''Lapparentosaurus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

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 bo ...

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

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 Mya. The J ...

. 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 preserved ...

s were found in

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

(

Isalo III Formation The Isalo III Formation is a geological 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 controversial as the two prior u ...

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

Discovery and naming

In 1895

Richard Lydekker Richard Lydekker (; 25 July 1849 – 16 April 1915) was an English naturalist, geologist and writer of numerous books on natural history. Biography Richard Lydekker was born at Tavistock Square in London. His father was Gerard Wolfe Lydekker, ...

named a new species of ''

Bothriospondylus ''Bothriospondylus'' ("excavated vertebra") is a dubious genus of neosauropod sauropod dinosaur. It lived during the Late Jurassic. Discovery and naming The type species, ''Bothriospondylus suffossus'', was described by Richard Owen in 1875. The ...

'', ''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 and stage of the Middle Jurassic. It lasted from approximately 168.3 Ma to around 166.1 Ma (million years ago). The Bathonian Age succeeds the Bajocian Age and precedes the Callovian Age. Strat ...

, the

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

type species In 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 species that contains the biological type specimen ...

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

Albert-Félix de Lapparent Albert-Félix de Lapparent (1905–1975) was a French palaeontologist. He was also a Sulpician priest. He undertook a number of fossil-hunting explorations in the Sahara desert. He contributed greatly to our knowledge of dinosaurs and other prehist ...

. The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

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 ''Vouivria'' is a genus of herbivorous sauropod dinosaur, belonging to the Brachiosauridae, that lived in the area of present France during the Late Jurassic. The type species is ''Vouivria damparisensis''. History In 1926, the Solvay company ...

,'' 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 "lizard of Narinda Bay") is a genus of turiasaurian sauropod dinosaur from the Middle Jurassic Isalo III Formation of Madagascar. The type species, ''N. thevenini'' was formally described by Royo-Torres ''et al.'' in 2 ...

'' 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 c ...

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 ''Chebsaurus'' is a genus of quadrupedal, herbivorous, cetiosaurid sauropod dinosaur, specifically a eusauropod. It lived in present-day Algeria, in the Callovian aged Aïssa Formation. The type species, ''C. algeriensis'', was named in 2005 b ...

'', '' 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 168 million years ago in what ...

''. 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 Bothriospondylus madagascariensis francia teeth.JPG, Teeth collected between 1934 and 1936 Bothriospondylus madagascariensis francia cervical vertebra.JPG, Cervical vertebra File:Bothriospondylus madagascariensis caudal vertebrae.jpg, Caudal vertebrae Bothriospondylus madagascariensis 1.JPG, Limb bones Bothriospondylus madagascariensis.JPG, Metatarsals

References

Cetiosauridae Macronarians Dinosaurs of Madagascar Middle Jurassic sauropods Sauropods of Africa Middle Jurassic dinosaurs of Africa Bathonian genera Fossils of Madagascar Fossil taxa described in 1986 Taxa named by José Bonaparte {{Sauropodomorph-stub