Sauropodomorpha

Skeletal reconstruction of Massospondylus carinatus, copyright Ballista.

Belongs within: Dinosauria.
Contains: Plateosauridae, Massopoda.

The Sauropodomorpha are a clade of often large herbivorous dinosaurs, the best-known members of which are the gigantic sauropods. Non-sauropod sauropodomorphs are commonly referred to as ‘prosauropods’ though the majority of analyses have not recognised them as a monophyletic clade. The earliest sauropodomorphs, such as Saturnalia tupiniquim and Panphagia protos, are known from the Late Triassic (Carnian) of South America. These were small forms, close to 1.5 metres in length. Guaibasaurus candelariensis is a slightly larger form represented by a partial postcranial skeleton from the Norian of Brazil that has been placed by various analyses as either a basal sauropodomorph or basal theropod.

Synapomorphies (from Baron et al. 2017): Premaxilla with posterodorsal process thin, bar-like, restricted to ventral border of external naris; external naris extending posteriorly to overlie maxilla; anterior margin of external naris posterior to midlength of premaxillary body; posterior margin of external naris posterior to first maxillary alveolus; anterior profile of maxilla with a strong inflection (notch) at base of ascending ramus, creating an anterior ramus with parallel dorsal and ventral margins; squamosal with ventral process narrower than one-quarter of its length; ventral ramus of squamosal forming more than half of caudal border of lower temporal fenestra; 18 or more dentary teeth present; premaxillary teeth with crown at least moderately expanded above root; maxillary/dentary tooth serrations present as enlarged and coarser (lower density) denticles; majority of maxillary and dentary teeth not recurved; anterior dentary teeth inclined anteriorly (procumbent); ten or more cervical vertebrae present; cervical vertebrae lacking prezygaodiapophyseal lamina; preacetabular process triangular and pointed; ischial shaft distally expanded into distinct ‘foot’ or ‘boot’; tibia with posterolateral margin of distal end concave.

<==Sauropodomorpha [Plateosauria, Prosauropoda]
|--Pampadromaeus berberenaiBNB17, BM21
|--+--ChromogisaurusNS15
| `--Saturnalia Langer, Abdala et al. 1999BNB17, GU04
| `--S. tupiniquim Langer, Abdala et al. 1999GU04
`--+--Panphagia protosBNB17
`--+--Guaibasaurus Bonaparte, Ferigolo & Ribeiro 1999BM21, L04
| `--G. candelariensis Bonaparte, Ferigolo & Ribeiro 1999L04
`--+--Pantydraco caducusBM21, BNB17
`--+--Thecodontosaurus Riley & Stutchbury 1836BM21, GU04 [Thecodontosauridae]
| |--*T. antiquus Morris 1843Y03a
| |--T. caducus Yates 2003Y03a
| |--T. dubius Haughton 1924 (n. d.)GU04
| `--T. minor Haughton 1918 (n. d.)GU04
`--+--Efraasia Galton 1973BM21, GU04
| `--E. minor (Huene 1908) (see below for synonymy)Y03b
`--+--Plateosauravus Huene 1932BM21, GU04 [Plateosauravidae]
| `--*P. cullingworthi (Haughton 1924) (n. d.) [=Plateosaurus cullingworthi]GU04
`--+--Ruehleia Galton 2001BM21, GU04
| `--R. bedheimensis Galton 2001GU04
`--+--PlateosauridaeBM21
`--+--MassopodaBM21
`--+--Eucnemesaurus fortis Hoepen 1920 (n. d.)BM21, GU04 [=Euskelosaurus fortisD07]
`--Riojasaurus Bonaparte 1969BM21, GU04
`--R. incertus Bonaparte 1969GU04

