''Arackar'' (meaning "skeleton" in

Kunza Kunza is an extinct language isolate once spoken in the Atacama Desert of northern Chile and southern Peru by the Atacama people, Atacama people, who have since shifted to Spanish people, Spanish. The last speaker was documented in 1949. Other n ...

) is an extinct genus of lithostrotian

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 ...

, possibly part of the

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, Asia, North America, and Europe. Th ...

, discovered in the Hornitos Formation of

Atacama Province Atacama Province ( es, Provinicia de Atacama) was one of the administrative divisions of Chile from 1843 to 1976. The capital was Copiapó. It was established on 31 October 1843 with its territory being carved out of the Province of Coquimbo. It w ...

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

. The genus contains a single species, ''Arackar licanantay'', described by Rubilar-Rogers ''et al.'' in 2021.

Discovery and naming

The holotype was discovered in 1993 at Quebrada La Higuera, approximately 75 km (47 mi) south of

Copiapó Copiapó () is a city and commune in northern Chile, located about 65 kilometers east of the coastal town of Caldera. Founded on December 8, 1744, it is the capital of Copiapó Province and Atacama Region. Copiapó lies about 800 km north ...

. The fossil material was briefly mentioned by Rubilar-Rogers & Gutstein in 2012 and was found to not be referable to the genus ''

Atacamatitan ''Atacamatitan'' (meaning "Atacama Desert titan") is a genus of titanosaurian sauropod dinosaurs that lived in South America during the Late Cretaceous period. Discovery and naming In February 2000, with the purpose of looking for Mesozoic ...

''. In 2021, ''Arackar licanantay'' was named and described by David Rubilar-Rogers, Alexander O. Vargas, Bernardo González Riga, Sergio Soto-Acuña, Jhonatan Alarcón-Muñoz, José Iriarte-Díaz, Carlos Arévalo and Carolina S. Gutstein. The holotype, SNGM-1, was found in a layer of the Hornitos Formation in

that dates back to 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'', the ...

period ( Campanian-

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 interval from ...

stages). It includes vertebrae of the neck and back, as well as a

humerus The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a roun ...

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 with ...

and

ischium The ischium () form ...

. It belonged to a

juvenile Juvenile may refer to: *Juvenile status, or minor (law), prior to adulthood *Juvenile (organism) *Juvenile (rapper) (born 1975), American rapper * ''Juvenile'' (2000 film), Japanese film * ''Juvenile'' (2017 film) *Juvenile (greyhounds), a greyho ...

and is currently the most complete specimen of a sauropod found in Chile. The full binomial name, ''Arackar licanantay,'' translates to "bones of the Atacamenians" in the

language.

Description

The holotype represents a small individual with a body length estimated at around long. The size of a fully grown ''Arackar'' is unknown. Some distinctive features have been identified by Ruilar-Rogers ''et al.''. The hollowing out between the front joint process and the vertebral body is high and wide. The hollowing out between the parapophysis and the lamina between the front joint process and the vertebral body extends over the entire front of the pedestal of the neural arch but not above the spinal canal. The posterior joint processes are narrower than the neural spine. The ridges between the neural spine and the posterior joint processes are reduced and shorter than the facet of the posterior joint process.

Classification

''Arackar'' was placed in the Titanosauria within the Lithostrotia in 2021, as a

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 t ...

of ''

Isisaurus ''Isisaurus'' (named after the Indian Statistical Institute) is a genus of titanosaurian dinosaur from the Late Cretaceous Lameta Formation of India. The genus contains a single species, ''Isisaurus colberti''. Discovery and Naming The type spe ...

''. Together, they form a sister

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

to '' Rapetosaurus'', within the Lithostrotia. The cladogram from Rubilar-Rogers ''et al.'' (2021) is shown below:

References

{{Taxonbar, from=Q105745562 Fossil taxa described in 2021 Titanosaurs Campanian first appearances Maastrichtian extinctions Late Cretaceous dinosaurs of South America