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

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

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 ...

that lived in

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

during the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent 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 ''cre ...

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 forma ...

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

Discovery and naming

The assigned

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 ...

, 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 area ...

, 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. Campa ...

to lower

Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

, 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 Lithostrotia, lithostrotian titanosaur. Its fossils have been found in Central and Northern Patagonia in South Ame ...

'', 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 f ...

was found. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

''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 thr ...

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

femur The femur (; : femurs or femora ), or thigh bone is the only long bone, bone in the thigh — the region of the lower limb between the hip and the knee. In many quadrupeds, four-legged animals the femur is the upper bone of the hindleg. The Femo ...

, twenty-six caudal and four dorsal

vertebrae Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal ...

. Autapomorphic 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 Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal ...

and the

articular process The articular process or zygapophysis ( + apophysis) of a vertebra is a projection of the vertebra that serves the purpose of fitting with an adjacent vertebra. The actual region of contact is called the ''articular facet''.Moore, Keith L. et al. ...

of the subsequent vertebra, that reduced

tail The tail is the elongated section at the rear end of a bilaterian animal's body; in general, the term refers to a distinct, flexible appendage extending backwards from the midline of the torso. In vertebrate animals that evolution, evolved to los ...

movement. The right

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

trochanter A trochanter is a 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 have two, sometimes three, trochanters. Etymology The anatomical term ' ...

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

Chubutisaurus ''Chubutisaurus'' (meaning "Chubut lizard") is a genus of somphospondylan sauropod dinosaur from the Early Cretaceous Cerro Barcino Formation (Albian) of Argentina. The type species, ''Chubutisaurus insignis'', was described by del Corro in 197 ...

'',

brachiosaurids The Brachiosauridae ("arm lizards", from Greek ''brachion'' (βραχίων) = "arm" and ''sauros'' = "lizard") are a family or clade of herbivorous, quadrupedal sauropod dinosaurs. Brachiosaurids had long necks that enabled them to access the le ...

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 (geology), Period of what is now South America. Like most sauropods, it would have been a quadrupedal herbivore with a long neck an ...

'' 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 (), also hadrosaurs 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 fami ...

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

theropods Theropoda (; from ancient Greek , (''therion'') "wild beast"; , (''pous, podos'') "foot"">wiktionary:ποδός"> (''pous, podos'') "foot" is one of the three major groups (clades) of dinosaurs, alongside Ornithischia and Sauropodom ...

inhabited interior environments of the region.

Classification

''Pellegrinisaurus'' is a lithostrotian titanosaur, closely related to the North American genus ''

Alamosaurus ''Alamosaurus'' (; meaning "Ojo Alamo lizard") is a genus of titanosaurian sauropod dinosaurs containing a single known species, ''Alamosaurus sanjuanensis'', from the Maastrichtian age of the Late Cretaceous period in what is now southwestern ...

'', forming a clade that may also include ''

Dreadnoughtus ''Dreadnoughtus'' is a genus of titanosaurian sauropod dinosaur containing a single species, ''Dreadnoughtus schrani''. ''D. schrani'' is known from two partial skeletons discovered in Upper Cretaceous (Campanian to Maastrichtian; approximately ...

'', '' Nullotitan'', '' Baurutitan'', and '' Baurutitans possible synonym '' Trigonosaurus''. The clade containing ''Alamosaurus'' and ''Pellegrinisaurus'' has variously been found to either be closely related to, but outside,

Saltasauridae Saltasauridae (named after the Salta region of Argentina where they were first found) is a family of armored herbivorous sauropods from the Upper Cretaceous. They are known from fossils found in South America, Africa, Asia, North America, and Eur ...

, or as a member of Saltasauridae, within

Opisthocoelicaudiinae Opisthocoelicaudiinae is a subfamily of titanosaurian dinosaurs from the Late Cretaceous. It was named by John McIntosh in 1990. Opisthocoelicaudiines are known from Mongolia, Argentina, and the United States. Two genera were assigned to Opisthoc ...

. ''Alamosaurus'' and ''Pellegrinisaurus'' have also been considered possible members of

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 nec ...

, as Salgado originally proposed for ''Pellegrinisaurus'' when he named it.

References

{{Taxonbar, from=Q144074 Saltasauridae Dinosaur genera Maastrichtian dinosaurs Allen Formation Fossil taxa described in 1996 Dinosaurs of Argentina