Janenschia has had a convoluted nomenclatural history. In 1907,
Eberhard Fraas at "site P", nine hundred metres to the southeast of Tendaguru Hill, discovered two skeletons of gigantic sauropods. They were designated as "Skeleton A" and "Skeleton B". The fossils were transported to the collection of the
Stuttgarter Naturaliensammlung in
Stuttgart,
Germany. Fraas in 1908 decided to name both skeletons as different species of one genus:
Gigantosaurus. Skeleton A became
Gigantosaurus africanus and skeleton B became
Gigantosaurus robustus. The latter species was based on the
holotype partial skeleton
SMNS 12144, consisting of a right hindlimb. The
specific name was inspired by the heavy build of the animal. While doing so, Fraas knew full well that the name
Gigantosaurus was already preoccupied by another taxon:
Gigantosaurus megalonyx, named by
Harry Govier Seeley in 1869. Fraas thought his actions could be justified by the fact that the description by Seeley had been limited and that the material of
G. megalonyx had since been referred to another genus,
Ornithopsis, by
Richard Lydekker. In 1911,
Richard Sternfeld renamed
Gigantosaurus Fraas 1908 to
Tornieria, pointing out that Fraas's arguments had been irrelevant.
Tornieria africana became the type species of the new genus.
G. robustus was placed in
Tornieria, as
T. robusta. Sternfeld's move was not well received in Germany, as he had acted without consent of the ailing Fraas. In a 1922 article describing the hand of the animal,
Werner Janensch, who at the Tendaguru had collected additional material, announced that he would keep using the name
Gigantosaurus robustus. He claimed that
G. megalonyx was a forgotten
nomen oblitum and that the rules of the zoological nomenclature should be disregarded if they caused instability by replacing a well-known name by a completely new one. At the same time he synonymized
Tornieria with
Barosaurus as regarded its type species which then became a
Barosaurus africanus. Janensch, for the remainder of his career, would consistently apply the name
Gigantosaurus robustus. In 1928,
Sidney Henry Haughton exceptionally assigned
Tornieria robusta to
Barosaurus also, as a
Barosaurus robustus. In 1930, Baron
Franz Nopcsa rejected Janensch's arguments. He admitted that Sternfeld had been discourteous but pointed out that the ICZN only in 1927 recommended that the original author should be involved in such name changes. It would thus be absurd to object to an article written in 1911 — and in any case the lack of courtesy had no bearing on the validity of the name. Nopcsa had found several later mentions of
G. megalonyx, which thus had not been a
nomen oblitum. Furthermore,
Gigantosaurus robustus had not exactly been a well-known name itself, prior to 1922. Distasteful as it might be, Nopcsa concluded, it was inevitable to consider
Tornieria to be a valid name. SMNS 12144 was subsequently referred to
Tornieria by other authors. In 1991, German palaeontologist
Rupert Wild of the
Stuttgart Museum of Natural Sciences clarified the taxonomic status of
G. robustus by concluding that it was generically distinct from
Tornieria. He renamed it
Janenschia in honor of Werner Janensch, who had studied the vertebrate fauna from Tendaguru.
Janenschia was placed in the family
Titanosauridae, making it the oldest member of
Titanosauria. A number of specimens formerly assigned to
Janenschia have been recognized as distinct genera. Two anterior dorsal vertebrae, and a possible posterior cervical vertebra, previously referred to the genus, were named
Tendaguria in 2000. On the other hand, the caudal vertebral series
MB.R.2091.1–30 does not overlap with SMNS 12144 and instead represents the first taxon of
Mamenchisauridae from outside Asia,
Wamweracaudia.{{cite journal |doi=10.1111/zoj.12029 |title=Osteology of the Late Jurassic Portuguese sauropod dinosaur
Lusotitan atalaiensis (Macronaria) and the evolutionary history of basal titanosauriforms |journal=Zoological Journal of the Linnean Society |volume=168 |pages=98–206 |year=2013 |last1=Mannion |first1=Philip D. |last2=Upchurch |first2=Paul |last3=Barnes |first3=Rosie N. |last4=Mateus |first4=Octávio ==See also==