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Jobaria

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Jobaria
Temporal range: Middle Jurassic, 167–161 Ma
Skeletons of Jobaria and Suchomimus, two dinosaurs from Niger which did not coexist
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Sauropodomorpha
Clade: Sauropoda
Clade: Eusauropoda
Genus: Jobaria
Sereno et al., 1999
Type species
Jobaria tiguidensis
Sereno et al., 1999

Jobaria is a genus of sauropod dinosaur that lived in what is now Niger during the middle Jurassic Period, between 164–161 million years ago.[1]

Description

Jobaria tiguidensis restoration
Jobaria tiguidensis restoration

Jobaria was a primitive sauropod, about 18.2 metres (60 ft) long and estimated to weigh about 22.4 tonnes (24.7 short tons).[2] Its backbone and tail were simple compared to the complex vertebrae and whiplash tail of the later North America sauropods Diplodocus and Apatosaurus.

It may also have been able to rear up on its hind legs as Paul Sereno concluded, after comparing the ratios of humerus and femur circumferences in Jobaria to extant elephants.[3] The weight distribution of Jobaria indicates that it was supported by the rear limbs rather than the forelimbs (as in elephants) and is speculated that as elephants can rear up, then Jobaria would have been able to more easily.

Discovery

Cast mounted in rearing pose
Cast mounted in rearing pose

Discovered in the fall of 1997, during a four-month expedition to the Sahara desert led by paleontologist Dr. Paul Sereno, it was found in a mass-death site in the Tiourarén Formation of Niger. With over 95% of its skeleton preserved it is among the most complete sauropods ever found.[4]

The genus is named after a local mythical giant beast, Jobar, whose bones some Tuaregs believed the fossils to be. The specific name tiguidensis comes from the cliff of Tiguidi, the site of discovery.[1]

The sediments in which it was found were originally thought to represent the Hauterivian to Barremian stages of the early Cretaceous Period, dating Jobaria to approximately 132 million years ago.[1] However, re-interpretation of the sediments showed that they are more likely from the Bathonian to Oxfordian stages of the middle Jurassic in age, between 167 and 161 million years ago.[5]

Classification

The phylogenetic relationships of Jobaria are uncertain; it has been interpreted either as a basal macronarian,[6] or as a non-neosauropod eusauropod, basal to the neosauropod clade.[7]

References

  1. ^ a b c Sereno, P.; et al. (November 1999). "Cretaceous Sauropods from the Sahara and the Uneven Rate of Skeletal Evolution Among Dinosaurs". Science. 286 (5443): 1342–1347. doi:10.1126/science.286.5443.1342. PMID 10558986.
  2. ^ Henderson, Donald (2013). "Sauropod Necks: Are They Really for Heat Loss?". PLoS ONE. 8 (10): e77108. doi:10.1371/journal.pone.0077108. PMC 3812985. PMID 24204747.
  3. ^ Could Sauropods Rear?
  4. ^ Sereno, Paul. "Discoveries: Jobaria tiguidensis". Archived from the original on 8 October 2012. Retrieved 25 September 2012.
  5. ^ Rauhut; Lopez-Arbarello (2009). "Considerations on the age of the Tiouaren Formation (Iullemmeden Basin, Niger, Africa): Implications for Gondwanan Mesozoic terrestrial vertebrate faunas". Palaeogeography, Palaeoclimatology, Palaeoecology. 271: 259–267. doi:10.1016/j.palaeo.2008.10.019.
  6. ^ Upchurch, P.; Barrett, P. M.; Dodson, P. (2004). "Sauropoda". The Dinosauria (2nd ed.). University of California Press.
  7. ^ Mannion, P.D.; Allain, R.; Moine, O. (2017). "The earliest known titanosauriform sauropod dinosaur and the evolution of Brachiosauridae". PeerJ. 5: e3217. doi:10.7717/peerj.3217. PMC 5417094.
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Jobaria
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