Abditosaurus

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Abditosaurus
Temporal range: Late Cretaceous, (Maastrichtian) 70.5  Ma
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Abditosaurus kuehnei.png
Life reconstruction of Abditosaurus kuehnei
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Sauropodomorpha
Clade: Sauropoda
Clade: Macronaria
Clade: Titanosauria
Clade: Lithostrotia
Family: Saltasauridae
Subfamily: Saltasaurinae
Genus: Abditosaurus
Vila et al., 2022
Species:
A. kuehnei
Binomial name
Abditosaurus kuehnei
Vila et al., 2022

Abditosaurus (meaning "forgotten lizard") is an extinct genus of titanosaurian sauropod dinosaur from the Late Cretaceous (Maastrichtian) Tremp Group of Catalonia, Spain. The type and only species is Abditosaurus kuehnei. Phylogenetic analyses recover it within a clade of South American and African saltasaurines, distinct from other insular dwarf sauropods from the European archipelago. Abditosaurus inhabited the Ibero-Armorican Island, a prehistoric island made up of what is now Spain, Portugal, and southern France, and would have been the largest titanosaur species in its environment. [1]

Contents

History of study

While prospecting for fossil mammals in 1954, German paleontologist Walter Georg Kühne on 25 September discovered the remains of a large titanosaur at the Orcau-1 locality of the Conques Formation of Catalonia, Spain. It was the first major sauropod find in Spain. During the initial two weeks of excavation Kühne managed to identify around ten bones, some of which were packaged and sent to the Instituto Lucas Mallada (ILM) in Madrid, while others remained at the site (jacketed for protection). Returning the following year, Kühne, alongside locals and researchers of the ILM, managed to identify ten more bones in addition to most of those left at the site. Like in 1954, some of the bones were transported to Madrid while the remainder were left at the site. These initial discoveries consisted of fragments of the ilium, parts of the scapula, dorsal vertebrae, chevrons, a tibia, parts of the femurs and a complete humerus alongside undetermined bones. Although Kühne asked for additional excavations, funding had run out and work at the locality was stopped. In 1956, the fossil material recovered was assigned by Albert-Félix de Lapparent and Emiliano Aguirre to a new, but unnamed, species of the now dubious genus Hypselosaurus . [2] It was not until 1984 and 1986 that additional expeditions to the area were conducted, helmed by Josep Vicenç Santafé of the Institut de Paleontologia de Sabadell, Barcelona, and assisted by researchers of the Institut d’Estudis Ilerdencs, Lleida. They identified a sternal plate and additional dorsal vertebrae. Another expedition was conducted from 2012 to 2014 by the Institut Català de Paleontologia, the University of Zaragoza and the Museu de la Conca Dellà. This expedition recovered elements left at the site by the 1955 and 1986 digs, with additional material of the limbs, tooth fragments, ribs and an articulated series of dorsal and cervical vertebrae. Subsequent research managed to discover some of the historical material. [1] In 2017, part of the initial finds were described. [3] This finding was shown in the 2017 documentary "Europe's Last Giant".

The type specimen, which has numerous accession numbers, is the most complete known European titanosaur skeleton, with the semi-articulated neck, preserving twelve of the estimated fourteen cervical vertebrae, being especially noteworthy. [4] Complete and nearly complete sequences of neck vertebrae are very rare in sauropods; as of early 2022, only 27 sauropod specimens with complete or nearly complete necks were known. [5] It was the first semi-articulated titanosaur specimen discovered in Europe. [6]

Etymology

In 2022, the type species Abditosaurus kuehnei was named and described by Bernat Vila, Albert Sellés, Miguel Moreno-Azanza, Novella L. Razzolini, Alejandro Gil-Delgado, José Ignacio Canudo and Àngel Galobart. The generic name, Abditosaurus, means "forgotten reptile", [7] and is derived from the Latin abditus, meaning "concealed," or "forgotten," as the fossil material was hidden for sixty years between the initial discovery and the last expedition that collected the last bones, and the Greek sauros, meaning "lizard". The specific name, kuehnei, honors Walter Georg Kühne, the discoverer of the type specimen. [1]

