Nemegtosauridae

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Nemegtosaurids
Temporal range: Late Cretaceous, 75–66  Ma
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Possible Early Cretaceous record
Opisthocoelicaudia Museum of Evolution in Warsaw 14.JPG
Cast of the skull of Nemegtosaurus, on a mounted Opisthocoelicaudia skeleton, Museum of Evolution of Polish Academy of Sciences, Warsaw
Scientific classification OOjs UI icon edit-ltr.svg
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

Nemegtosauridae is a family of titanosaurian sauropod dinosaurs based on their diplodocid-like skulls. [1] [2] [3] Only three species are known: [4] Nemegtosaurus , Quaesitosaurus and possibly Tapuiasaurus , each from the Cretaceous.

History of classification

Skull reconstruction of Tapuiasaurus Tapuiasaurus skull reconstruction.png
Skull reconstruction of Tapuiasaurus

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]

Skull reconstruction of Nemegtosaurus Nemegtosaurus skull reconstruction.png
Skull reconstruction of Nemegtosaurus

In his redescription of the Nemegtosaurus holotype, Wilson (2005) elaborated on the titanosaurian nature of Nemegtosaurus, defining Nemegtosauridae as a stem-based clade that includes all titanosaurs more closely related to Nemegtosaurus than to Saltasaurus . He also suggested that Opisthocoelicaudia may eventually be shown to be a junior synonym of Nemegtosaurus. [8] For her part, Kristina Curry Rogers (see also Cuury Rogers and Forster [2001] [9] ) agreed with Wilson that both Nemegtosaurus and Quaesitosaurus were titanosaurs rather than diplodocoids, but rejected the validity of Nemegtosauridae and the clade concepts given under that name. Quaesitosaurus was placed in the Saltasaurinae and Nemegtosaurus in a new, unnamed " Rapetosaurus clade" (which, under ICZN rules, would, if named, be termed subfamily Nemegtosaurinae or tribe Nemegtosaurini, depending on its position). Opisthocoelicaudia was placed in a separate clade, the Opisthocoelicaudiinae. All three clades are included in the Saltasauridae (= Titanosauridae). [10]

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

Skull material of Tapuiasaurus Tapuiasaurus.png
Skull material of Tapuiasaurus

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

Lithostrotia 

Related Research Articles

<span class="mw-page-title-main">Titanosauria</span> Extinct clade of dinosaurs

Titanosaurs were a diverse group of sauropod dinosaurs, including genera from all seven continents. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still thriving at the time of the extinction event at the end of the Cretaceous. This group includes some of the largest land animals known to have ever existed, such as Patagotitan—estimated at 37 m (121 ft) long with a weight of 69 tonnes —and the comparably-sized Argentinosaurus and Puertasaurus from the same region.

<i>Quaesitosaurus</i> Extinct genus of reptiles

Quaesitosaurus is a genus of nemegtosaurid sauropod containing only the type species, Q. orientalis, described in 1983. It lived from 72 to 71 million years ago during the Late Cretaceous epoch in the Barun Goyot Formation. With long, low and horse-like with frontally located peg-teeth, the skull of Quaesitosaurus is similar enough to the skull of Diplodocus and its kin to have prompted informed speculation that the missing body was built like those of diplodocids.

<i>Antarctosaurus</i> Sauropod dinosaur genus from Late Cretaceous

Antarctosaurus is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now South America. The type species, Antarctosaurus wichmannianus, and a second species, Antarctosaurus giganteus, were described by prolific German paleontologist Friedrich von Huene in 1929. Three additional species of Antarctosaurus have been named since then but later studies have considered them dubious or unlikely to pertain to the genus.

Agustinia is a genus of sauropod dinosaur from the Early Cretaceous of South America. The genus contains a single species, Agustinia ligabuei, known from a single specimen that was recovered from the Lohan Cura Formation of Neuquén Province in Argentina. It lived about 116–108 million years ago, in the Aptian–Albian stages of the Early Cretaceous Period.

<i>Bonitasaura</i> Extinct genus of dinosaurs

Bonitasaura is a genus of titanosaurian dinosaur hailing from uppermost layers of the Late Cretaceous (Santonian) Bajo de la Carpa Formation, Neuquén Group of the eastern Neuquén Basin, located in Río Negro Province, Northwestern Patagonia, Argentina. The remains, consisting of a partial sub-adult skeleton jumbled in a small area of fluvial sandstone, including a lower jaw with teeth, a partial vertebrae series, and limb bones, were described by Sebastian Apesteguía in 2004.

