Lessemsauridae

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Lessemsaurids
Temporal range:
Ma
Skeletal mount of Lessemsaurus
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: †Sauropodomorpha
Clade: †Sauropoda
Clade: †Lessemsauridae
Apaldetti et al., 2018
Genera

Lessemsauridae is a

node-based taxon, defined as all descendants of the most recent common ancestor of Lessemsaurus sauropoides and Antetonitrus ingenipes.[1] Depending on the definition of Sauropoda, Lessemsauridae is either one of the most basal sauropod taxa, or a sister taxon of Sauropoda. An additional member of the clade was named later in 2018, Ledumahadi.[2] A 2021 study by Pol and colleagues also assigned the genera Kholumolumo and Meroktenos to the group.[3]

Description

Lessemsaurids were quadrupeds. Unlike later sauropods, which had columnar limbs, the forelimbs of lessemsaurids were flexed.[2] Sauropodomorph trackways have been found with widely-spaced front feet, indicating they were made by a trackmaker with flexed forelimbs as in lessemsaurids.[4]

Lessemsaurids could reach large sizes, with Lessemsaurus estimated to have reached a mass of 7 tonnes[1] and the later Ledumahadi estimated to have reached a mass of 12 tonnes.[2]

They had highly pneumatic

dorsal vertebrae, very antero-posteriorly short but tall cervical vertebrae, robust cervicals, a very expanded distal scapula blade, and upright arms.[1][2]

Evolution and biogeography

Lessemsaurids first appeared during the middle Norian age of the Triassic. A specimen of an unnamed lessemsaurid from the Elliot Formation of South Africa probably dates to approximately 218 million years ago.[5] Lessemsaurus is a member of the La Esquina Local Fauna,[3] which probably dates to at least 213 million years ago.[6] Antetonitrus and Ledumahadi are found in the Upper Elliot Formation, which dates to the Hettangian and Sinemurian ages of the Jurassic.[7] Lessemsaurids are known from South Africa and Argentina.

References

  1. ^
    S2CID 49669597
    .
  2. ^
    PMID 30270189
    .
  3. ^
    S2CID 233579282
    .
  4. PMID 37790620
    .
  5. ^ Moopen, Atashni; Viglietti, Pia A; Choiniere, Jonah N (2023-12-15). "Anatomy and phylogenetic relationships of a possible lessemsaurid with associated plant fossils from the lower part of the Elliot Formation". Palaeontologia Africana. 56: 190–212.
  6. PMID 24843149
    .
  7. S2CID 225859330
    . Retrieved 2021-02-17.
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