''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 n ...
of
titanosauriform 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 ...
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'', ...
. It is also the first non-avian dinosaur discovered in
Angola
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. 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
titanosauriform, 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 wa ...
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 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. 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 was absent, and the first metacarpal was not bowed.][
]
Classification
''Angolatitan'' was a basal
Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''.
Science
* Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure
* Basal (medicine), a minimal level that is nec ...
titanosauriform, 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 the ...
'' but less derived than '' Euhelopus'' and Titanosauria, 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 th ...
ian titanosauriform.
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 ...
in age, but new data suggests that it dates to the Coniacian
The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded b ...
.Tetrapod
Tetrapods (; ) are four-limb (anatomy), limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant taxon, extant and extinct amphibians, sauropsids (reptiles, including dinosaurs and therefore birds) and synapsids (p ...
s include the turtle ''Angolachelys mbaxi
''Angolachelys'' is an extinct genus of African eucryptodiran turtle which existed in Angola during the Turonian stage of the Late Cretaceous. The type species is ''Angolachelys mbaxi''. The type MGUAN-PA includes skull, jaw, and postcranial frag ...
'', the mosasaur
Mosasaurs (from Latin ''Mosa'' meaning the 'Meuse', and Ancient Greek, 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 Ma ...
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