Lessemsaurus

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title: "Lessemsaurus" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["anchisauria", "dinosaur-genera", "norian-dinosaurs", "los-colorados-formation", "fossil-taxa-described-in-1999", "taxa-named-by-josé-bonaparte", "dinosaurs-of-argentina"] description: "Sauropodomorph dinosaur genus from Late Triassic Argentina" topic_path: "geography/argentina" source: "https://en.wikipedia.org/wiki/Lessemsaurus" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Sauropodomorph dinosaur genus from Late Triassic Argentina ::

| name = Lessemsaurus | fossil_range = mid-Norian ~ | image = Lessemsaurus Senckenberg.jpg | image_caption = Reconstructed skeleton | genus = Lessemsaurus | parent_authority = Bonaparte 1999 | species = sauropoides | authority = Bonaparte 1999

Lessemsaurus is an extinct genus of sauropodiform dinosaur that lived in the Norian-aged (Upper Triassic) Los Colorados Formation of what is now Argentina.

Naming and description

The type species, L. sauropoides, was formally described by José Fernando Bonaparte in 1999 in honor of Don Lessem, a writer of popular science books. It was found in the Los Colorados Formation of the Ischigualasto-Villa Unión Basin in La Rioja Province, Argentina.

It is part of the La Esquina faunal assemblage, dating to the mid-Norian stage, around 213 million years ago. It is estimated to have reached 10 - long and weighed over 7 MT, possibly up to 8 -, in maximum body mass.

Classification

::figure[src="https://upload.wikimedia.org/wikipedia/commons/a/ad/Lessemsaurus_mount.jpg" caption="Exhibit in Singapore"] ::

A cladogram after Pol, Garrido & Cerda, 2011, illustrates a possible placing of Lessemsaurus and Antetonitrus in Sauropodomorpha: |label1=Sauropodomorpha |1={{clade |1=Saturnalia |2={{clade |1={{clade |1=Pantydraco |2=Thecodontosaurus }} |2={{clade |1=Efraasia |2={{clade |1=Ruehleia |2=Plateosaurus |label3=Massopoda |3={{clade |1=Riojasaurus |2={{clade |1={{clade |1=Massospondylus |2={{clade |1=Coloradisaurus |2=Lufengosaurus |3=Gyposaurus |4=Yunnanosaurus }} }} |label2=Anchisauria |2={{clade |1=Anchisaurus |2={{clade |1=Aardonyx |2={{clade |1=Leonerasaurus |2={{clade |1=Melanorosaurus |label2=Sauropoda |2={{clade |1={{clade |1=Antetonitrus |2=Lessemsaurus }} |2={{clade |1=Kotasaurus |2={{clade |1=Vulcanodon |2=Eusauropoda }} }} }} }} }} }} }} }} }} }} }} }} }} }}

In 2018, Apaldetti et al. recovered it as part of a clade they named Lessemsauridae, after Lessemsaurus. Their cladogram is reproduced below:

|label1=Sauropodiformes |1={{clade |1=Mussaurus |2={{clade |1=Aardonyx |2=Sefapanosaurus |3={{clade |1={{clade |label1=Melanorosauridae |1={{clade |1=Camelotia |2=Melanorosaurus }} }} |2={{clade |label1=Sauropoda |1={{clade |1={{clade |label1=Lessemsauridae |1={{clade |1=Antetonitrus |2={{clade |1=Ingentia |2=Lessemsaurus }} }} }} |2={{clade |1=Blikanasaurus |2={{clade |1=Gongxianosaurus |2={{clade |1=Pulanesaura |2=Gravisauria }} }} }} }} }} }} }} }} }}

The following cladogram shows the position of Lessemsaurus outside of Sauropoda, according to Oliver W. M. Rauhut and colleagues, 2020:

|label1=Massopoda |1={{clade |1={{clade |1=Eucnemesaurus |2=Riojasaurus [[File:Riojasaurus sketch3.jpg|80px]] |2={{clade |1=Sarahsaurus |2={{clade |label1=Massospondylidae |1={{clade |1={{clade |1=Yunnanosaurus |2={{clade |1=Jingshanosaurus [[File:Jingshanosaurus xinwaensis.png|80px]] |2=Seitaad |2={{clade |1={{clade |1=Coloradisaurus |2={{clade |1=Glacialisaurus [[File:Glacialisaurus2.jpg|80px]] |2=Lufengosaurus |2={{clade |1=Massospondylus [[File:Massospondylus reconstruction.png|80px]] |2={{clade |1=Adeopapposaurus |2=Leyesaurus |label2=Sauropodiformes |2={{clade |1=Xingxiulong |2={{clade |1={{clade |1=Anchisaurus |2=Leonerasaurus [[File:Leonerasaurus NT.jpg|80px]] |2={{clade |1=Mussaurus [[File:Mussaurus patagonicus life restoration.png|80px]] |2={{clade |1=Aardonyx |2={{clade |1=Sefapanosaurus |2={{clade |1=Meroktenos |2={{clade |1=Melanorosaurus |2={{clade |1=Camelotia |2={{clade |1={{clade |1=Lessemsaurus |2={{clade |1=Antetonitrus [[File:Antetonitrus reconstruction.jpg|80px]] |2=Ingentia |2={{clade |1=Blikanasaurus |2={{clade |1=Pulanesaura |2={{clade |1=Gongxianosaurus |2={{clade |1=Schleitheimia |2={{clade |1=Isanosaurus |2={{clade |1=Tazoudasaurus |2=Sauropoda [[File:Diplodocus carnegii (flipped, cropped).jpg|80px]]

References

References

1. Weishampel, David B; ''et al.'', 2004. "Dinosaur distribution (Late Triassic, South America)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 527–528. {{ISBN. 0-520-24209-2.
2. Bonaparte, J. F.. (1999). "Evolución de las vértebras presacras en Sauropodomorpha". [[Ameghiniana]].
3. (2007). "New information on ''Lessemsaurus sauropoides'' (Dinosauria: Sauropodomorpha) from the Upper Triassic of Argentina". Special Papers in Palaeontology.
4. Kent, Dennis V.. (2018-06-12). "Empirical evidence for stability of the 405-kiloyear Jupiter–Venus eccentricity cycle over hundreds of millions of years". Proceedings of the National Academy of Sciences.
5. Diego Pol. (2011). "A New Sauropodomorph Dinosaur from the Early Jurassic of Patagonia and the Origin and Evolution of the Sauropod-type Sacrum". PLOS ONE.
6. (2011). "Die Saurier in Frick". Mitteilungen der aargauischen Naturforschenden Gesellschaft.
7. (2018). "An early trend towards gigantism in Triassic sauropodomorph dinosaurs". Nature Ecology & Evolution.
8. (2018). "A giant dinosaur from the earliest Jurassic of South Africa and the transition to quadrupedality in early sauropodomorphs". Current Biology.
9. Diego Pol. (2011). "A New Sauropodomorph Dinosaur from the Early Jurassic of Patagonia and the Origin and Evolution of the Sauropod-type Sacrum". PLOS ONE.
10. (2018). "An early trend towards gigantism in Triassic sauropodomorph dinosaurs". Nature Ecology & Evolution.
11. (2020). "A derived sauropodiform dinosaur and other sauropodomorph material from the Late Triassic of Canton Schaffhausen, Switzerland". [[Swiss Journal of Geosciences]].

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