''Australotitan'' () is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

titanosauria 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 bo ...

that existed during the

Cenomanian The Cenomanian is, in the ICS' geological timescale, the oldest or earliest age of the Late Cretaceous Epoch or the lowest stage of the Upper Cretaceous Series. An age is a unit of geochronology; it is a unit of time; the stage is a unit in the s ...

Turonian The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous Epoch, or a stage in the Upper Cretaceous Series. It spans the time between 93.9 ± 0.8 Ma and 89.8 ± 1 Ma (million years ago). The Turonian is preceded by t ...

age of 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 ...

in what is now southern-central

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , established_ ...

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

. The genus contains a single species, ''Australotitan cooperensis''.

Discovery and naming

3D Restorations of Australotitan Holotype

''Australotitan'' was discovered in 2005 within the

Winton Formation The Winton Formation is a Cretaceous geological formation in central-western Queensland, Australia. It is late Albian to early Turonian in age. The formation blankets large areas of central-western Queensland. It consists of sedimentary rocks suc ...

of southwest

, Australia, near the town of Eromanga. Sandy Mackenzie, the discoverer, had already collected other bones on the land of his parents in 2004. The

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

material was then prepared and excavated in conjunction with the

Queensland Museum The Queensland Museum is the state museum of Queensland, dedicated to natural history, cultural heritage, science and human achievement. The museum currently operates from its headquarters and general museum in South Brisbane with specialist mu ...

and the Eromanga Natural History Museum between November 2005 and April 2010. It was nicknamed "Cooper" after its discovery being from the Cooper-Eromanga Basin, Cooper Creek system, ‘the Cooper Country”. 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 ...

, EMF102 (nicknamed "Cooper"), was described in 2021 on the basis of a partial skeleton consisting of a partial left

scapula The scapula (plural 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 eithe ...

, partial left and complete right

humeri 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 round ...

, right

ulna The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...

, the right and left pubes and

ischia Ischia ( , , ) is a volcanic island in the Tyrrhenian Sea. It lies at the northern end of the Gulf of Naples, about from Naples. It is the largest of the Phlegrean Islands. Roughly trapezoidal in shape, it measures approximately east to west ...

, and partial right and left

femora 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 t ...

. An additional three specimens were referred to the genus: EMF164, nicknamed "George," (fragmented

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 ...

, presacral

vertebra The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...

e, and

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

material), EMF105 (a complete femur), and EMF165 (a distal humerus). Several of the fossils found and worked on at Eromanga Natural History Museum are seen to have been trampled and compressed during deposition. This was the result of multiple smaller sauropods walking in a single line. The trackway has a total length of approximately . 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 ...

, ''A. cooperensis,'' was named and described by Scott A. Hocknull, Melville Wilkinson, Rochelle A. Lawrence, Vladislav Konstantinov, Stuart Mackenzie and Robyn Mackenzie in 2021. The generic name, ''Australotitan'', combines 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 ...

word "australis," meaning "southern," as it was found in Australia (which is sometimes referred to as "The Great ''Southern'' Land"), with the Greek word "Tιτάν" meaning "titan", in reference to the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

mythological

Titans In Greek mythology, the Titans ( grc, οἱ Τῑτᾶνες, ''hoi Tītânes'', , ''ho Tītân'') were the pre-Olympian gods. According to the ''Theogony'' of Hesiod, they were the twelve children of the primordial parents Uranus (Sky) and Ga ...

and the dinosaur's gigantic size. The specific name, ''cooperensis'', refers to the

Cooper Creek The Cooper Creek (formerly Cooper's Creek) is a river in the Australian states of Queensland and South Australia. It was the site of the death of the explorers Burke and Wills in 1861. It is sometimes known as the Barcoo River from one of its t ...

system near the initial location of the holotype, and the nickname given to the holotype when it was discovered. Australotitan cooperensis

Description

''Australotitan'' represents the largest known Australian dinosaur. The thighbone of specimen EMF164 has a length of , similar in size to the femora of ''

Futalognkosaurus ''Futalognkosaurus'' ( ; meaning "giant chief lizard") is a genus of titanosaurian dinosaur. The herbivorous ''Futalognkosaurus'' lived approximately 87 million years ago in the Portezuelo Formation, in what is now Argentina, of the Coniacian st ...

'' and ''

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 ...

'', though smaller than those of ''

Patagotitan ''Patagotitan'' is a genus of titanosaurian sauropod dinosaur from the Cerro Barcino Formation in Chubut Province, Patagonia, Argentina. The genus contains a single species known from multiple individuals: ''Patagotitan mayorum'', first announce ...

''. The describing authors deliberately abstained from providing a size estimate, as it is notoriously difficult to obtain reliable results for sauropods. The discovery of ''Australotitan'' indicates that the gigantic

n sauropods were present during the mid-Cretaceous of eastern

Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages ...

Classification

In a phylogenetic analysis performed by Hocknull ''et al.,'' ''Australotitan'' was recovered as a

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 th ...

. In eleven out of fourteen analyses, it was placed in a clade with the contemporaneous Titanosaur ''

Diamantinasaurus ''Diamantinasaurus'' is a genus of titanosaurian sauropod from Australia that lived during the early Late Cretaceous, about 94 million years ago. The type species of the genus is ''D. matildae'', first described and named in 2009 in paleontology, ...

'', which, depending on the dataset, also included other

Sauropods ''

Wintonotitan ''Wintonotitan'' (meaning " Winton titan") is a genus of titanosauriform dinosaur from late Albian (Early Cretaceous)-age Winton Formation of Australia. It is known from partial postcranial remains. Description and history Fossils that are ...

'' and ''

Savannasaurus ''Savannasaurus'' is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Winton Formation of Queensland, Australia. It contains one species, ''Savannasaurus elliottorum'', named in 2016 by Stephen Poropat and colleagues. The holot ...

'', and sometimes also ''

Sarmientosaurus ''Sarmientosaurus'' is a genus of titanosaurian sauropod dinosaur belonging to the Titanosauria. It lived in what is now South America, specifically Argentina, during the Upper Cretaceous Period about 95 million years ago. The type species is ' ...

'', ''

Baotianmansaurus ''Baotianmansaurus'' (named after the Baotianman National Nature Reserve) is a genus of titanosaur sauropod dinosaur. Its fossils have been found in Upper Cretaceous rocks in Henan, China, within the Gaogou Formation. The type species is ''B ...

'', ''

Dongyangosaurus ''Dongyangosaurus'' is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous. The only species is ''Dongyangosaurus sinensis'', from which only a single fragmentary skeleton is known, coming from the Zhejiang province of eastern Chin ...

'', ''

Erketu ''Erketu'' (meaning "Erketü Tengri") is a genus of somphospondylan sauropod dinosaur that lived in Asia during the Late Cretaceous roughly between 96 million and 89 million years ago. Its fossils were found in Mongolia between 2002 and 2003 du ...

'', and '' Pitekunsaurus''. This places it in the clade Diamantinasauria

sensu ''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular co ...

Poropat ''et al.'' (2021).

References

{{Taxonbar, from=Q107141748 Titanosaurs Fossils of Australia Fossil taxa described in 2021 Cretaceous dinosaurs of Australia