Open Paleo

Diamantinasauria

Poropat et al., 2021

Its genera lived 113.2–89.8 million years ago Early Cretaceous–Late Cretaceous
Early Cretaceous and Late Cretaceous stages

Diamantinasauria is a clade of somphospondylan titanosauriform sauropods with close affinities to Titanosauria, known from the early Late Cretaceous of South America and Australia. It groups the Australian Diamantinasaurus, Savannasaurus, and Australotitan from the Winton Formation of Queensland with the Patagonian Sarmientosaurus of the Bajo Barreal Formation, and may also include Wintonotitan. This shared membership across two continents points to a faunal connection between Australia and South America by way of Antarctica during the Cretaceous. Distinguishing traits are drawn from the sternal plate, braincase, and limb skeleton, and dental microwear suggests these animals were mid-height browsers that fed on vegetation roughly one to ten meters above the ground. While the group is consistently recovered as a coherent clade, its exact position relative to Titanosauria has shifted between analyses.

Under dispute

The position of Diamantinasauria relative to Titanosauria is unstable. In equal-weights analyses, Poropat and colleagues (2016) recover Diamantinasaurus and Savannasaurus as non-lithostrotian titanosaurs, and Poropat and colleagues (2023) recover the named clade in the same position, whereas the most recent dedicated analyses recover the clade as the sister group to Titanosauria, just outside it (Beeston and colleagues, 2024, under both equal and extended implied weighting; Han and colleagues, 2024). It is placed conservatively as a non-titanosaurian somphospondylan following the most recent dedicated work.

Diagnosis

  1. Sternal plate D-shaped rather than reniform
  2. Absence of hyposphene-hypantrum articulations throughout the dorsal series
  3. Confluence of the spinopostzygapophyseal and centropostzygapophyseal fossae owing to loss of the intrapostzygapophyseal lamina
  4. Scapular blade bearing a fossa and a tuberosity on its medial surface near the acromion
  5. Ulna with a prominent interosseous ridge on the distal anterior surface

Genera placed directly in Diamantinasauria

  • Australotitan Hocknull et al., 2021 Cenomanian–Turonian (100.5–89.8 Ma)Australiaunder dispute
  • Diamantinasaurus Hocknull et al., 2009 Albian–Turonian (113.2–89.8 Ma)Australia
  • Sarmientosaurus Martínez et al., 2016 Cenomanian–Turonian (100.5–89.8 Ma)Argentinaunder dispute
  • Savannasaurus Poropat et al., 2016 Cenomanian–Turonian (100.5–89.8 Ma)Australia

References

  1. Poropat, S. F.; Kundrát, M.; Mannion, P. D.; Upchurch, P.; Tischler, T. R.; Elliott, D. A. (2021). Second specimen of the Late Cretaceous Australian sauropod dinosaur Diamantinasaurus matildae provides new anatomical information on the skull and neck of early titanosaurs. Zoological Journal of the Linnean Society 192: 610-674. doi:10.1093/zoolinnean/zlaa173 poropat2021a
  2. Poropat, S. F.; Mannion, P. D.; Upchurch, P.; Hocknull, S. A.; Kear, B. P.; Kundrát, M.; Tischler, T. R.; Sloan, T.; Sinapius, G. H. K.; Elliott, J. A.; Elliott, D. A. (2016). New Australian sauropods shed light on Cretaceous dinosaur palaeobiogeography. Scientific Reports 6(1). Springer Science and Business Media LLC. doi:10.1038/srep34467

    Described Savannasaurus; recovered it and Diamantinasaurus as non-lithostrotian titanosaurs, and Wintonotitan as a non-titanosaurian somphospondylan.

    poropat2016a
  3. Poropat, S. F.; Mannion, P. D.; Rigby, S. L.; Duncan, R. J.; Pentland, A. H.; Bevitt, J. J.; Sloan, T.; Elliott, D. A. (2023). A nearly complete skull of the sauropod dinosaur Diamantinasaurus matildae from the Upper Cretaceous Winton Formation of Australia and implications for the early evolution of titanosaurs. Royal Society Open Science 10(4): 221618. doi:10.1098/rsos.221618

    Equal-weights analysis recovers Diamantinasauria as a non-lithostrotian titanosaur clade near the base of Titanosauria, but outside Titanosauria under extended implied weighting.

    poropat2023a
  4. Han, F.; Yang, L.; Lou, F.; Sullivan, C.; Xu, X.; Qiu, W.; Liu, H.; Yu, J.; Wu, R.; Ke, Y.; Xu, M.; Hu, J.; Lu, P. (2024). A new titanosaurian sauropod, Gandititan cavocaudatus gen. et sp. nov., from the Late Cretaceous of southern China. Journal of Systematic Palaeontology 22(1): 2293038. Informa UK Limited. doi:10.1080/14772019.2023.2293038

    Recovers Diamantinasauria as sister taxon to Titanosauria rather than a sub-clade within it

    han2024a
  5. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.

    Places Diamantinasauria within Titanosauria as a likely early-branching group of Diamantinasaurus, Sarmientosaurus, Savannasaurus and Australotitan, reviewing its varied placements.

    jones2026b
  6. Beeston, S. L.; Poropat, S. F.; Mannion, P. D.; Pentland, A. H.; Enchelmaier, M. J.; Sloan, T.; Elliott, D. A. (2024). Reappraisal of sauropod dinosaur diversity in the Upper Cretaceous Winton Formation of Queensland, Australia, through 3D digitisation and description of new specimens. PeerJ 12: e17180. PeerJ. doi:10.7717/peerj.17180

    Recovered Diamantinasauria as the sister group of Titanosauria under both equal and extended implied weighting, with Sarmientosaurus as its earliest-diverging member.

    beeston2024a