''Pellegrinisaurus'' (meaning ''Lizard from Pelligrini'') is a genus of

titanosaurian Titanosaurs (or titanosaurians; members of the group Titanosauria) were a diverse group of sauropod dinosaurs, including genera from all seven continents. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still thr ...

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 ...

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 ...

that lived in

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the souther ...

during the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

period. The holotype was found in the

Allen Formation The Allen Formation is a geological formation in Argentina whose strata date back to the Late Cretaceous (middle Campanian to early Maastrichtian.Salgado et al., 2007 Dinosaur remains are among the fossils that have been recovered from the formati ...

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, t ...

Discovery and naming

ISS008-E-6023 Pellegrini Lake, Neuquén River

The assigned

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 seve ...

, MPCA 1500, was discovered in 1975 by Roberto Abel and his assistant Jaime Emilio Powell. It was recovered from the lower member of the

in the locality of

Pellegrini Lake The Pellegrini Lake is an artificial lake located on the Argentinian Patagonia, in the province of Río Negro, near the city of Cinco Saltos, at approximately and 270 m above mean sea level. This reservoir was originally a natural depressed are ...

, dating from the

Campanian The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campani ...

to lower

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interv ...

, but it was not formally described until 1996 by Leonardo Salgado. Initially, the recovered remains were referred to ''

Epachthosaurus ''Epachthosaurus'' (meaning "heavy lizard") was a genus of titanosaurian sauropod dinosaur from the Late Cretaceous. It was a basal lithostrotian titanosaur. Its fossils have been found in Central and Northern Patagonia in South America. Discove ...

'', but later this hypothesis was abandoned because MPCA 1500 did not share derived features with the holotype of ''Epachthosaurus''. The generic name ''Pellegrinisaurus'' refers to Pellegrini Lake, where the

specimen Specimen may refer to: Science and technology * Sample (material), a limited quantity of something which is intended to be similar to and represent a larger amount * Biological specimen or biospecimen, an organic specimen held by a biorepository ...

was found. The specific name ''powelli'' is in honour of Jaime E. Powell.

Description

''Pellegrinisaurus'' is a rather large

titanosaur Titanosaurs (or titanosaurians; members of the group Titanosauria) were a diverse group of sauropod dinosaurs, including genera from all seven continents. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still th ...

. It is estimated to have measured long and weighed . The holotype includes an incomplete right

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates wit ...

, twenty-six caudal and four dorsal

vertebrae The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristi ...

Autapomorphic In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or outgroup taxa, not even those most closely related to th ...

features of ''Pellegrinisaurus'', by which it can be distinguished, are: *The ventral side of the centrum of the dorsals has a transverse width equal to twice the dorsoventral (vertical) depth. *The mid-posterior and posterior caudals are anteroposteriorly (horizontally) elongated and have dorsoventrally depressed neural spines, the anterior ends of which are higher anteriorly than posteriorly. ''Pellegrinisaurus'' differs from other titanosaurs by having anteroposteriorly elongate and dorsoventrally depressed mid-posterior and posterior caudal spines; Salgado interpreted this condition as an extra- articulation between the

neural spine The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...

and the

articular process The articular processes or zygapophyses (Greek ζυγον = "yoke" (because it links two vertebrae) + απο = "away" + φυσις = "process") of a vertebra are projections of the vertebra that serve the purpose of fitting with an adjacent vertebr ...

of the subsequent vertebra, that reduced

tail The tail is the section at the rear end of certain kinds of animals’ bodies; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammals ...

movement. The right

is partially preserved. It is anteroposteriously compressed with a very flattened fourth

trochanter A trochanter is a Tubercle (human skeleton), tubercle of the femur near its joint with the hip bone. In humans and most mammals, the trochanters serve as important muscle attachment sites. Humans are known to have three trochanters, though the ...

. Laterally, it features a pronounced bulge similar to that of ''

Chubutisaurus ''Chubutisaurus'' (meaning "Chubut lizard") is a genus of dinosaur from the Early Cretaceous Period. It lived in South America. It is classified as a sauropod, specifically one of the titanosaurs. The type species, ''Chubutisaurus insignis'', wa ...

