Angolatitan

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Angolatitan
Temporal range: Late Turonian, 90 Ma
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Sauropodomorpha
Clade: Sauropoda
Clade: Titanosauriformes
Genus: Angolatitan
Mateus et al., 2011
Type species
Angolatitan adamastor
Mateus et al., 2011

Angolatitan ("Angolan giant") is a genus of sauropod dinosaur from the Upper Cretaceous and the first dinosaur discovered in Angola. Based on a forelimb, it was described in 2011 by Octávio Mateus and colleagues. The only species is Angolatitan adamastor. Angolatitan was a relict form of its time, being a basal titanosauriform sauropod in the Late Cretaceous, when more derived titanosaurs were far more common.[1]

Discovery and naming[edit]

During the Angolan Civil War, palaeontological field research was not possible in Angola.[2] After the civil war 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.[1]

Angolatitan adamastor was described by Octávio Mateus and colleagues in 2011. The generic name means "Angolan giant". Adamastor is a mythological sea monster that represented the dangers Portuguese sailors faced in the southern Atlantic.[1] Until 1975, Angola was a Portuguese colony.[2]

Description[edit]

The only specimen is a partial right forelimb, including shoulder blade, upper arm bone, the two bones of the lower arm (ulna and radius), and three metacarpals. These fossils (Field number MGUAN-PA-003) are stored in the Museu de Geologia of the Universidade Agostinho Neto in Luanda.[1]

The upper arm bone measures 110 centimetres (43 in), the ulna 69 centimetres (27 in) 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.[1]

Classification[edit]

Angolatitan was a basal titanosauriform, more derived than Brachiosaurus 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 O'Conner (2017) recover Angolatitan as a non-titanosaurian titanosauriform.[3]

Palaeoecology[edit]

The specimen was found in a 50 m thick subsection of the Itombe Formation, called the Tadi Beds, which could be dated late Turonian in age (approximately 90 million years old) based on the characteristic fish community. These rocks were deposited under marginary marine conditions; fossils include ammonites, echinoderms, and fishes (including sharks). Tetrapods include the turtle Angolachelys mbaxi, the Mosasaurs Angolasaurus bocagei and Tylosaurus iembeensis as well as several plesiosaur fossils.[1]

Angolatitans habitat would have been desert-like. Presumably, this sauropod would have been well adapted to very dry conditions as it is the case with today's desert elephants.[1]

References[edit]

  1. ^ a b c d e f g Mateus, O.; Jacobs, L.L.; Schulp, A.S.; Polcyn, M.J.; Tavares, T.S.; Neto, A.B.; Morais, M.L.; Antunes, M.T. (2011). "Angolatitan adamastor, a new sauropod dinosaur and the first record from Angola" (PDF). Anais da Academia Brasileira de Ciências. 83 (1): 221–233. doi:10.1590/S0001-37652011000100012. ISSN 0001-3765. 
  2. ^ a b Cooper, Rob (2011-03-17). "The gentle giant: Scientists discover plant-eating dinosaur that made even the T-Rex look small". Daily Mail. Retrieved 2011-03-20. 
  3. ^ Gorscak, E.; O'Connor, P. M.; Roberts, E. M.; Stevens, N. J. (2017). "The second titanosaurian (Dinosauria: Sauropoda) from the middle Cretaceous Galula Formation, southwestern Tanzania, with remarks on African titanosaurian diversity" (PDF). Journal of Vertebrate Paleontology. 361: 35–55. doi:10.1080/02724634.2017.1343250.