Jobaria

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Jobaria
Temporal range: Middle Jurassic, 162Ma
Jobaria head.jpg
Skull cast at the Montshire Museum of Science
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Superorder: Dinosauria
Order: Saurischia
Suborder: Sauropodomorpha
Infraorder: Sauropoda
(unranked): Eusauropoda
Genus: Jobaria
Species: J. tiguidensis
Binomial name
Jobaria tiguidensis
Sereno et al., 1999[1]

Jobaria was a genus of sauropod dinosaur that lived in the current-day Niger during the middle Jurassic Period, between 164–161 million years ago.

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

Discovery[edit]

Discovered in the fall of 1997, during a four-month expedition to the Sahara desert lead 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.[2]

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 135 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 164 and 161 million years ago.[3]

Description[edit]

Jobaria tiguidensis restoration

Jobaria was a primitive sauropod, around 21.3 metres (70 ft) long and estimated to weight about 22.4 tonnes (25 short tons).[4] 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 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.[5] 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.

Classification[edit]

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.

References[edit]

  1. ^ a b c Sereno et al., P. (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. 
  2. ^ Sereno, Paul. "Discoveries: Jobaria tiguidensis". Retrieved 25 September 2012. 
  3. ^ Rauhut and 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.
  4. ^ Henderson, Donald M. (2006). "Burly Gaits: Centers of mass, stability, and the trackways of sauropod dinosaurs". Journal of Vertebrae Paleontology 26 (4): 907–921. doi:10.1671/0272-4634(2006)26[907:BGCOMS]2.0.CO;2. 
  5. ^ Could Sauropods Rear?
  6. ^ Upchurch, P.; Barrett, P. M. & Dodson, P. (2004). "Sauropoda". The Dinosauria (2nd edition ed.). University of California Press. 

External links[edit]