Nemegtosauridae

Nemegtosaurids Temporal range: Ma PreꞒ Ꞓ O S D C P T J K Pg N Possible Early Cretaceous record
Cast of the skull of Nemegtosaurus, on a mounted Opisthocoelicaudia skeleton, Museum of Evolution of Polish Academy of Sciences, Warsaw
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	Saurischia
Clade:	†Sauropodomorpha
Clade:	†Sauropoda
Clade:	†Macronaria
Clade:	†Titanosauria
Clade:	†Eutitanosauria
Superfamily:	†Saltasauroidea
Family:	†Nemegtosauridae Upchurch, 1995
Genera
†Nemegtosaurus †Quaesitosaurus †Tapuiasaurus?

Nemegtosauridae is a

Due to the diplodocid-like nature of the taxa placed in Nemegtosauridae, the systematic position of this family in Sauropoda was disputed until recently. McIntosh (1990) included both these animals in the family Diplodocidae, subfamily Dicraeosaurinae, as they resemble the skull of Dicraeosaurus, although differing in certain details. Although the skull of Nemegtosaurus was found in the same formation as the headless skeleton of Opisthocoelicaudia, McIntosh (1990) kept Nemegtosaurus in Diplodocoidea while keeping Opisthocoelicaudia separate from the former, a position reiterated by Upchurch (1995,^[5] 1999^[6]), and Upchurch et al. (2004). A cladistic analysis published in 2002 transferred Nemegtosaurus and Opisthocoelicaudia from Diplodocoidea to Titanosauria.^[1]

Apesteguia (2004), in a paper describing a new Patagonian sauropod, Bonitasaura salgadoi, may have been the first to properly define the taxon, although without the use of cladistic analysis: the stemclade consisting of all titanosaurs more closely related to Nemegtosaurus than to Saltasaurus. He argued for a close relationship between Nemegtosaurus, Quaesitosaurus, Rapetosaurus, and Bonitasaura and referred to the previous phylogenetic analysis and use of Nemegtosauridae by Wilson (2002).^[7]

In his redescription of the

In a paper discussing new anatomical data on the skull of Tapuiasaurus, Wilson and his colleagues cast doubt on the monophyly of Nemegtosauridae, judging from a rescoring of the Zaher et al. 2011 cladistic analysis regarding cranial characters. Tapuiasaurus was recovered as basal to Lithostrotia, rendering its position within Nemegtosauridae questionable.[11] A 2014 cladistic analysis gleaning new anatomical data from Diamantinasaurus also rendered Nemegtosauridae paraphyletic, with Rapetosaurus falling out as a member of Saltasauridae closer to Isisaurus than to Nemegtosaurus.^[12] The cladistic analysis of Patagotitan recovered Tapuiasaurus as the sister taxon of Rapetosaurus and Isisaurus but not Nemegtosaurus.^[13]

Nemegtosauridae was retained as a potentially useful clade of titanosaurs by Carballido and colleagues in 2022, who noted that it was either resolved as a small clade of titanosaurs, or an extensive group of taxa closer to Nemegtosaurus than Saltasaurus. Further work on the discovered postcrania was required to resolve the relationships of Nemegtosaurus and Opisthocoelicaudia, but it was preliminarily retained as a clade of saltasauroid that may end up as a synonym of Opisthocoelicaudiinae or even Lirainosaurinae.^[14]

Phylogeny

The cladogram below follows Zaher et al. (2011).^[15]

Lithostrotia	Malawisaurus Nemegtosauridae  Nemegtosaurus Rapetosaurus Tapuiasaurus Isisaurus Diamantinasaurus Saltasauridae  Opisthocoelicaudiinae  Alamosaurus Opisthocoelicaudia Saltasaurinae  Neuquensaurus Saltasaurus

References

1. ^
   doi:10.1046/j.1096-3642.2002.00029.x
   .
2. ^ McIntosh, J. S., 1990, "Sauropoda" in The Dinosauria, Edited by David B. Weishampel, Peter Dodson, and Halszka Osmólska. University of California Press, pp. 345–401.
3. ^ Upchurch, P., Barrett, P.M. and Dodson, P. 2004. Sauropoda. In The Dinosauria, 2nd edition. D. Weishampel, P. Dodson, and H. Osmólska (eds.). University of California Press, Berkeley. pp. 259–322.
4. ^ Re: Family Nemegtosauridae
5. doi:10.1098/rstb.1995.0125
   .
6. doi:10.1080/02724634.1999.10011127
   .
7. S2CID 33590452
   .
8. S2CID 54070651
   – via ResearchGate.
9. S2CID 4347583
   – via ResearchGate.
10. ISBN 0520246233
    .
11. hdl:2027.42/134419
    – via ResearchGate.
12. hdl:10044/1/27497
    – via ResearchGate.
13. PMID 28794222
    .
14. S2CID 248368302
    .
15. PMID 21326881.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )