology Today]] |language=en |volume=38 |issue=3 |pages=112–116 |doi=10.1111/gto.12390 |bibcode=2022GeolT..38..112P |s2cid=250056201 |issn=0266-6979}}</ref> However, as Dhananjay M. Mohabey and colleagues noted in 2024, "this new information has not resolved the identity of the element nor the validity of the taxon."<ref>{{Cite journal |last1=Mohabey |first1=Dhananjay M. |last2=Samant |first2=Bandana |last3=Vélez-Rosado |first3=Kevin I. |last4=Wilson Mantilla |first4=Jeffrey A. |date=7 February 2024 |title=A review of small-bodied theropod dinosaurs from the Upper Cretaceous of India, with description of new cranial remains of a noasaurid (Theropoda: Abelisauria) |journal=Journal of Vertebrate Paleontology |volume=43 |issue=3 |article-number=e2288088 |doi=10.1080/02724634.2023.2288088 |issn=0272-4634}}</ref>

==Size estimates==
According to the published description, the shin bone ([[tibia]]) of ''Bruhathkayosaurus'' was {{convert|2|m|ft|abbr=on}} long.<ref name="YadagiriAyyasami"/><ref name=":2"/> This is 29 percent larger than the fibula of ''[[Argentinosaurus]]'', which is only {{cvt|1.55|m|ft}} long. The fragmentary femur was similarly huge; across the distal end, it measured {{convert|75|cm|ft|abbr=on}}, 33% larger than the femur of ''[[Antarctosaurus|Antarctosaurus giganteus]]'', which measures {{convert|56|cm|ft|abbr=on}}. The ilium measured {{convert|1.2|m|ft|abbr=on}} in length.<ref name=":0"/><ref name="mortimer2004"/>

No total body size estimates for ''Bruhathkayosaurus'' have been published, but paleontologists and researchers have posted tentative estimates on the Internet. In a post from June 2001, Mickey Mortimer estimated that ''Bruhathkayosaurus'' could have reached {{convert|44.1|m|ft|||abbr=on}} in length and might have weighed {{convert|175|–|220|MT|ST|abbr=on}}, but in later posts retracted these estimates, reducing the estimated length to {{convert|28|–|47|m|ft|abbr=on}} based on more complete titanosaurs (''[[Saltasaurus]]'', ''[[Opisthocoelicaudia]]'' and ''[[Rapetosaurus]]''), and declined to provide a new weight estimate, describing the older weight estimates as inaccurate.<ref name="mortimer2001a">Mortimer, M. (2001), [http://dml.cmnh.org/2001Jun/msg00665.html "Re: Bruhathkayosaurus"] {{Webarchive|url=https://web.archive.org/web/20170522105714/http://dml.cmnh.org/2001Jun/msg00665.html |date=22 May 2017 }}, discussion group, The Dinosaur Mailing List, 19 June 2001. Accessed 23 May 2008.</ref><ref name="mortimer2004">Mortimer, M. (2004), [http://dml.cmnh.org/2004Sep/msg00086.html "Re: Largest Dinosaurs"] {{Webarchive|url=https://web.archive.org/web/20190913171408/http://dml.cmnh.org/2004Sep/msg00086.html |date=13 September 2019 }}, discussion group, The Dinosaur Mailing List, 7 September 2004. Accessed 23 May 2008.</ref><ref name="mortimer2001b">Mortimer, M. (2001), [http://dml.cmnh.org/2001Sep/msg00402.html "Titanosaurs too large?"] {{Webarchive|url=https://web.archive.org/web/20160303203315/http://dml.cmnh.org/2001Sep/msg00402.html |date=3 March 2016 }}, discussion group, The Dinosaur Mailing List, 12 September 2001. Accessed 23 May 2008.</ref> In a May 2008 article for the [[blog]] ''Sauropod Vertebra Picture of the Week'', paleontologist [[Matt Wedel]] used a comparison with ''Argentinosaurus'' and calculated the weight of ''Bruhathkayosaurus'' at up to {{convert|126|MT|ST|sp=us|lk=on|abbr=off}}.<ref name="wedel2008">Wedel, M. "[http://svpow.wordpress.com/2008/05/20/sv-pow-showdown-sauropods-vs-whales/ SV-POW! showdown: sauropods vs whales] {{Webarchive|url=https://web.archive.org/web/20120228092223/http://svpow.wordpress.com/2008/05/20/sv-pow-showdown-sauropods-vs-whales/ |date=28 February 2012 }}." [Weblog entry.] Sauropod Vertebra Picture of the Week. 20 May 2008. Accessed 23 May 2008.</ref> In 2019, [[Gregory S. Paul]] suggested that the supposed tibia was probably a degraded femur, in which case its length was slightly greater than that of ''[[Dreadnoughtus]]'' (1.91 meters) and ''[[Futalognkosaurus]]'' (1.98 meters). Its [[Ilium (bone)|ilium]] is similar in length to that of ''Dreadnoughtus'' whereas the width of the distal femur appears to slightly exceed that of ''[[Patagotitan]]''. Paul estimated its mass at around {{convert|30|–|55|MT|ST|abbr=on}}, much lower than any previous estimation.<ref name=":1">{{Cite journal|last=Paul|first=Gregory S.|date=2019|title=Determining the largest known land animal: A critical comparison of differing methods for restoring the volume and mass of extinct animals|url=http://www.gspauldino.com/Titanomass.pdf|journal=Annals of the Carnegie Museum|volume=85|issue=4|pages=335–358|doi=10.2992/007.085.0403|bibcode=2019AnCM...85..335P |s2cid=210840060|archive-url=https://web.archive.org/web/20220929122713/http://www.gspauldino.com/Titanomass.pdf|archive-date=29 September 2022|url-status=live}}</ref> In 2020, Molina-Perez and Larramendi suggested that the {{convert|2|m|ft|abbr=on}} long tibia is probably a [[fibula]], and estimated the size of the animal at {{convert|37|m|ft|abbr=on}} and {{convert|95|MT|ST|sp=us|lk=on|abbr=off}}.<ref>{{Cite book|last=Molina-Perez & Larramendi|title=Dinosaur Facts and Figures: The Sauropods and Other Sauropodomorphs|publisher=Princeton University Press|year=2020|location=New Jersey|page=263|bibcode=2020dffs.book.....M }}</ref>