Description

Abditosaurus is noted for its large size, and is the largest titanosaur from the Ibero-Armorican Island, a geological region composing most of Spain and Southern France. [7] [4] It is estimated to have reached a length of 17.5 metres (57 ft) and mass of 14 tonnes (15 short tons). [1]

The holotype includes an ossified sternal rib and an ossified calcaneum, elements which hitherto had not been unequivocally identified in titanosaur specimens, leading to speculation that they had fully disappeared in the group. These bones probably ossified due to the advanced individual age of the holotype, which was also proven by its bone structure. [1]

Classification

Lognkosauria

Futalognkosaurus

Rukwatitan

Epachthosaurus

Mendozasaurus

Notocolossus

Atsinganosaurus

Saltasauridae
Opisthocoelicaudiinae

Mansourasaurus

Paludititan

Ampelosaurus

Lirainosaurus

Opisthocoelicaudia

Lohuecotitan

Pellegrinisaurus

Dreadnoughtus

Baurutitan

Alamosaurus

Saltasaurinae
Saltasaurini

Neuquensaurus

Saltasaurus

Maxakalisaurus

Paralititan

Abditosaurus

Phylogenetic position of Abditosaurus within Saltasauridae according to Vila et al. 2022. [1] European genera are highlighted in pink, showing that Abditosaurus is not closely related to other European titanosaurs.

Patagotitan

Maxakalisaurus

Paralititan

Baurutitan

Dreadnoughtus

Alamosaurus

Abditosaurus

Pellegrinisaurus

Mendozasaurus

Rukwatitan

Argentinosaurus

Futalognkosaurus

Notocolossus

Atsinganosaurus

Epachthosaurus

Saltasaurus

Neuquensaurus

Nemegtosaurus

Opisthocoelicaudia

Mansourasaurus

Paludititan

Ampelosaurus

Igai

Lirainosaurus

Lohuecotitan

Phylogenetic position of Abditosaurus within Eutitanosauria, after a 2023 analysis by Gorscak and colleagues, showing the results of their tip-dated Bayesian analysis [8]

The discoverers of Abditosaurus interpreted it as a member of Saltasaurinae, a clade of titanosaurs found in South America and Africa. Their phylogenetic analysis recovered the Egyptian sauropod Paralititan as the sister taxon of Abditosaurus, with the Brazilian Maxakalisaurus as their next-closest relative. The clade uniting these three species, in turn, formed a sister clade to Saltasaurini. As such, Abditosaurus is not closely related to other European sauropods, the majority of which were recovered as opisthocoelicaudiines by their phylogenetic analysis. [1] A subsequent study, using a revised version of the dataset used by Vila and colleagues, found Abditosaurus to occupy a different position, forming a clade with Alamosaurus , Pellegrinisaurus , Baurutitan , and Dreadnoughtus that was closely related to lognkosaurs. [8]

Paleoecology

The only known specimen of Abditosaurus was found in the Conques Formation, which dates to the early Maastrichtian age of the Cretaceous. At this time, southern France, Spain, and Portugal formed an island, known as the Ibero-Armorican Island. Most titanosaur taxa of the Ibero-Armorican Island, such as Lirainosaurus , Atsinganosaurus , Garrigatitan , Ampelosaurus , and Lohuecotitan , were small or medium-sized. In contrast, Abditosaurus was significantly larger and lacked physiological adaptations to an island environment, suggesting that the species was a recent arrival in the ecosystem. It may be part of a broader trend of larger sauropods replacing smaller endemic species in Europe during the early Maastrichtian, as larger sauropods first appear in the Hațeg biota around the same time. Abditosaurus is associated with eggs of the oospecies Fusioolithus baghensis , which closely resemble eggs found in Gondwana. [1]

Related Research Articles

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<i>Alamosaurus</i> Extinct genus of dinosaurs

