''Angolatitan'' (meaning "Angolan giant") is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

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 ...

sauropod dinosaur from the

Upper 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'', th ...

. It is also the first non-avian dinosaur discovered in

Angola , national_anthem = " Angola Avante"() , image_map = , map_caption = , capital = Luanda , religion = , religion_year = 2020 , religion_ref = , coordina ...

. The genus contains a single species, ''Angolatitan adamastor'', known from a partial right forelimb. ''Angolatitan'' was a relict form of its time; it was a Late Cretaceous basal

, when more derived titanosaurs were far more common.

Discovery and naming

After the

Angolan Civil War The Angolan Civil War ( pt, Guerra Civil Angolana) was a civil war in Angola, beginning in 1975 and continuing, with interludes, until 2002. The war immediately began after Angola became independent from Portugal in November 1975. The war was ...

ended in 2002, the PaleoAngola project planned the first Angolan palaeontological expeditions since the 1960s. The first of these expeditions started in 2005 to explore Angola's fossil rich upper Cretaceous rocks, leading to the discovery of ''Angolatitan''. The discovery was made by

Octávio Mateus Octávio Mateus (born 1975) is a Portuguese dinosaur paleontologist and biologist Professor of Paleontology at the Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa. He graduated in Universidade de Évora and received his PhD at U ...

on May the 25 near Iembe in the province of Bengo, and excavations were conducted during May and August 2006. ''Angolatitan'' was described by Octávio Mateus and colleagues in 2011. The generic name means "Angolan giant". The specific name is derived from Adamastor, a mythological sea monster that represented the dangers Portuguese sailors faced in the southern Atlantic. Until 1975, Angola was a Portuguese colony.

Description

The only specimen is a partial right forelimb, including shoulder blade, upper arm bone, the two bones of the lower arm (

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 ...

and

radius In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...

), and three

metacarpals In human anatomy, the metacarpal bones or metacarpus form the intermediate part of the skeletal hand located between the phalanges of the fingers and the carpal bones of the wrist, which forms the connection to the forearm. The metacarpal bones ar ...

. These fossils (Field number MGUAN-PA-003) are stored in the ''Museu de Geologia'' of the ''Universidade Agostinho Neto'' in

Luanda Luanda () is the Capital (political), capital and largest city in Angola. It is Angola's primary port, and its major Angola#Economy, industrial, Angola#Culture, cultural and Angola#Demographics, urban centre. Located on Angola's northern Atl ...

. The upper arm bone measures , the ulna in length. In general, the forelimb was less robust than in most of the more derived titanosaurs. The metacarpals were slender and equal in length; those of titanosaurs were more robust with varying lengths. Unlike titanosaurs, the

olecranon The olecranon (, ), is a large, thick, curved bony eminence of the ulna, a long bone in the forearm that projects behind the elbow. It forms the most pointed portion of the elbow and is opposite to the cubital fossa or elbow pit. The olecranon ...

was absent, and the first metacarpal was not bowed.

Classification

''Angolatitan'' was a basal

, more derived than ''

Brachiosaurus ''Brachiosaurus'' () is a genus of sauropod dinosaur that lived in North America during the Late Jurassic, about 154to 150million years ago. It was first described by American paleontologist Elmer S. Riggs in 1903 from fossils found in th ...

'' but less derived than ''

Euhelopus ''Euhelopus'' is a genus of sauropod dinosaur that lived between 145 and 133 million years ago during the Berriasian and Valanginian stages of the Early Cretaceous in what is now Shandong Province in China. It was a large quadrupedal herbivore. U ...

'' and

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 ...

, which is notable given its relatively late appearance in the sauropod fossil record. Recent phylogenetic tests run by Gorsack and Connor (2017) recover ''Angolatitan'' as a non-

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 ...

ian

Palaeoecology

The specimen was found in a 50 m thick subsection of the Itombe Formation called the Tadi Beds. The Itombe Formation was considered

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 b ...

in age, but new data suggests that it dates to the Coniacian. These rocks were deposited under marginary marine conditions; fossils include ammonites, echinoderms, and fishes (including sharks).

Tetrapod Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids ( reptiles, including dinosaurs and therefore birds) and synapsids ( pelycosaurs, extinct t ...

s include the turtle '' Angolachelys mbaxi'', the

mosasaur Mosasaurs (from Latin ''Mosa'' meaning the 'Meuse', and Greek ' meaning 'lizard') comprise a group of extinct, large marine reptiles from the Late Cretaceous. Their first fossil remains were discovered in a limestone quarry at Maastricht on ...

s '' Angolasaurus bocagei'' and '' Tylosaurus iembeensis,'' and several plesiosaur fossils. The ecosystem inhabited by ''Angolatitan'' would have been desert-like. Presumably, this sauropod would have been well adapted to very dry conditions, similar to extant desert elephants.

References

{{Taxonbar, from=Q1287938 Macronarians Coniacian life Late Cretaceous dinosaurs of Africa Fossil taxa described in 2011