Open Paleo

Australotitan

Hocknull et al., 2021 aw-STRAY-lo-TIE-tan /ɔːˈstreɪloʊˈtaɪtən/

From Latin 'australis' meaning 'southern' and Greek 'titan' meaning 'giant', referring to the large size of this dinosaur from southern Australia.

100.5–89.8 million years ago Cenomanian–Turonian, Late Cretaceous
Late Cretaceous stages

Australotitan is an extinct genus of possibly titanosaurian somphospondylan dinosaurs from the Late Cretaceous Winton Formation (Cenomanian-Turonian) of southern-central Queensland, Australia. The genus contains a single species, A. cooperensis, known from multiple partial skeletons. The genus Australotitan may be synonymous with Diamantinasaurus, a contemporary relative.

Under dispute

Australotitan is recovered within Diamantinasauria, where Beeston and colleagues (2024) found insufficient autapomorphies to distinguish it from Diamantinasaurus and suggested it is probably a junior synonym of Diamantinasaurus matildae, retaining it conservatively as an indeterminate diamantinasaurian.

Diagnosis

  1. Ulna with heavily reduced anterolateral and olecranon processes relative to much enlarged and elongate anteromedial process.
  2. Ulna with a distinct radial interosseous ridge within the distal half of the radial fossa, and anterolateral process bearing a distal accessory projection proximal to a proximally beveled distal epiphysis.
  3. Humerus with a rounded ridge extending from the distal end of the deltopectoral crest to just proximal of a tri-lobate distal epiphysis.
  4. Distal ischial blades curve ventrally to produce a dorsal face that is posteriorly directed.
  5. Femur with a medially sloped proximolateral margin, anteroposteriorly narrow diaphysis, and distal condyles directed anterolaterally to posteromedially.

Species

Australotitan cooperensis Hocknull et al., 2021

Type species

Named for the Cooper Creek system near the initial location of the holotype, and the nickname 'Cooper' given to the holotype when it was discovered.

Holotype
EMF102 , Eromanga Natural History Museum
Material
Ten appendicular elements: partial left scapula, partial left and complete right humerus, right ulna, right and left pubes and ischia, partial right and left femora, plus corticocancellous internal bone fragments.
Horizon
Winton Formation, Cenomanian–Turonian, Late Cretaceous , 100.5–89.8 million years ago
Locality
EML011(a), Plevna Downs Station, Queensland, Australia

Notable specimens

  • “George”

    EMF164 Eromanga Natural History Museum Found 2005 by Sandy Mackenzie largest individual

    Referred specimen representing the largest known individual; its 2.146 meter femur is the basis cited for Australotitan being the largest known Australian dinosaur, comparable to Futalognkosaurus and Dreadnoughtus. Preserves femur, ulna, vertebrae, and ribs.

    Hocknull et al. (2021)

References

  1. Hocknull, S. A.; Wilkinson, M.; Lawrence, R. A.; Konstantinov, V.; Mackenzie, S.; Mackenzie, R. (2021). A new giant sauropod, Australotitan cooperensis gen. et sp. nov., from the mid-Cretaceous of Australia. PeerJ 9: e11317. PeerJ. doi:10.7717/peerj.11317 hocknull2021a
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.

    Source of the body length, mass, and hip height estimates.

    jones2026b
  3. 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

    Found insufficient autapomorphies to distinguish Australotitan within Diamantinasauria.

    beeston2024a