<i>Nemegtosaurus</i> Sauropod dinosaur genus from Late Cretaceous Period

Nemegtosaurus was a sauropod dinosaur from the Late Cretaceous Period of what is now Mongolia. It was named after the Nemegt Basin in the Gobi Desert, where the remains — a single skull — were found. The skull resembles diplodocoids in being long and low, with pencil-shaped teeth. However, recent work has shown that Nemegtosaurus is in fact a titanosaur, closely related to animals such as Saltasaurus, Alamosaurus and Rapetosaurus.

<i>Opisthocoelicaudia</i> Sauropod dinosaur genus from Late Cretaceous Mongolia

Opisthocoelicaudia is a genus of sauropod dinosaur of the Late Cretaceous Period discovered in the Gobi Desert of Mongolia. The type species is Opisthocoelicaudia skarzynskii. A well-preserved skeleton lacking only the head and neck was unearthed in 1965 by Polish and Mongolian scientists, making Opisthocoelicaudia one of the best known sauropods from the Late Cretaceous. Tooth marks on this skeleton indicate that large carnivorous dinosaurs had fed on the carcass and possibly had carried away the now-missing parts. To date, only two additional, much less complete specimens are known, including part of a shoulder and a fragmentary tail. A relatively small sauropod, Opisthocoelicaudia measured about 11.4–13 m (37–43 ft) in length. Like other sauropods, it would have been characterised by a small head sitting on a very long neck and a barrel shaped trunk carried by four column-like legs. The name Opisthocoelicaudia means "posterior cavity tail", alluding to the unusual, opisthocoel condition of the anterior tail vertebrae that were concave on their posterior sides. This and other skeletal features lead researchers to propose that Opisthocoelicaudia was able to rear on its hindlegs.

<i>Andesaurus</i> Extinct genus of dinosaurs

Andesaurus is a genus of basal titanosaurian sauropod dinosaur which existed during the middle of the Cretaceous Period in South America. Like most sauropods, belonging to one of the largest animals ever to walk the Earth, it would have had a small head on the end of a long neck and an equally long tail.

<i>Isisaurus</i> Extinct genus of dinosaurs

Isisaurus is a genus of titanosaurian dinosaur from the Late Cretaceous Lameta Formation of India and Pab Formation of Pakistan. The genus contains a single species, Isisaurus colberti.

<span class="mw-page-title-main">Saltasauridae</span> Extinct family of dinosaurs

Saltasauridae is a family of armored herbivorous sauropods from the Upper Cretaceous. They are known from fossils found in South America, Africa, Asia, North America, and Europe. They are characterized by their vertebrae and feet, which are similar to those of Saltasaurus, the first of the group to be discovered and the source of the name. The last and largest of the group and only one found in North America, Alamosaurus, was thirty-four metres in length and one of the last sauropods to go extinct.

<span class="mw-page-title-main">Lithostrotia</span> Extinct clade of dinosaurs

Lithostrotia is a clade of derived titanosaur sauropods that lived during the Early Cretaceous and Late Cretaceous. The group was defined by Upchurch et al. in 2004 as the most recent common ancestor of Malawisaurus and Saltasaurus and all the descendants of that ancestor. Lithostrotia is derived from the Ancient Greek lithostros, meaning "inlaid with stones", referring to the fact that many known lithostrotians are preserved with osteoderms. However, osteoderms are not a distinguishing feature of the group, as the two noted by Unchurch et al. include caudal vertebrae with strongly concave front faces (procoely), although the farthest vertebrae are not procoelous.

Malarguesaurus is a genus of titanosauriform sauropod dinosaur from the Late Cretaceous of Mendoza Province, Argentina. Its fossils, consisting of tail vertebrae, chevrons, ribs, and limb bones, were found in the upper Turonian-lower Coniacian Portezuelo Formation of the Neuquén Group. The type species, described by González Riga et al. in 2008, is M. florenciae.

<i>Diamantinasaurus</i> Extinct genus of reptiles

Diamantinasaurus is a genus of titanosaurian sauropod from Australia that lived during the early Late Cretaceous, about 94 million years ago. The type species of the genus is D. matildae, first described and named in 2009 by Scott Hocknull and colleagues based on fossil finds in the Winton Formation. Meaning "Diamantina lizard", the name is derived from the location of the nearby Diamantina River and the Greek word sauros, "lizard". The specific epithet is from the Australian song Waltzing Matilda, also the locality of the holotype and paratype. The known skeleton includes most of the forelimb, shoulder girdle, pelvis, hindlimb and ribs of the holotype, and one shoulder bone, a radius and some vertebrae of the paratype.