Alamosaurus is a genus of opisthocoelicaudiine titanosaurian sauropod dinosaurs containing a single known species, Alamosaurus sanjuanensis, from the Maastrichtian age of the Late Cretaceous period in what is now southwestern North America. Isolated vertebrae and limb bones indicate that it reached sizes comparable to Argentinosaurus and Puertasaurus, which would make it the absolute largest dinosaur known from North America. Its fossils have been recovered from a variety of rock formations spanning the Maastrichtian age. Specimens of a juvenile Alamosaurus sanjuanensis have been recovered from only a few meters below the Cretaceous-Paleogene boundary in Texas, making it among the last surviving non-avian dinosaur species. Alamosaurus is the only known sauropod to have inhabited North America after their nearly 30-million year absence from the North American fossil record and probably represents an immigrant from South America.

<i>Aeolosaurus</i> Extinct genus of dinosaurs

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<i>Aralosaurus</i> Extinct genus of dinosaurs

Aralosaurus was a genus of hadrosaurid dinosaur that lived during the Late Cretaceous in what is now Kazakhstan. It is known only by a posterior half of a skull and some post-cranial bones found in the Bostobe Formation in rocks dated from the Upper Santonian-Lower Campanian boundary, at about 83.6 Ma. Only one species is known, Aralosaurus tuberiferus, described by Anatoly Konstantinovich Rozhdestvensky in 1968. The genus name means Aral Sea lizard, because it was found to the northeast of the Aral Sea. The specific epithet tuberiferus means bearing a tuber because the posterior part of the nasal bone rises sharply in front of the orbits like an outgrowth. Aralosaurus was originally reconstituted with a nasal arch similar to that of North American Kritosaurus. For many years, Aralosaurus was thus placed in the clade of the Hadrosaurinae. This classification was invalidated in 2004, following the re-examination of the skull of the animal which allowed to identify in Aralosaurus many typical characters of Lambeosaurinae. In particular, this study revealed that Aralosaurus had a hollow bony structure located far in front of the orbits, which communicated with the respiratory tract. This structure being broken at its base, its shape and size remains undetermined. More recently, Aralosaurus has been identified as the most basal Lambeosaurinae, and placed with its close relative Canardia from the upper Maastrichtian of France in the new clade of Aralosaurini.

<i>Ampelosaurus</i> Extinct genus of dinosaurs

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<i>Adamantisaurus</i> Extinct genus of dinosaurs

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<i>Pararhabdodon</i> Extinct genus of dinosaurs

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<i>Lirainosaurus</i> Extinct genus of reptiles

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<i>Gargantuavis</i> Extinct genus of birds

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<i>Atsinganosaurus</i> Extinct genus of dinosaurs

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<span class="mw-page-title-main">Saltasaurinae</span> Extinct subfamily of dinosaurs

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<i>Canardia</i> Extinct genus of dinosaurs

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<i>Sarmientosaurus</i> Extinct genus of dinosaurs

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Lohuecotitan is an extinct genus of titanosaurian sauropod dinosaur which lived during the Late Cretaceous in Spain. The only species known in the genus is Lohuecotitan pandafilandi, described and named in 2016.

<i>Austroposeidon</i> Extinct genus of dinosaurs

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<i>Adynomosaurus</i> Extinct genus of dinosaurs

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<span class="mw-page-title-main">Saltasaurini</span> Extinct tribe of reptiles

Saltasaurini is a tribe of titanosaur sauropods known from the Late Cretaceous of Patagonia, Argentina. The clade was named in 2007 by Leonardo Salgado and José Bonaparte for the "least inclusive clade comprising Neuquensaurus and Saltasaurus", being equivalent to the use of Saltasaurinae in Salgado et al. (1997). Found only in the Campanian to Maastrichtian sediments of the Neuquén Basin, Salgado & Bonaparte (2007) decided a more restrictive clade was needed because of the expansion of Saltasaurinae as defined to include far more taxa than it originally encompassed. Saltasaurini includes the original core of Saltasaurinae: Neuquensaurus, Saltasaurus, Rocasaurus and Bonatitan, although some studies exclude Bonatitan from the clade.

<i>Tamarro</i> Genus of troodontid dinosaur from the Late Cretaceous period

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References

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