Tornieria Skull

''Tornieria'' ("for Tornier") is a genus of diplodocid sauropod dinosaur from the Late Jurassic in Lindi Region of Tanzania. It has a convoluted taxonomic history.

Discovery and naming

In 1907, German paleontologist Eberhard Fraas who was working the Tendaguru Beds in German East Africa (presently Tanzania), discovered two sauropod specimens at a single site ("Quarry A"). The two individuals, designated "Skeleton A" and "Skeleton B", each represented a different sauropod species. In 1908 he named these respectively ''Gigantosaurus africanus'' ("African giant lizard") and ''G. robustus'' ("Robust giant lizard"). A third, unrelated African species, "Gigantosaurus" ''dixeyi'', was named by Haughton in 1928, and has since been reassigned to ''Malawisaurus''.

However, the name ''Gigantosaurus'' had already been used for the European sauropod ''Gigantosaurus megalonyx'' Seeley, 1869. Fraas, not intending to place his species in the same genus as this English form, had believed that the name was available, since at the time the latter species was considered to be a junior synonym of ''Ornithopsis'' and Seeley in his opinion had not provided a sufficient description anyway. Another German paleontologist, Richard Sternfeld, renamed the Tanzanian sauropod ''Tornieria'' in 1911, making the two species ''Tornieria africana'' and ''T. robusta''. The generic name honours the German herpetologist Gustav Tornier.

A re-evaluation of ''Tornieria'' in 1922 by Werner Janensch concluded that one species, ''T. africana'', was actually an African species of the North American sauropod genus ''Barosaurus'': ''Barosaurus africanus''. The other African species, ''T. robusta'', later turned out to belong to a titanosaur. The titanosaur species for a time was called ''Tornieria'', but this was incorrect as ''T. africana'' had been the type species. It needed a generic name of its own and this was provided in 1991 when Rupert Wild renamed it ''Janenschia''.

If ''Tornieria'' were the same genus as ''Barosaurus'', then the name ''Tornieria'' would be abandoned as a junior subjective synonym. However, later researchers proposed generic distinction between the American and the African form. In the early 21st century this usage became prevalent and in 2006 Kristian Remes in a review concluded that ''Tornieria'' was indeed distinct and a valid genus.Remes, K., 2006, "Revision of the Tendaguru sauropod ''Tornieria africana'' (Fraas) and its relevance for sauropod paleobiogeography", ''Journal of Vertebrate Paleontology'' 26(3): 651–669

A complication is formed by the fact that Janensch in 1961 recognised a variety of ''B. africanus'': ''B. africanus'' var. ''gracilis'', a morph distinguished by more gracile hind limbs. In 1980, Russell ''et al.'' promoted this to a full species: ''Barosaurus gracilis'' which then would become a ''Tornieria gracilis'' under the present usage, a combination already published by George Olshevsky in 1992.G. Olshevsky, 1992, ''A revision of the parainfraclass Archosauria Cope, 1869, excluding the advanced Crocodylia''. Mesozoic Meanderings 2, pp. 1-268 However, Remes in 2006 concluded that ''B. gracilis'' had been a ''nomen nudum'', neither holotype nor diagnosis having been provided in 1980.

Specimens and description

Elements of the original "Skeleton A" were designated by Fraas as a syntype series: SMNS 12141a, 12145a, 12143, 12140, 12142, all from the postcrania. Later some other bones from the same individual were recovered. Janensch would also refer many other fossils to ''B. africanus'', in total 630 specimens representing at least 56 separate individuals. Of these 188 would be left after the bombardments during the Second World War. Remes, however, concluded that merely a second partial skeleton, "Skeleton k", including also some skull elements, could be reliably referred, and a series of caudal vertebrae. The remains are from the later strata of the Tendaguru, the ''obere Dinosauriermergel'' or "Upper Dinosaur Marl", dating from the Tithonian.

''Tornieria'' was a large sauropod, with a maximum known femur length of suggesting an animal around the same size as ''Barosaurus''; and 23 metric tons. It shared elongated neck vertebrae and a rather long forelimb with ''Barosaurus''. However, it differed from the American form by details in the anterior caudal vertebrae and from ''Barosaurus'' and ''Diplodocus'' both by its plesiomorphic hindlimb proportions with a short lower leg.

Phylogeny

After performing a cladistic analysis, Remes (2006) concluded that ''Tornieria'' was the sister taxon of a clade formed by ''Barosaurus'' and ''Diplodocus''. It would thus be a member of the Diplodocinae. The following cladogram is based on the phylogenetic analysis conducted by Whitlock in 2011, showing the relationships of ''Tornieria'' among the other genera assigned to the taxon Diplodocidae:Whitlock, J.A. (2011). "A phylogenetic analysis of Diplodocoidea (Saurischia: Sauropoda)." Zoological Journal of the Linnean Society, Article first published online: 12 Jan 2011.

References

{{Taxonbar, from1=Q1579853, from2=Q25449618

Diplodocids
Tendaguru fauna
Late Jurassic dinosaurs of Africa
Fossil taxa described in 1911
Taxa named by Richard Sternfeld