''Jobaria'' is a genus of sauropod dinosaur that lived in what is now

Niger Niger, officially the Republic of the Niger, is a landlocked country in West Africa. It is a unitary state Geography of Niger#Political geography, bordered by Libya to the Libya–Niger border, north-east, Chad to the Chad–Niger border, east ...

during the middle

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

Period, between 164 and 161 million years ago. ''Jobaria'' is currently the only known valid sauropod from the Tiouraren, where it was discovered in 1997.

Discovery

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. 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. The sediments in which it was found were originally thought to represent the

Hauterivian The Hauterivian is, in the geologic timescale, an age in the Early Cretaceous Epoch or a stage in the Lower Cretaceous Series. It spans the time between 132.6 ± 2 Ma and 125.77 (million years ago). The Hauterivian is preceded by the Valangi ...

to Barremian stages of the early

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

Period, dating ''Jobaria'' to approximately 132 million years ago. However, re-interpretation of the sediments showed that they are more likely from the

Bathonian In the geologic timescale the Bathonian is an age (geology), age and stage (stratigraphy), stage of the Middle Jurassic. It lasted from approximately 168.2 ±1.2 annum, Ma to around 165.3 ±1.1 Ma (million years ago). The Bathonian Age succeeds ...

to Oxfordian stages of the middle

in age, between 167 and 161 million years ago.

Description

''Jobaria'' was a primitive sauropod, about long and estimated to weigh about . In 2016

Gregory S. Paul Gregory Scott Paul (born December 24, 1954) is an American freelance researcher, author and illustrator who works in paleontology. He is best known for his work and research on theropoda, theropod dinosaurs and his detailed illustrations, both l ...

gave a lower estimation of and . 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 Paul Callistus Sereno (born October 11, 1957) is a professor of paleontology at the University of Chicago who has discovered several new dinosaur species on several continents, including at sites in Inner Mongolia, Argentina, Morocco and Niger. ...

concluded, after comparing the ratios of

humerus The humerus (; : humeri) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius (bone), radius and ulna, and consists of three sections. The humeral upper extrem ...

and

femur The femur (; : femurs or femora ), or thigh bone is the only long bone, bone in the thigh — the region of the lower limb between the hip and the knee. In many quadrupeds, four-legged animals the femur is the upper bone of the hindleg. The Femo ...

circumferences in ''Jobaria'' to extant

elephant Elephants are the largest living land animals. Three living species are currently recognised: the African bush elephant ('' Loxodonta africana''), the African forest elephant (''L. cyclotis''), and the Asian elephant ('' Elephas maximus ...

s. 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

The phylogenetic relationships of ''Jobaria'' are uncertain; it has been interpreted either as a basal

macronaria Macronaria is a clade of sauropod dinosaurs. Macronarians are named after the large diameter of the nasal opening of their skull, known as the external naris, which exceeded the size of the orbit, the skull opening where the eye is located (hence ...

n, or as a non- neosauropod eusauropod, basal to the neosauropod

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

. The following cladogram shows the position of ''Jobaria'' within the Eusauropoda.

References

External links

''Jobaria'' in the Dino Directory
{{Taxonbar, from=Q131398 Sauropoda Dinosaur genera Middle Jurassic dinosaurs Fossil taxa described in 1999 Taxa named by Paul Sereno Dinosaurs of Niger