''Overosaurus'' (meaning "Overo lizard", after the Cerro Overo locality) is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

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 ...

s, containing only a single species, ''Overosaurus paradasorum''. This species lived approximately 86 to 84 million years ago during the latter part of the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

Period Period may refer to: Common uses * Period (punctuation) * Era, a length or span of time *Menstruation, commonly referred to as a "period" Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (o ...

in what is now

Patagonia Patagonia () is a geographical region that includes parts of Argentina and Chile at the southern end of South America. The region includes the southern section of the Andes mountain chain with lakes, fjords, temperate rainforests, and glaciers ...

(in southern

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 ...

). ''Overosaurus paradasorum'' was relatively small compared to other sauropods from Patagonia, like the saltasaurids and other aeolosaurines, estimated as approximately . It was a ground-dwelling

herbivore A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat ...

Discovery and naming

The only known specimen of ''Overosaurus paradasorum'' was recovered at the Cerro Overo locality in

. The specimen was collected in 2002 by researchers from the Museo Carmen Funes, the Museo Argentino Urquiza, and the Natural History Museum of Los Angeles County, in terrestrial sediments deposited during 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 ...

stage of 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, approximately 84 to 78 million years ago. This specimen is housed in the collection of the Museo Argentino Urquiza in

Neuquén Neuquén (; ) is the capital city of the Argentine province of Neuquén and of the Confluencia Department, located in the east of the province. It occupies a strip of land west of the confluence of the Limay and Neuquén rivers which form t ...

, Argentina. The specimen was found by Carlos Parada and family, who provided logistic support to museum staff as well as assistance during fieldwork. The Cerro Overo locality was originally reported as within the

Anacleto Formation The Anacleto Formation is a geologic formation with outcrops in the Argentina, Argentine Patagonian provinces of Mendoza Province, Mendoza, Río Negro Province, Río Negro, and Neuquén Province, Neuquén. It is the youngest formation within the ...

of the

Neuquén Group The Neuquén Group is a geologic unit, group of geologic formations found in Argentina. Rocks in the Neuquén Group fall within the Cenomanian to early Campanian stages of the Late Cretaceous Period. It overlies the older Lohan Cura Formation and ...

, but is now attributed to the

Bajo de la Carpa Formation The Bajo de la Carpa Formation is a geologic formation of the Neuquén Basin that outcrop, crops out in northern Patagonia, in the provinces of Río Negro Province, Río Negro and Neuquén Province, Neuquén, Argentina. It is the oldest of two for ...

Description

''Overosaurus'' was described and named by Rodolfo A. Coria, Leonardo S. Filippi, Luis M. Chiappe, Rodolfo García and Andrea B. Arcucci in

2013 2013 was the first year since 1987 to contain four unique digits (a span of 26 years). 2013 was designated as: *International Year of Water Cooperation *International Year of Quinoa Events January * January 5 – 2013 Craig, Alask ...

. This species is known solely from 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 ...

MAU-Pv-CO-439 which consists of a fully articulated vertebral series from the 10th cervical to the 20th

caudal vertebra 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 ...

, the

rib In vertebrate anatomy, ribs () are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the thoracic cavity, enabling the lungs to expand and thus facilitate breathing by expanding the ...

s of the last three cervical vertebrae, six right dorsal ribs (articulated with their respective dorsal vertebrae 2,3,4,5,8,9), five left dorsal ribs (articulated with their respective dorsal vertebrae 2,3,4,5,8), the proximal portions of dorsal ribs of both sides of dorsal vertebrae 9 and 10, a complete right ilium and a fragmented left ilium. Specifically the vertebral series includes the last four cervical vertebrae, ten dorsal vertebrae, six sacral vertebrae, and twenty caudal vertebrae. Its sacrum consists of six fused sacral vertebrae.

Classification

''Overosaurus'' was differentiated from other

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 ...

taxa using a unique combination of characters present in the ilium and in the cervical, dorsal and caudal vertebrae. A

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

analysis of

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'' an ...

placed ''Overosaurus'' within the

Aeolosaurini Aeolosaurini is an extinct clade of titanosaurian dinosaurs known from the Cretaceous period of Argentina and Brazil. Rodrigo M. Santucci and Antonio C. de Arruda-Campos (2011) in their cladistic analysis found ''Aeolosaurus'', '' Gondwanatitan'' ...

, as the

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 a monophyletic group formed by '' Gondwanatitan faustoi'', '' Pitekunsaurus macayai'', ''

Aeolosaurus rionegrinus ''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. ''Aeolosau ...

'', and '' Aeolosaurus maximus''.

References

{{Portal bar, Argentina, Dinosaurs, Paleontology Lithostrotia Dinosaur genera Santonian dinosaurs Bajo de la Carpa Formation Taxa named by Rodolfo Coria Taxa named by Luis M. Chiappe Fossil taxa described in 2013 Dinosaurs of Argentina