Australodocus

Australodocus (meaning "southern beam" from the Latin australis "southern" and the Greek dokos/δοκоς "beam") is a genus of sauropod dinosaur that lived during the Late Jurassic period, around 150 million years ago, in what is now Tanzania. Though initially considered a diplodocid, recent analyses suggest it may instead be a titanosauriform.

Australodocus
Temporal range: Late Jurassic, Tithonian
Cervical vertebra
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Suborder: †Sauropodomorpha
Clade: †Sauropoda
Clade: †Titanosauriformes
Clade: †Somphospondyli
Genus: †Australodocus
Remes, 2007
Species:
†A. bohetii
Binomial name
†Australodocus bohetii
Remes, 2007

Discovery and naming
The Upper Dinosaur Member, which is the layer of the Tendaguru Formation that the holotype was recovered from

The remains of Australodocus bohetii were recovered from the Upper Dinosaur Member of the Tendaguru Formation of Tanzania, which has been a fertile ground for many Jurassic dinosaurs, including several genera of large sauropods, such as Giraffatitan, Wamweracaudia, Janenschia, Tendaguria, and Tornieria. Australodocus itself is based on two neck vertebrae, which are less elongate than those of other diplodocids and differ in other anatomical details. These vertebrae were originally part of a series of four vertebrae collected in the 1909 expedition led by Werner Janensch; like some other fossils collected by German expeditions to Africa, the other bones were destroyed in World War II. The 2007 description of the surviving bones increases the known diversity of sauropods and diplodocids in Tendaguru.[1]

The genus name is derived from the fact it was initially considered a southern (Gondwanan) relative of Diplodocus. The species name honors Boheti bin Amrani, a native crew supervisor and chief preparator who was an important contributor to the German expeditions that first excavated the Tanzanian sites.[1]

Systematics

Australodocus was originally described as a diplodocid, because it had double (bifurcate) neural spines on some of its vertebra, a characteristic normally associated with diplodocoid sauropods. However, several later studies by John Whitlock and colleagues found that Australodocus is actually a member of the sauropod clade Titanosauriformes, possibly closely related to Brachiosaurus. The presence of a higher number of macronarian sauropods in the Tendaguru environment compared to numerous diplodocoids in the Morrison Formation may be due to previously known differences in environment, with the Tendaguru being dominated by conifer forest, and the Morrison being dominated by open plains of low-browse flora.[2][3] Tschopp et al. (2015) recovered Australodocus as a diplodocine diplodocid, closely related to Supersaurus and Dinheirosaurus (which may be a synonym of the former), but stressed that the low number of titanosauriform taxa used in the cladistic analysis made such a placement untenable due to the shared somphospondylous internal structure of Australodocus and somphospondylian titanosauriforms.[4] Mannion et al.(2019) found Australodocus to be a non-titanosaur somphospondyl based on the somphospondylous nature of the internal structure of the cervicals, considering it a potential euhelopodid.[5]

Size

Gregory S. Paul in 2010 estimated its length at about 17 metres (56 ft) and weight at just 4,000 kilograms (8,800 lb).[6]

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References
  1. Remes, Kristian (2007). "A second Gondwanan diplodocid dinosaur from the Upper Jurassic Tendaguru Beds of Tanzania, East Africa". Palaeontology. 50 (3): 653–667. doi:10.1111/j.1475-4983.2007.00652.x.
  2. Whitlock, John (2011). "A phylogenetic analysis of Diplodocoidea (Saurischia: Sauropoda)". Zoological Journal of the Linnean Society. 161 (4): 872–915. doi:10.1111/j.1096-3642.2010.00665.x.
  3. Whitlock, J.A. (2011). "Re-evaluation of Australodocus bohetii, a putative diplodocoid sauropod from the Tendaguru Formation of Tanzania, with comment on Late Jurassic sauropod faunal diversity and palaeoecology". Palaeogeography, Palaeoclimatology, Palaeoecology. 309 (3–4): 333–341. Bibcode:2011PPP...309..333W. doi:10.1016/j.palaeo.2011.07.001.
  4. "A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda)". PeerJ. Retrieved 2015-12-07.
  5. Philip D Mannion, Paul Upchurch, Daniela Schwarz, Oliver Wings, 2019, "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
  6. Paul, G.S., 2010, The Princeton Field Guide to Dinosaurs, Princeton University Press p. 189 - 190.
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