By comparison, the titanosaur ''Argentinosaurus'' is estimated to have reached {{cvt|35|m|ft}} in length, and to have weighed 65–100 tonnes.<ref name=Paul1994>{{cite book |last=Paul |first=Gregory S. |date=Autumn 1994 |title=The Dinosaur Report |chapter=Big Sauropods - Really, Really Big Sauropods |pages=12–13 |publisher=The Dinosaur Society |chapter-url=http://gspauldino.com/DinoArtSauropods.pdf |access-date=14 November 2011 |archive-date=6 March 2012 |archive-url=https://web.archive.org/web/20120306221723/http://gspauldino.com/DinoArtSauropods.pdf |url-status=live }}</ref><ref name=":1" /><ref name=Paul1997>{{cite conference |last=Paul |first=Gregory S. |editor=Wolberg, D. L. |editor2=Stump, E. |editor3=Rosenberg, G. D. |year=1997 |book-title=DinoFest International Proceedings |title=Dinosaur models: the good, the bad, and using them to estimate the mass of dinosaurs |pages=129–154 |publisher=The Academy of Natural Sciences }}</ref> These sauropods are known only from partial or fragmentary remains, so the size estimates are uncertain. Length is calculated by comparing existing bones to the bones of similar dinosaurs, which are known from more complete skeletons and scaling them up isometrically. However, such extrapolation can never be more than an educated guess and the length of the tail, in particular, is often hard to judge. Determining mass is even more difficult because little evidence of soft tissues survives in the [[fossil record]]. In addition, [[Allometry#Isometric scaling and geometric similarity|isometric scaling]] is based on the assumption that body proportions remain the same, which is not necessarily the case. In particular, the proportions of the titanosaurs are not well known, due to a limited number of relatively complete specimens.<ref name="mortimer2004"/>

If the upper size estimates for ''Bruhathkayosaurus'' are accurate, it would even rival the size of the largest recorded [[blue whale]]. Mature blue whales can reach {{convert|30|m|ft|abbr=on}} in length, and the record-holder blue whale was recorded at {{convert|173|tonne|short ton|-1|lk=on|abbr=off}},<ref name="pop">{{cite web | title = Assessment and Update Status Report on the Blue Whale ''Balaenoptera musculus'' | publisher = Committee on the Status of Endangered Wildlife in Canada | year = 2002 | url = http://www.sararegistry.gc.ca/virtual_sara/files/cosewic/sr_blue_whale_e.pdf | access-date = 19 April 2007 | archive-date = 15 September 2014 | archive-url = https://web.archive.org/web/20140915084032/http://www.sararegistry.gc.ca/virtual_sara/files/cosewic/sr%5Fblue%5Fwhale%5Fe%2Epdf | url-status = live }}</ref> with estimates of up to {{convert|199|tonne|short ton|-1|lk=on|abbr=off}}.<ref>{{cite journal |last1=McClain |first1=Craig R. |last2=Balk |first2=Meghan A. |last3=Benfield |first3=Mark C. |last4=Branch |first4=Trevor A. |last5=Chen |first5=Catherine |last6=Cosgrove |first6=James |last7=Dove |first7=Alistair D.M. |last8=Gaskins |first8=Leo |last9=Helm |first9=Rebecca R. |last10=Hochberg |first10=Frederick G. |last11=Lee |first11=Frank B. |last12=Marshall |first12=Andrea |last13=McMurray |first13=Steven E. |last14=Schanche |first14=Caroline |last15=Stone |first15=Shane N. |last16=Thaler |first16=Andrew D. |title=Sizing ocean giants: patterns of intraspecific size variation in marine megafauna |journal=PeerJ |date=13 January 2015 |volume=3 |article-number=e715 |doi=10.7717/peerj.715 |pmid=25649000 |pmc=4304853 |doi-access=free }}</ref>

