''Menucocelsior'' (meaning "the taller one from Salitral Ojo del Agua") is a genus of medium-sized titanosaurian sauropod dinosaur from 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 ...

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, th ...

. The type and only species is ''Menucocelsior arriagadai''.

Discovery

The Salitral Ojo del Agua area of Río Negro, Argentina was home to an entire sauropod fauna during the late Cretaceous period. Fossil material belonging to saltasaurines, aeolosaurines, and other titanosaurs have been discovered. In 2022, Rolando ''et al.'' designated one specimen as the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

for a new titanosaurian taxon, ''Menucocelsior arriagadai.'' The generic name combines the

Mapudungun Mapuche (, Mapuche & Spanish: , or Mapudungun; from ' 'land' and ' 'speak, speech') is an Araucanian language related to Huilliche spoken in south-central Chile and west-central Argentina by the Mapuche people (from ''mapu'' 'land' and ''che ...

''menuco'', meaning "watering hole", a translation of Ojo del Agua, with the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

''celsior'', meaning "higher" or "major." The specific name honours "Beto" Arriagada, the owner of the ranch where the discoveries were made.

Description and classification

The

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 several ...

, MPCN-PV-798, consists of seventeen caudal vertebrae and several appendicular bones: a right humerus, a left fibula and some

metapodial Metapodials are long bones of the hand (metacarpals) and feet (metatarsal The metatarsal bones, or metatarsus, are a group of five long bones in the foot, located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes. ...

. The structure and form of these bones suggests it was a member of the

Eutitanosauria Eutitanosauria is a clade of titanosaurs, encompassing the more derived members of the group and characterized by the absence of the hyposphene-hypantrum articulation and possibly the presence of osteoderms. The group was first named by Sanz and c ...

, but not a member of the

Colossosauria Colossosauria is a clade of titanosaur sauropods from the latest Early Cretaceous through the Late Cretaceous of South America. The group was originally named by Bernardo González-Riga ''et al.'' in 2019 in paleontology, 2019 and defined as 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 ne ...

, or

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'', ...

. Fossil material suggests that ''Menucocelsior'' was about long.

Paleoecology

''Menucocelsior'' lived in the Allen Formation alongside a number of other titanosaurs, including the small saltasaurine ''

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 ...

'' and indeterminate saltasaurines and aeolosaurins, known from both skeletal remains and differing morphotypes of osteoderms. The describers note that such an assemblage of titanosaurs is not known anywhere else in the world; the titanosaurs' differing body plans probably allowed them to occupy differing

ecological niche In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of resources and competitors (for ...

s and thus limit competition.

References

Titanosaurs Late Cretaceous dinosaurs of South America Cretaceous Argentina Fossil taxa described in 2021 {{sauropodomorph-stub