Lapparentosaurus

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Lapparentosaurus
Temporal range:
Ma
↓
Partial left femur
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: †Sauropodomorpha
Clade: †Sauropoda
Clade: †
Gravisauria
Clade: †Eusauropoda
Genus: †Lapparentosaurus
Bonaparte, 1986
Species:
†L. madagascariensis
Binomial name
†Lapparentosaurus madagascariensis
(Lydekker, 1895)
Synonyms

Lapparentosaurus is a

sauropod dinosaur from the Middle Jurassic. Its fossils were found in Madagascar (Isalo III Formation).[1]
The type species is L. madagascariensis.

Discovery and naming

In 1895

José Fernando Bonaparte named a separate genus.[2] The type species, the only known, is Lapparentosaurus madagascariensis. The generic name honours Albert-Félix de Lapparent. The holotype assigned by Bonaparte, MAA 91-92, consists of two neural arches. Much more abundant material has been referred, from at least three but perhaps as much as ten individuals from different growth stages. This includes vertebrae and limb elements but no skulls. The species is still lacking a good description and diagnosis. It should not be confused with ?Bothriospondylus madagascariensis, a distinct taxon now named Vouivria, or another distinct primitive sauropod from the Isalo III Formation once also referred to as "Bothriospondylus" madagascarensis,[3] described as the new genus Narindasaurus in 2020.[4]

Age determination studies performed using growth ring counts suggest that this sauropod took 31–45 years to reach sexual maturity[5] and was relatively fast-growing given the presence of a large amount of fibrolamellar bone.[6]

Classification

The phylogenetic position of Lapparentosaurus was long poorly understood. It exhibits an unusual combination of characters of both basal and derived sauropods.[7] It has been classified as a brachiosaurid or an indeterminate titanosauriform.[7] However, recent phylogenetic analyses have shown it to be a basal eusauropod, not closely related to brachiosaurids at all.[8] After many decades, Emilie Läng in 2008 recovered a traditional Cetiosauridae including Lapparentosaurus.[9] An in-depth revision in 2019 of the genus by Raveloson, Clark & Rasoamiaramana recovered a similar position with Lapparentosaurus being part of a paraphyletic Cetiosauridae, also including a multitude of similar Middle Jurassic cetiosaurids such as Chebsaurus, Ferganasaurus, and Cetiosaurus.[10] This position is supported by the presence of two autapomorphies common on both Lapparentosaurus and Cetiosaurus: a pyramid-shaped neural spine from the anterior dorsal vertebrae with tapering in shape or not flaring distally and loss of the spinodiapophyseal lamina on the dorsal vertebrae.[10]

Gallery

All possible remains of Lapparentosaurus:

  • Teeth
    Teeth
  • Teeth collected between 1934 and 1936
    Teeth collected between 1934 and 1936
  • Cervical vertebra
    Cervical vertebra
  • Caudal vertebrae
    Caudal vertebrae
  • Limb bones
    Limb bones
  • Metatarsals
    Metatarsals

References

  1. ^
    S2CID 128431891
    .
  2. ^ Bonaparte, J.F. (1986). "Les dinosaures (Carnosaures, Allosauridés, Sauropodes, Cétosauridés) du Jurassique Moyen de Cerro Cóndor (Chubut, Argentina)". Annales de Paléontologie (Vert.-Invert.). 72 (3): 325–386.
  3. doi:10.1111/j.1475-4983.2009.00919.x
    .
  4. doi:10.1093/zoolinnean/zlaa091
    .
  5. ^ de, Ricqlès (1983). "Cyclical growth in the long bones of a sauropod dinosaur". Acta Palaeontologica Polonica. 28: 225–232.
  6. ^ Rimblot-Baly, F.; de Ricqlès, A.; Zylberberg, L. (1995). "Analyse paléohistologique d'une série de croissance partielle chez Lapparentosaurus madagascariensis (Jurassique Moyen): essai sur la dynamique de croissance d'un dinosaure sauropode". Annales de Paléontologie. 81: 49–86.
  7. ^
    ISBN 0520254082
    .
  8. PMID 29085006
    .
  9. ^ Läng, E. (2008). Les Cétiosaures (Dinosaura, sauropoda) et les sauropodes du Jurassique moyen: revision systématique, nouvelles découvertes et implications phylogénétiques (Doctoral dissertation, Paris, Muséum national d'histoire naturelle).
  10. ^
    doi:10.3390/geosciences9120498
    .
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