Jobaria

*Jobaria tiguidensis*

* Jurassic Park Institute Artwork
* Robert F Walters Artwork

***Jobaria*** was a sauropod dinosaur discovered in the Sahara Desert in 1997, and is one of the most completely known Jurassic sauropods. It was named after "Jobar", a creature of local legends, and is thought to have been about 18 meters long. It lived during the Early Cretaceous (Aptian or Albian age).

Unusually for its late occurrence, *Jobaria* seems to be a very primitive sauropod. It has been interpreted either as a basal macronarian (Upchurch *et al.*, 2004), or as a non-neosauropod eusauropod, basal to the neosauropod clade.

The backbone and tail of *Jobaria* are simple compared to the complex vertebrae and whiplast tail of the older North America sauropods *Diplodocus* and *Apatosaurus*. Unlike other Cretaceous sauropods, *Jobaria* had spoon-shaped teeth.

## Description

Jobaria was a primitive sauropod, about 18.2 metres (60 ft) long and estimated to weigh about 22.4 tonnes (24.7 short tons). In 2016 Gregory S. Paul gave a lower estimation of 16 metres (52 ft) and 16 tonnes (18 short tons). 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. 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.
The head of Jobaria slightly resembles to Camarasaurus but elongated.

## 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 to Barremian stages of the early Cretaceous Period, dating Jobaria to approximately 132 million years ago. 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.

## Classification

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

## Posture

Paul Sereno concluded, after comparing the ratios of humerus and femur circumferences in *Jobaria* to extant elephants, that *Jobaria* may have been able to rear up on its hind legs. As the weight distribution of *Jobaria* indicates that it was supported by the rear limbs rather than the forelimbs (as in elephants), it has been speculation that as elephants can rear-up, then *Jobaria* would have been able to more easily.

## JPInstitute.com Description

Jobaria is one of the many exciting new discoveries made in Africa. It was a giant four-legged plant-eater that had a relatively short, flexible tail and neck. It also had a mouthful of spoon-like teeth, and large eye and nose openings.

Jobaria's skeleton was so flexible, that it may have been able to rear up on its hind legs for feeding or defense. This was a common feature found on early, more primitive sauropods, but Jobaria lived in the Cretaceous, and was one of the last sauropods. This has led to speculation that Jobaria survived a long, long time as a species, maybe 50 million years, without much evolutionary change.

It seems that Jobaria, with keen senses, great size, and a flexible tail and neck, was the perfect Sauropod. If so, it may have outlasted all others of its kind. The first Jobaria located was 95% preserved, highly unusual for a sauropod.

## Dinosaur Field Guide Description

Jobaria (after a creature from Tuareg mythology) is a unique sauropod, or large long-necked dinosaur. It has thick, heavy legs and a very wide stance. Its teeth are thick and heavy, too. Jobaria's neck is short, and so is the tail. This is a very powerful dinosaur. It fed mostly on the leaves of trees, so it had to be big enough to reach them, and big enough to support its own weight. Jobaria also had to fight off Afrovenator (the "Allosaurus" of this time) with its thumb claw! jobaria was found in 1 997 but not named until 1999. Skeletons of several other specimens of Jobaria were unearthed at the same time, so it took years for the material to be prepared. Without the help of laboratory technicians who prepare the bones, scientists would need decades to describe and prepare new finds by themselves. Imagine finding a dinosaur in the field. It has over 200 bones, many up to 6 feet (1.8 m) long and weighing several hundred pounds. You are working in a desert. The daily temperature is over 100 degrees, and the wind blasts sand in your face, clothes, and food. The nearest English-speaking country is over 1,000 miles (1,600 km) away! That's what Paul Sereno and his University of Chicago crew had to deal with while digging in the Sahara Desert for Jobaria.

### Fun Facts

Jobaria has its own Web page at www.jobaria.org.

### Trivia

Casts of Jobaria are on display in Chicago.

## Links

http://web.archive.org/web/20040806051510fw\_/http://www.jpinstitute.com/dinopedia/dinocards/dc\_jobar.html#