'', brachiosaurids and other titanosaurs.

Paleoecology

''Pellegrinisaurus'' was unearthed from the

, in which it probably lived alongside other titanosaurs, such as ''

Aeolosaurus ''Aeolosaurus'' (; "Aeolus' lizard") is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now South America. Like most sauropods, it would have been a quadrupedal herbivore with a long neck and tail. ''Aeolosa ...

'' and ''

Rocasaurus ''Rocasaurus'' (meaning " General Roca lizard") is a genus of titanosaurian sauropod that lived in South America. ''Rocasaurus'' was discovered in Argentina in 2000, within the Allen Formation which is dated to be middle Campanian to early Maastr ...

''. Salgado suggested that contemporaneous

hadrosaurids Hadrosaurids (), or duck-billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts. The ornithopod family, which inclu ...

and the titanosaur ''Aeolosaurus'' inhabited coastal lowlands while other larger titanosaurs (such as ''Pellegrinisaurus'') and

theropods Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally c ...

inhabited interior environments of the region.

Classification

Initially, Salgado placed ''Pellegrinisaurus'' as a possible

sister taxon In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

of the

Saltasaurinae Saltasaurinae is a subfamily of titanosaurian sauropods known from the late Cretaceous period of South America, India and Madagascar. Description Saltasaurines are relatively small sauropods with the general body shape of a small head, long n ...

, in view of the build of its vertebrae. Later, during the description of ''

Mansourasaurus ''Mansourasaurus'' (" Mansoura lizard") is a genus of herbivorous lithostrotian sauropod dinosaur from the Quseir Formation of Egypt. The type and only species is ''Mansourasaurus shahinae''. The discovery of ''Mansourasaurus'' was consider ...

'', Sallam ''et al.'' (2017) published a complete phylogenetic analysis of the

Titanosauria Titanosaurs (or titanosaurians; members of the group Titanosauria) were a diverse group of sauropod dinosaurs, including genera from all seven continents. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still thr ...

in which ''Pellegrinisaurus'' is found to be part of the clade

Lithostrotia Lithostrotia is a clade of derived titanosaur sauropods that lived during the Early Cretaceous and Late Cretaceous. The group was defined by Upchurch ''et al.'' in 2004 as the most recent common ancestor of '' Malawisaurus'' and '' Saltasaurus' ...

, in the Opisthocoelicaudiinae. During the redescription of ''Pellegrinisaurus'', phylogenetic analyses placed the taxon outside Saltasauridae, as a lithostrotian related to ''

Alamosaurus ''Alamosaurus'' (; meaning "Ojo Alamo lizard") is a genus of opisthocoelicaudiine titanosaurian sauropod dinosaurs, containing a single known species, ''Alamosaurus sanjuanensis'', from the late Cretaceous Period (geology), Period of what is now ...

'', ''

Baurutitan ''Baurutitan'' is a genus of sauropod dinosaur that lived during the Late Cretaceous in what is now Brazil. The type species, ''Baurutitan britoi'', was described in 2005 by Kellner and colleagues, although the fossil remains had already been di ...

'', and possibly ''

Nullotitan ''Nullotitan'' (meaning "Nullo's giant", in honor of paleontologist Francisco Nullo) is a genus of lithostrotian titanosaur from the Chorrillo Formation from Santa Cruz Province in Argentina. The type and only species is ''Nullotitan glaciaris'' ...

'' or ''

Trigonosaurus ''Trigonosaurus'' (meaning "triangle lizard" after Triangulo Mineiro, where it was found), is a genus of saltasaurid dinosaurs from the Maastrichtian Serra da Galga Formation of Brazil. The type species, ''Trigonosaurus pricei'', was first descr ...

''. The results are shown below, excluding relationships outside Lithostrotia.

References

{{Taxonbar, from=Q144074 Saltasaurids Late Cretaceous dinosaurs of South America Allen Formation Fossils of Argentina Cretaceous Argentina Fossil taxa described in 1996