''Lapparentosaurus'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

sauropod Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their b ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

from the Middle

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

. Its

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

s were found in

Madagascar Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...

(

Isalo III Formation The Isalo III Formation is a geological Formation (geology), formation in Madagascar, off the eastern coast of Africa. It dates back to the Middle Jurassic.Weishampel et al., 2004, pp.542-543 The use of the term "Isalo III" is somewhat controversia ...

). The type species is ''L. madagascariensis''.

Discovery and naming

In 1895

Richard Lydekker Richard Lydekker (; 25 July 1849 – 16 April 1915) was a British naturalist, geologist and writer of numerous books on natural history. He was known for his contributions to zoology, paleontology, and biogeography. He worked extensively in cata ...

named a new species of ''

Bothriospondylus ''Bothriospondylus'', from Ancient Greek βοθρίον (''bothríon''), meaning "trench", and σπόνδυλος (''spóndulos''), meaning "vertebra", is a nomen dubium, dubious genus of neosauropod sauropod dinosaur. It lived during the Late Ju ...

'', ''B. madagascariensis'' based on fossils found before 1894 by Joseph Thomas Last in the Majunga Basin in layers of the

Bathonian In the geologic timescale the Bathonian is an age (geology), age and stage (stratigraphy), stage of the Middle Jurassic. It lasted from approximately 168.2 ±1.2 annum, Ma to around 165.3 ±1.1 Ma (million years ago). The Bathonian Age succeeds ...

, the

. Because there was no real connection with this English form, in 1986 José Fernando Bonaparte named a separate genus. The

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

, the only known, is ''Lapparentosaurus madagascariensis''. The generic name honours

Albert-Félix de Lapparent Albert-Félix de Lapparent (; 1905–1975) was a French people, French Palaeontology, palaeontologist. He was also a Society of Saint-Sulpice, Sulpician priest. He undertook a number of fossil-hunting explorations in the Sahara desert. He contribute ...

. The

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

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'', described as the new genus ''

Narindasaurus ''Narindasaurus'' (meaning "Narinda Bay lizard") is a genus of Turiasauria, turiasaurian sauropod dinosaur from the Middle Jurassic Isalo III, Isalo III Formation of Madagascar. The type species, ''N. thevenini'' was formally described by Royo-Tor ...

'' in 2020. Age determination studies performed using growth ring counts suggest that this sauropod took 31–45 years to reach sexual maturity and was relatively fast-growing given the presence of a large amount of fibrolamellar bone.

Classification

The phylogenetic position of ''Lapparentosaurus'' was long poorly understood. It exhibits an unusual combination of characters of both basal and derived sauropods. It has been classified as a brachiosaurid or an indeterminate titanosauriform. However, recent phylogenetic analyses have shown it to be a basal eusauropod, not closely related to brachiosaurids at all. After many decades, Emilie Läng in 2008 recovered a traditional

Cetiosauridae Cetiosauridae is a family of sauropod dinosaurs which was first proposed by Richard Lydekker in 1888. While traditionally a wastebasket taxon containing various unrelated species, some recent studies have found that it may represent a natural cla ...

including ''Lapparentosaurus''.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). 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 ''Cetiosaurus'' ( meaning 'whale lizard', from the Greek '/ meaning 'sea monster' (later, 'whale') and '/ meaning 'lizard'), is a genus of herbivorous sauropod dinosaur from the Middle Jurassic Period, living about 171 to 165 million years ago ...

''. 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.

Gallery

All possible remains of ''Lapparentosaurus'': File:Lapparentosaurus madagascariensis teeth.jpg, Teeth File:Bothriospondylus madagascariensis caudal vertebrae.jpg, Caudal vertebrae Bothriospondylus madagascariensis 1.JPG, Limb bones Bothriospondylus madagascariensis.JPG, Metatarsals

References

{{Taxonbar, from=Q2154332 Sauropoda Dinosaur genera Bathonian dinosaurs Fossil taxa described in 1986 Taxa named by José Bonaparte Dinosaurs of Madagascar