''Elaltitan'' 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 ...

of large

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 ...

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 ...

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 ...

known from 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 ...

(mid

Cenomanian The Cenomanian is, in the International Commission on Stratigraphy's (ICS) geological timescale, the oldest or earliest age (geology), age of the Late Cretaceous epoch (geology), Epoch or the lowest stage (stratigraphy), stage of the Upper Cretace ...

Turonian The Turonian is, in the International Commission on Stratigraphy, ICS' geologic timescale, the second age (geology), age in the Late Cretaceous epoch (geology), Epoch, or a stage (stratigraphy), stage in the Upper Cretaceous series (stratigraphy), ...

stage) of

Chubut Province Chubut ( from Tehuelche language, Tehuelche 'transparent'; ) is a provinces of Argentina, province in southern Argentina, situated between the 42nd parallel south (the border with Río Negro Province), the 46th parallel south (bordering Santa ...

, 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 ...

. It contains a single species, ''Elaltitan lilloi''.

Etymology

''Elaltitan'' was first described and named by Philip D. Mannion and Alejandro Otero in

2012 2012 was designated as: *International Year of Cooperatives *International Year of Sustainable Energy for All Events January *January 4 – The Cicada 3301 internet hunt begins. * January 12 – Peaceful protests begin in the R ...

and the

type species In International_Code_of_Zoological_Nomenclature, 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 spe ...

is ''Elaltitan lilloi''. The generic name is derived from ''Elal'' (pronounced as "ee-lal") - the god of the

Tehuelche people The Tehuelche people, also called the Aónikenk, are an Indigenous people from eastern Patagonia in South America. In the 18th and 19th centuries the Tehuelche were influenced by Mapuche people, and many adopted a horseriding lifestyle. Once a ...

and ''

titan Titan most often refers to: * Titan (moon), the largest moon of Saturn * Titans, a race of deities in Greek mythology Titan or Titans may also refer to: Arts and entertainment Fictional entities Fictional locations * Titan in fiction, fictiona ...

'', giant in

Greek mythology Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and a genre of ancient Greek folklore, today absorbed alongside Roman mythology into the broader designation of classical mythology. These stories conc ...

. 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 ...

, ''lilloi'', honors Miguel Lillo, for his contribution and legacy to natural sciences in Tucumán.

Discovery

''Elaltitan'' is known only from a single individual, represented by an associated partial

postcranial The postcranium ("behind the cranium"; plural: postcrania) or postcranial skeleton in zoology and vertebrate paleontology is the skeleton apart from the skull. The postcranium encompasses the axial skeleton, which includes the entirety of the verte ...

skeleton A skeleton is the structural frame that supports the body of most animals. There are several types of skeletons, including the exoskeleton, which is a rigid outer shell that holds up an organism's shape; the endoskeleton, a rigid internal fra ...

. 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 ...

includes both PVL 4628 and MACN-CH 217 comprising three

dorsal vertebrae In vertebrates, thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. In humans, there are twelve thoracic vertebra (anatomy), vertebrae of intermediate size between the ce ...

, two

caudal vertebrae Caudal vertebrae are the vertebrae of the tail in many vertebrates. In birds, the last few caudal vertebrae fuse into the pygostyle, and in apes, including humans, the caudal vertebrae are fused into the coccyx. In many reptiles, some of the caud ...

, left

scapula The scapula (: scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on either side ...

, left

humerus The humerus (; : humeri) 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 (bone), radius and ulna, and consists of three sections. The humeral upper extrem ...

, left

radius In classical geometry, a radius (: radii or radiuses) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The radius of a regular polygon is th ...

, both ulnae, right pubis, proximal half of 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 ...

, distal part of left

tibia The tibia (; : tibiae or tibias), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two Leg bones, bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outsi ...

, distal two-thirds of left

fibula The fibula (: fibulae or fibulas) or calf bone is a leg bone on the lateral side of the tibia, to which it is connected above and below. It is the smaller of the two bones and, in proportion to its length, the most slender of all the long bones. ...