Sauropodomorpha incertae sedis:
Avalonianus sanfordi (Seeley 1898) (n. d.)N85, H79 [=Avalonia sanfordiH79]
Dinosaurus (n. d.)N85
Nyasasaurus parringtoniBNB17
Orosauravus (n. d.)N85
Picrodon herveyi Seeley 1898 (n. d.)N85, H79
Thotobolosaurus (n. d.)N85
GresslyosaurusGU04
|--G. plieningeriAPS03
|--G. robustus Huene 1907-1908 (n. d.)GU04
`--G. torgeri Jaekel 1911 (n. d.)GU04
Aetonyx palustris Broom 1911 (n. d.)GU04
Dromicosaurus gracilis Hoepen 1920 (n. d.)GU04
Hortalotarsus skirtopodus Seeley 1894 (n. d.)GU04
Leptospondylus capensis Owen 1854 (n. d.)GU04
Pachysauriscus Kuhn 1959 (n. d.) [incl. Pachysaurops Huene 1959]GU04
`--*P. ajax (Huene 1907-1908) (n. d.) [=Pachysaurus ajax, *Pachysaurops ajax]GU04
Pachyspondylus orpenii Owen 1854 (n. d.)GU04
Yimenosaurus Bai, Yang & Wang 1990GU04
`--Y. youngi Bai, Yang & Wang 1990GU04
Fulengia Carroll & Galton 1977GU04, E88
`--F. youngi Carroll & Galton 1977 (n. d.)GU04
PachysaurusGU04
|--P. giganteus Huene 1932 (n. d.)GU04
|--P. magnus Huene 1907-1908 (n. d.)GU04
|--P. reiningeri Huene 1907-1908 (n. d.)GU04
`--P. wetzelianus Huene 1932 (n. d.)GU04
Palaeosaurus fraserianus Cope 1878 (n. d.)GU04
Strenusaurus procerus Bonaparte 1969 (n. d.)GU04
Tawasaurus minor Young 1982 (n. d.)GU04
‘Teratosaurus’ trossingensis Huene 1908 (n. d.)Y03b
Agrosaurus mcgillivrayi Seeley 1891GU04 [=Thecodontosaurus macgillivrayiV-RR99]
Basutodon ferox Huene 1932 (n. d.)N85, H79
Bagualosaurus agudoensisBM21
Buriolestes schultziBM21
Ngwevu intlokoiBM21
Asylosaurus yalensisP10

Efraasia minor (Huene 1908) [=Teratosaurus minor; incl. Palaeosaurus diagnosticus Huene 1932, *Efraasia diagnostica, Palaeosauriscus diagnosticus, Thecodontosaurus diagnosticus Fraas 1913 (n. n.), Sellosaurus fraasi Huene 1908]Y03b

*Type species of generic name indicated

References

[APS03] Allain, R., & X. Pereda Suberbiola. 2003. Dinosaurs of France. Comptes Rendus Palevol 2 (1): 27–44.

[BNB17] Baron, M. G., D. B. Norman & P. M. Barrett. 2017. A new hypothesis of dinosaur relationships and early dinosaur evolution. Nature 543: 501–506.

[BM21] Beccari, V., O. Mateus, O. Wings, J. Milàn & L. B. Clemmensen. 2021. Issi saaneq gen. et sp. nov.—a new sauropodomorph dinosaur from the Late Triassic (Norian) of Jameson Land, central east Greenland. Diversity 13: 561.

[D07] Dixon, D. 2007. The Complete Illustrated Encyclopedia of Dinosaurs & Prehistoric Creatures. Hermes House: London.

[E88] Evans, S. E. 1988. The early history and relationships of the Diapsida. In: Benton, M. J. (ed.) The Phylogeny and Classification of the Tetrapods vol. 1. Amphibians, Reptiles, Birds pp. 221–260. Clarendon Press: Oxford.

[GU04] Galton, P. M., & P. Upchurch. 2004. Prosauropoda. In: Weishampel, D. B., P. Dodson & H. Osmólska (eds) The Dinosauria 2nd ed. pp. 232–258. University of California Press: Berkeley.

[H79] Heerden, J. van. 1979. The morphology and taxonomy of Euskelosaurus (Reptilia: Saurischia; late Triassic) from South Africa. Navorsinge van die Nasionale Museum 4: 21–84.

[L04] Langer, M. C. 2004. Basal Saurischia. In: Weishampel, D. B., P. Dodson & H. Osmólska (eds) The Dinosauria 2nd ed. pp. 25–46. University of California Press: Berkeley.

[N85] Norman, D. 1985 (reprinted 2000). The Illustrated Encyclopedia of Dinosaurs. Salamander Books: London.

[NS15] Novas, F. E., L. Salgado, M. Suárez, F. L. Agnolin, M. D. Ezcurra, N. R. Chimento, R. de la Cruz, M. P. Isasi, A. O. Vargas & D. Rubilar-Rogers. 2015. An enigmatic plant-eating theropod from the Late Jurassic period of Chile. Nature 522: 331–334.

[P10] Paul, G. S. 2010. Dinosaurs: A Field Guide. A & C Black.

[V-RR99] Vickers-Rich, P., T. H. Rich, G. C. McNamara & A. Milner. 1999. Is Agrosaurus macgillivrayi Australia’s oldest dinosaur? Records of the Western Australian Museum Supplement 57: 191–200.

[Y03a] Yates, A. M. 2003a. A new species of the primitive dinosaur Thecodontosaurus (Saurischia: Sauropodomorpha) and its implications for the systematics of early dinosaurs. Journal of Systematic Palaeontology 1: 1–42.

[Y03b] Yates, A. M. 2003b. The species taxonomy of the sauropodomorph dinosaurs from the Löwenstein Formation (Norian, Late Triassic) of Germany. Palaeontology 46 (2): 317–337.

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