<span class="mw-page-title-main">Opisthocoelicaudiinae</span> Extinct clade of dinosaurs

Opisthocoelicaudiinae is a subfamily of titanosaurian dinosaurs from the Late Cretaceous. It was named by John McIntosh in 1990. Opisthocoelicaudiines are known from Mongolia, Argentina, and the United States. Two genera were assigned to Opisthocoelicaudiinae by Gonzalez et al. (2009): Alamosaurus and Opisthocoelicaudia, a conclusion also found by Díez Díaz et al. (2018). The hands of opisthocoelicaudiines lacked wrist bones and phalanges.

<i>Tapuiasaurus</i> Extinct species of reptile

Tapuiasaurus is a genus of titanosaur which lived during the Lower Cretaceous period in what is now Minas Gerais, Brazil.

<span class="mw-page-title-main">Aeolosaurini</span> Extinct clade of dinosaurs

Aeolosaurini is an extinct clade of titanosaurian dinosaurs known from the Cretaceous period of Argentina and Brazil. Rodrigo M. Santucci and Antonio C. de Arruda-Campos (2011) in their cladistic analysis found Aeolosaurus, Gondwanatitan, Maxakalisaurus, Panamericansaurus and Rinconsaurus to be aeolosaurids.

<span class="mw-page-title-main">Saltasaurinae</span> Extinct subfamily of dinosaurs

Saltasaurinae is a subfamily of titanosaurian sauropods known from the late Cretaceous period of South America, India and Madagascar.

<i>Patagotitan</i> Extinct genus of dinosaurs

Patagotitan is a genus of titanosaurian sauropod dinosaur from the Cerro Barcino Formation in Chubut Province, Patagonia, Argentina. The genus contains a single species known from at least six young adult individuals, Patagotitan mayorum, which was first announced in 2014 and then named in 2017 by José Carballido and colleagues. Preliminary studies and press releases suggested that Patagotitan was the largest known titanosaur and land animal overall, with an estimated length of 37 m (121 ft) and an estimated weight of 69 tonnes. Later research revised the length estimate down to 31 m (102 ft) and weight estimates down to approximately 50–57 tonnes, suggesting that Patagotitan was of a similar size to, if not smaller than, its closest relatives Argentinosaurus and Puertasaurus. Still, Patagotitan is one of the most-known titanosaurs, and so its interrelationships with other titanosaurs have been relatively consistent in phylogenetic analyses. This led to its use in a re-definition of the group Colossosauria by Carballido and colleagues in 2022.

<span class="mw-page-title-main">Colossosauria</span> Extinct clade of dinosaurs

Colossosauria is a clade of titanosaur sauropods from the latest Early Cretaceous through the Late Cretaceous of South America. The group was originally named by Bernardo González-Riga et al. in 2019 and defined as the "most inclusive clade containing Mendozasaurus neguyelap but not Saltasaurus loricatus or Epachthosaurus sciuttoi". The clade contains different taxa depending on the phylogenetic analysis used, in the defining paper the only subgroups were Rinconsauria and Lognkosauria, but alternate phylogenies published previously had also included various similar titanosaurs such as Aeolosaurus, Bonitasaura, Drusilasaura, Overosaurus and Quetecsaurus. The phylogenetic analysis of González-Riga et al. (2019) placed Colossosauria as sister taxa to Epachthosaurus, Pitekunsaurus and a larger clade including Saltasauridae.

<i>Igai</i> Extinct genus of sauropod dinosaurs

Igai is a genus of titanosaur from the Late Cretaceous Quseir Formation of Kharga Oasis, Egypt. The type species is Igai semkhu.

References

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  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. Upchurch, P (1995). "The evolutionary history of sauropod dinosaurs" (PDF). Philosophical Transactions of the Royal Society of London B. 349 (1330): 365–390. Bibcode:1995RSPTB.349..365U. doi:10.1098/rstb.1995.0125.
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  15. Hussam Zaher, Diego Pol, Alberto B. Carvalho, Paulo M. Nascimento, Claudio Riccomini, Peter Larson, Rubén Juarez-Valieri, Ricardo Pires-Domingues, Nelson Jorge da Silva Jr., Diógenes de Almeida Campos (2011). "A Complete Skull of an Early Cretaceous Sauropod and the Evolution of Advanced Titanosaurians". PLOS ONE. 6 (2): e16663. Bibcode:2011PLoSO...616663Z. doi: 10.1371/journal.pone.0016663 . PMC   3034730 . PMID   21326881.{{cite journal}}: CS1 maint: multiple names: authors list (link)