, right

astragalus Astragalus may refer to: * ''Astragalus'' (plant), a large genus of herbs and small shrubs *Astragalus (bone) The talus (; Latin for ankle or ankle bone; : tali), talus bone, astragalus (), or ankle bone is one of the group of foot bones known ...

and

calcaneum In humans and many other primates, the calcaneus (; from the Latin ''calcaneus'' or ''calcaneum'', meaning heel; : calcanei or calcanea) or heel bone is a bone of the tarsus of the foot which constitutes the heel. In some other animals, it is t ...

. ''Elaltitan'' is the first titanosaur skeleton to preserve an associated calcaneum. Although all of the material was originally housed in the Colección de Paleontología de Vertebrados de la Fundación Instituto Miguel Lillo in Tucumán, Argentina and accessioned as PVL 4628, the dorsal vertebrae and complete caudal vertebra were subsequently moved to the Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” in Buenos Aires, where they were accessioned as MACN-CH 217. The holotype specimen was collected by an expedition of the Fundación Miguel Lillo and the Universidad Nacional de Tucumán, led by José Fernando Bonaparte, from the right (southern) bank of the

Senguerr River The Senguerr River is a river of the Argentine province of Chubut. It begins its journey from the system of glacial lakes La Plata and Fontana in the Andes Mountains. The river flows generally eastward, then circles around the southern end of the ...

, in the area between the bend of this river and the Pampa de María Santísima, southeast of the southernmost part of the Sierra de San Bernardo,

. It came from the lower member of the

Bajo Barreal Formation The Bajo Barreal Formation is a geological Formation (geology), formation in the Golfo San Jorge Basin of Chubut Province, Chubut and Santa Cruz Province, Argentina, Santa Cruz, Argentina whose strata date back to the Cenomanian, Middle Cenomanian ...

, dating to the middle

to the

stage of 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 ...

, about 96.5-89.3

million years ago Million years ago, abbreviated as Mya, Myr (megayear) or Ma (megaannum), is a unit of time equal to (i.e. years), or approximately 31.6 teraseconds. Usage Myr is in common use in fields such as Earth science and cosmology. Myr is also used w ...

Description

The

of ''Elaltitan'' was originally attributed to ''

Antarctosaurus ''Antarctosaurus'' (; meaning "southern lizard") is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Period (geology), Period of what is now South America. The type species, ''Antarctosaurus wichmannianus'', and a second speci ...

sp.'' by Bonaparte & Gasparini (1979), and later tentatively referred to '' Argyrosaurus'' by Jaime Powell (1986, 2003). Philip D. Mannion and Alejandro Otero (2012), who named the genus, diagnosed ''Elaltitan'' by a unique combination of characters, as well as one

autapomorphy In phylogenetics, an autapomorphy is a distinctive feature, known as a Synapomorphy, 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 (cladistics), outgroup taxa, not ...

. The autapomorphy (unique trait) is the presence of dorsoventrally tall

neural arch 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 ...

restricted to anterior half of centrum (excluding condylar ball) in anterior-most

. Other unusual characters include a spinopostzygapophyseal laminae in middle–posterior dorsal vertebrae bifurcate into medial and lateral branches, an astragalar ascending process that does not extend to the posterior margin of the astragalus and the presence of a calcaneum. Other potentially unusual features were also listed. These traits distinguish ''Elaltitan'' from all other

titanosauriform Macronaria is a clade of sauropod dinosaurs. Macronarians are named after the large diameter of the nasal opening of their skull, known as the external naris, which exceeded the size of the orbit, the skull opening where the eye is located (hence ...

s, including ''

'' and '' Argyrosaurus'', as well as other sauropods from the lower member of the Bajo Barreal Formation, such as '' Drusilasaura'' and ''

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 ...

''. Based on comparisons with the morphologically similar

of "

''" giganteus'', which was measured as in length, the complete femur of ''Elaltitan'' would be approximately the same size. This makes it one of the largest known

s ever to have existed. Mannion & Otero (2012) also pointed out that there are currently 39 Cretaceous South American titanosauriform genera considered to be valid, the majority of which (31) are from Argentina. Its weight has been estimated at in 2014, and at in 2018. However, in 2020 Molina-Perez and Larramendi gave a smaller size of 20 meters (66 ft) and 23 tonnes (25.35 short tons).

References

{{Taxonbar, from=Q966487 Lithostrotia Dinosaur genera Cenomanian dinosaurs Bajo Barreal Formation Fossil taxa described in 2012 Dinosaurs of Argentina