Tangasaurus

Tangasaurus was first described and named by Sidney H. Haughton in 1924 and the type species is Tangasaurus mennelli. The generic name is derived from the name of the Tanga Region in which the only known specimens were found, and Greek sauros, meaning "lizard". The specific name honors F. P. Mennell, the geologist who reported and collected the specimens of Tangasaurus. ==Discovery==

Tangasaurus is known only from three syntypes which represent two individuals. The small individual, which is well preserved in two specimens (part and counterpart) and is known from a partial skull and a nearly complete postcranial skeleton, was designated as the lectotype of the genus. The part slab (showing the partial skull and postcranial) is hosted at the Bulawayo Museum, Zimbabwe, while the counterpart slab SAM 6231 (showing the other side of the postcranial) is hosted at the South African Museum, Cape Town. The third syntype, SAM 6232, represents a nearly complete postcranial skeleton from a larger individual, but it is poorly preserved. All specimens were collected by F. P. Mennell in 1922 at the Mizimbazi River near Tanga City, northeastern Tanzania. During that time the Mozambique Channel had just started to open. However, a reexamination of these specimens by Carroll (1981) and Currie (1982) has shown that they represent a different genus, Thadeosaurus, known only from Madagascar. Another specimen from Madagascar, MNHN 1908-32-57, was also tentatively referred to Tangasaurus. However, Currie (1980) found it to represent a new and distinct genus which he named Acerosodontosaurus. ==Description==

Tangasaurus was described and named by Sidney H. Haughton in 1924 who found it to be a probable diapsid reptile that, because of the long, powerful, flattened tail, had become adapted for an aquatic existence. Contrary to Haughton, Piveteau (1926) considered Tangasaurus to be a primarily terrestrial animal. he considered it to be related to the Araeoscelis, Kadaliosaurus, Broomia and the "eosuchians" (a defunct clade that used to unite all diapsids more advanced than Araeoscelis) Saurosternon and Pleurosaurus. Described by Piveteau (1926), Hovasaurus boulei from Madagascar was considered to be related to Mesosaurus. Although not as specialized as Mesosaurus for living in the water, Piveteau noted its short neck, short manus, well developed haemal spines and slight pachyostosis of the ribs. Piveteau (1926) included Broomia, Saurosternon and Tangasaurus in the Tangasaurinae. The known specimens of Tangasaurus were redescribed by Philip J. Currie (1982). He diagnosed the genus on the basis of two autapomorphies: It possesses high and rectangular neural spines of the dorsal vertebrae and the height of neural spine of mid-caudal vertebra about 35% greater than length of associated centrum, and about 75% length of associated haemal arch and spine. }} More resolved results were obtained by Robert R. Reisz, Sean P. Modesto and Diane M. Scott (2011) in their description of Orovenator. However, those results required the exclusion of the fragmentary taxa Galesphyrus, Kenyasaurus, Palaeagama and Saurosternon from their analysis. The cladogram below shows Tangasaurus phylogenetic position among other neodiapsids following Reisz et al., 2011. }} ==References==