Open Paleo

Lessemsauridae

Apaldetti et al., 2018 Type genus Lessemsaurus

Its genera lived 227.3–192.9 million years ago Late Triassic–Early Jurassic
Late Triassic and Early Jurassic stages

Lessemsauridae is a clade of early sauropodiform dinosaurs that lived from the Late Triassic into the Early Jurassic of Gondwana, with fossils known from Argentina, South Africa, and possibly Lesotho. It unites Lessemsaurus, Antetonitrus, and Ingentia, with Ledumahadi added shortly afterward and the genera Kholumolumo and Meroktenos later assigned to the group as well. Its members were quadrupeds among the first dinosaurs to reach truly large size, with Lessemsaurus estimated near 7 tonnes and Ledumahadi near 12. Unlike the columnar-limbed sauropods that followed, lessemsaurids retained somewhat flexed forelimbs, and they are further marked by highly pneumatic neck and back vertebrae, short but tall and robust cervicals, and a broadly expanded shoulder blade. Sitting on the boundary between sauropodiforms and true sauropods, the group is recovered either as the most basal sauropods or as their immediate sister lineage depending on how Sauropoda is defined.

Under dispute

Lessemsauridae (Lessemsaurus, Antetonitrus, Ingentia, Ledumahadi) sits on the Sauropodiformes-Sauropoda boundary, and whether it falls inside or just outside Sauropoda is definition-dependent: under the stem-based Sauropoda of Yates (2007), the most inclusive clade containing Saltasaurus but not Melanorosaurus, it is the basalmost sauropod clade, whereas under the more restrictive node-based definition of Salgado and colleagues (1997), adopted by McPhee and colleagues (2014), it is the immediate non-sauropodan sister group of Sauropoda.

Diagnosis

  1. Dorsoventrally tall, transversely expanded ("plate-like") dorsal neural spines
  2. Slit-shaped neural canals on the dorsal vertebrae
  3. Massive, broad scapular blade

Genera placed directly in Lessemsauridae

  • Antetonitrus Yates & Kitching, 2003 Hettangian–Sinemurian (201.4–192.9 Ma)South Africa
  • Ingentia Apaldetti et al., 2018 Norian–Rhaetian (227.3–201.4 Ma)Argentina
  • Ledumahadi McPhee et al., 2018 Hettangian–Sinemurian (201.4–192.9 Ma)South Africa
  • Lessemsaurus Bonaparte, 1999 Norian (227.3–205.7 Ma)Argentina

References

  1. Apaldetti, C.; Martínez, R. N.; Cerda, I. A.; Pol, D.; Alcober, O. (2018). An early trend towards gigantism in Triassic sauropodomorph dinosaurs. Nature Ecology & Evolution 2(8): 1227-1232. Springer Science and Business Media LLC. doi:10.1038/s41559-018-0599-y

    Erected Lessemsauridae.

    apaldetti2018a
  2. Yates, A. M. (2007). Solving a dinosaurian puzzle: the identity of Aliwalia rex Galton. Historical Biology 19(1): 93-123. doi:10.1080/08912960600866953

    Defined Sauropoda as the most inclusive clade containing Saltasaurus loricatus but not Melanorosaurus readi.

    yates2007a
  3. McPhee, B. W.; Yates, A. M.; Choiniere, J. N.; Abdala, F. (2014). The complete anatomy and phylogenetic relationships of Antetonitrus ingenipes (Sauropodiformes, Dinosauria): implications for the origins of Sauropoda. Zoological Journal of the Linnean Society 171(1): 151-205. doi:10.1111/zoj.12127

    Redescribed Antetonitrus and recovered it as the sister taxon of Lessemsaurus, adopting the node-based Sauropoda of Salgado and colleagues (1997).

    mcphee2014a
  4. Salgado, L.; Coria, R. A.; Calvo, J. O. (1997). Evolution of titanosaurid sauropods. I: phylogenetic analysis based on the postcranial evidence. Ameghiniana 34: 3-32.

    Defined Sauropoda as the most recent common ancestor of Vulcanodon karibaensis and Eusauropoda and all its descendants.

    salgado1997a
  5. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.

    Treats Lessemsauridae as a distinct early branch of sauropods including Lessemsaurus, Antetonitrus, Ledumahadi, Ingentia and possibly Blikanasaurus.

    jones2026b