Another poorly known sauropod that shares similar size estimates to ''Bruhathkayosaurus'' is ''[[Maraapunisaurus|Maraapunisaurus fragillimus]]'', which is based on a now-missing dorsal vertebra. In 2006, [[Kenneth Carpenter]] used ''[[Diplodocus]]'' as a guide and estimated ''[[Maraapunisaurus]]'' to be {{convert|58|m|ft|abbr=on}} in length and weigh only about {{convert|122.4|MT|ST|sp=us|-1|lk=on|abbr=off}}.<ref name="carpenter2006">Carpenter, K. (2006). "Biggest of the big: a critical re-evaluation of the mega-sauropod ''Amphicoelias fragillimus''." In Foster, J.R. and Lucas, S.G., eds., 2006, ''Paleontology and Geology of the Upper Jurassic Morrison Formation''. New Mexico Museum of Natural History and Science Bulletin '''36''': 131–138.</ref> In 2018, however, Carpenter estimated ''Maraapunisaurus'' to be {{convert|30|-|32|m|ft|abbr=on}} in length based upon comparisons with rebbachisaurids.<ref>{{cite journal |last1=Carpenter |first1=Kenneth |title=Maraapunisaurus fragillimus, N.G. (formerly Amphicoelias fragillimus), a basal Rebbachisaurid from the Morrison Formation (Upper Jurassic) of Colorado |journal=Geology of the Intermountain West |date=19 October 2018 |volume=5 |pages=227–244 |doi=10.31711/giw.v5.pp227-244 |s2cid=210973474 |doi-access=free }}</ref> In 2019, Paul gave a higher estimation of {{convert|35|to|40|m|ft}} and a weight of {{convert|80|to|120|tonne|short ton}}.<ref name=":1" />

[[Gregory S. Paul|Paul]] and Larramendi (2023) suggested that ''Bruhathkayosaurus'' may have weighed within the range of {{convert|110|-|170|tonne|short ton}}, though they stated that it would have likely weighed between {{convert|110|and|130|tonne|short ton}}. Whilst its most liberal estimate was 240 tons when scaled with ''[[Patagotitan]]'', they considered any estimate over {{convert|170|tonne|short ton}} to be unlikely.<ref name="Bruhathkayosaurus2023">{{Cite journal |last1=Paul |first1=Gregory S. |last2=Larramendi |first2=Asier |date=11 April 2023 |title=Body mass estimate of ''Bruhathkayosaurus'' and other fragmentary sauropod remains suggest the largest land animals were about as big as the greatest whales |journal=Lethaia |language=en |volume=56 |issue=2 |pages=1–11 |doi=10.18261/let.56.2.5 |bibcode=2023Letha..56..2.5P |s2cid=259782734 |issn=0024-1164|doi-access=free }}</ref> Nevertheless, Paul stressed that the idea of these 'super-sauropods' or 'land-whales' aren't as far-fetched as one would think given the long period of sauropod existence as well as their very efficient body-plan (i.e. small heads, large body, efficient ventilated air-sacs, strong and flexible muscle and bone structure, and large source of static food), indicating that the existence of 150+ ton sauropods such as ''Bruhathkayosaurus'' and ''Maraapunisaurus'' are in the realm of possibility.<ref name="Bruhathkayosaurus2023"/>

== See also ==
* [[Largest prehistoric animals]]
* [[Largest and heaviest animals]]
* [[Dinosaur size]]
* ''[[Breviparopus]]''
* ''[[Patagotitan]]''

== References ==
{{Reflist|2}}

== External links ==
* [http://dml.cmnh.org/1994Nov/msg00358.html Report on the initial description] from the Dinosaur Mailing List

{{Sauropodomorpha|T.}}
{{Taxonbar|from=Q132867}}

[[Category:Titanosauria]]
[[Category:Dinosaur genera]]
[[Category:Maastrichtian dinosaurs]]
[[Category:Dinosaurs of India]]
[[Category:Fossil taxa described in 1987]]
[[Category:Taxa with lost type specimens]]

Bruhathkayosaurus - Revision history

BabulHossainjoy: creating a details - done