Janenschia

Janenschia (named after Werner Janensch) is a large herbivorous sauropod dinosaur from the Late Jurassic Tendaguru Formation of Tanzania, Africa, 155 million years ago.

Alternate view

Janenschia
Temporal range: 155–145 Ma Late Jurassic
Janenschia humerus, radius and ulna at the Museum für Naturkunde, Berlin
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Suborder: †Sauropodomorpha
Clade: †Sauropoda
Clade: †Neosauropoda
Clade: †Macronaria
Genus: †Janenschia
Wild, 1991
Species:
†J. robusta
Binomial name
†Janenschia robusta
(Fraas, 1908)

Discovery and naming

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.[1] 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.[2][3][4][5][6]

In 1911, Richard Sternfeld renamed Gigantosaurus Fraas 1908 into Tornieria, pointing out that Fraas's arguments had been irrelevant. Torniera africana became the type species of the new genus.[7] 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 1922, Werner Janensch, who at the Tendaguru had collected additional material, in an article describing the hand of the animal 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.[8] 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.[9]

In 1930, Baron Franz Nopcsa rejected Janensch' 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 prior to 1922 not exactly been a well-known name itself. Distasteful as it might be, Nopcsa concluded, it was inevitable to consider Tornieria to be a valid name.[10] SMNS 12144 was subsequently referred to Tornieria by other authors.[11][12][13][14]

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.[15]

A number of specimens formerly assigned to Janenschia have been recognized as distinct genera. Two anterior dorsal vertebrae, and a possibly posterior cervical vertebra, previously referred to the genus, were named Tendaguria in 2000.[16] 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.[17][18] Recent cladistic analysis places Janenschia as a non-titanosauriform sauropod.[19][18]

Paleobiology

As a sauropod, it would have been a quadrupedal herbivore.[20]

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References
  1. Fraas, E. (1908) "Dinosaurierfunde in Ostafrika", Jahreshefte des Vereins für Vaterländische Naturkunde in Württemberg 64: 84–86
  2. E. Fraas. 1908. "Ostafrikanische Dinosaurier". Mitteilungen aus dem Königlichen Naturalien-Kabinett zu Stuttgart 55(61): 105-144
  3. E. Fraas. 1908. "Dinosaurier in Deutsch-Ostafrika". Die Umschau 12(48): 943-948
  4. E. Fraas. 1911. "Die ostafrikanischen Dinosaurier". Verhandlungen der Gesellschaft Deutscher Naturfoscher und Ärzte 83(1): 27-41
  5. E. Fraas. 1912. "Die ostafrikanischen Dinosaurier". Sammlung Wissenschaftlicher Vorträge 1: 3-21
  6. Lydekker, R. 1888. Catalogue of the Fossil Reptilia and Amphibia in the British Museum (Natural History). Part I. Containing the Orders Ornithosauria, Crocodilia, Dinosauria, Squamata, Rhynchocephalia, and Proterosauria. British Museum (Natural History), London, 309 pp
  7. R. Sternfeld. 1911. "Zur Nomenklatur der Gattung Gigantosaurus Fraas [On the nomenclature of the genus Gigantosaurus Fraas]". Sitzungsberichte der Gesellschaft Naturforschender Freunde zu Berlin 8: 398
  8. Janensch, W., 1922, "Das Handskelett von Gigantosaurus robustus und Brachiosaurus brancai aus den Tendaguru-Schichten Deutsch-Ostafrikas", Centralblatt für Mineralogie, Geologie und Paläontologie 1922: 464–480
  9. Haughton, S. H. (1928). "On some reptilian remains from the Dinosaur Beds of Nyasaland". Transactions of the Royal Society of South Africa. 16: 67. doi:10.1080/00359192809519658.
  10. Nopcsa, F. 1930. "Zur Systematik und Biologie der Sauropoden". Palaeobiologica, 3: 40-52
  11. Stromer, E. (1932). "Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wüsten Ägyptens. II. Wirbeltierreste der Baharîje-Stufe (unterstes Cenoman). 11. Sauropoda" [Results of the expeditions of Professor E. Stromer in the Egyptian deserts. II. Vertebrate animal remains from the Baharîje bed (lowest Cenomanian). 11. Sauropoda]. Abhandlungen der Bayerischen Akademie der Wissenschaften Mathematisch-naturwissenschaftliche Abteilung, Neue Folge 10:1–21
  12. Steel, R. (1970). Part 14. Saurischia. Handbuch der Paläoherpetologie/Encyclopedia of Paleoherpetology. Gustav Fischer Verlag, Stuttgart pp. 1–87
  13. Jain, S. L.; Kutty, T. S.; Roy-Chowdhury, T. K. and Chatterjee, S. (1979). "Some characteristics of Barapasaurus tagorei, a sauropod dinosaur from the Lower Jurassic of Deccan, India". In B. Laskar & C. S. Raja Rao (eds.), Fourth International Gondwana Symposium: Papers. Hindustan Publishing Corporation, Delhi 1:204–216
  14. Buffetaut, E. (1989). Une vertèbre de Dinosaure Titanosauridé dans le Cénomanien du Mans et ses implications paléobiogéographiques [A titanosaurid dinosaur vertebra in the Cenomanian of Le Mans and its paleobiogeographic implications]. Comptes Rendus de l'Académie des Sciences à Paris, Série II 309:437–443
  15. Wild, R. (1991). Janenschia n. g. robusta (E. Fraas 1908) pro Tornieria robusta (E. Fraas 1908) (Reptilia, Saurischia, Sauropodomorpha) [Janenschia n. g. robusta (E. Fraas 1908) for Tornieria robusta (E. Fraas 1908) (Reptilia, Saurischia, Sauropodomorpha)]. Stuttgarter Beiträge zur Naturkunde, Serie B (Geologie und Paläontologie) 173:1–4
  16. Bonaparte, J.F.; Heinrich, W.-D.; Wild, R. (2000). "Review of Janenschia Wild, with the description of a new sauropod from the Tendaguru beds of Tanzania and a discussion on the systematic value of procoelous caudal vertebrae in the Sauropoda". Palaeontographica Abteilung A. 256 (1–3): 25–76.
  17. Mannion, Philip D.; Upchurch, Paul; Barnes, Rosie N.; Mateus, Octávio (2013). "Osteology of the Late Jurassic Portuguese sauropod dinosaur Lusotitan atalaiensis (Macronaria) and the evolutionary history of basal titanosauriforms" (PDF). Zoological Journal of the Linnean Society. 168: 98–206. doi:10.1111/zoj.12029.
  18. Philip D Mannion, Paul Upchurch, Daniela Schwarz, Oliver Wings; Taxonomic affinities of the putative titanosaurs from the Late Jurassic Tendaguru Formation of Tanzania: phylogenetic and biogeographic implications for eusauropod dinosaur evolution, Zoological Journal of the Linnean Society, , zly068, https://doi.org/10.1093/zoolinnean/zly068
  19. Upchurch P.; Mannion P.D.; Taylor M.P. (2015). "The Anatomy and Phylogenetic Relationships of "Pelorosaurus" becklesii (Neosauropoda, Macronaria) from the Early Cretaceous of England". PLoS ONE. 10 (6): e0125819. doi:10.1371/journal.pone.0125819. PMC 4454574. PMID 26039587.
  20. Upchurch, P.M., Barrett, P.M., and Dodson, P. (2004). "Sauropoda", pp. 259–322 in Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.). The Dinosauria (2nd edition). University of California Press:Berkeley. ISBN 0-520-24209-2
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