Jobaria

Last updated

Jobaria
Temporal range: Middle Jurassic, 167–161  Ma
Jobaria in the Australian Museum.jpg
Cast mounted in rearing pose. Australian Museum
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: 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 and 161 million years ago. [1] Jobaria is currently the only known valid sauropod from the Tiouraren, where it was discovered in 1997.

Contents

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. [2]

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. [3]

Description

Life restoration Jobaria tiguidensis steveoc.jpg
Life 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). [4] In 2016 Gregory S. Paul gave a lower estimation of 16 metres (52 ft) and 16 tonnes (18 short tons). [5] 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. [6] 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

Head cast, Montshire Museum of Science Jobaria head.jpg
Head cast, Montshire Museum of Science

The phylogenetic relationships of Jobaria are uncertain; it has been interpreted either as a basal macronarian, [7] or as a non-neosauropod eusauropod, basal to the neosauropod clade. [8]

The following cladogram shows the position of Jobaria within the Eusauropoda. [9]

Eusauropoda

Related Research Articles

<span class="mw-page-title-main">Sauropoda</span> Extinct clade of saurischian dinosaurs

Sauropoda, whose members are known as sauropods, is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads, and four thick, pillar-like legs. They are notable for the enormous sizes attained by some species, and the group includes the largest animals to have ever lived on land. Well-known genera include Apatosaurus, Argentinosaurus, Alamosaurus, Brachiosaurus, Camarasaurus, Diplodocus, and Mamenchisaurus.

<span class="mw-page-title-main">Sauropodomorpha</span> Extinct clade of dinosaurs

Sauropodomorpha is an extinct clade of long-necked, herbivorous, saurischian dinosaurs that includes the sauropods and their ancestral relatives. Sauropods generally grew to very large sizes, had long necks and tails, were quadrupedal, and became the largest animals to ever walk the Earth. The prosauropods, which preceded the sauropods, were smaller and were often able to walk on two legs. The sauropodomorphs were the dominant terrestrial herbivores throughout much of the Mesozoic Era, from their origins in the Late Triassic until their decline and extinction at the end of the Cretaceous.

<i>Suchomimus</i> Extinct genus of dinosaurs

Suchomimus is a genus of spinosaur dinosaur that lived between 125 and 112 million years ago in what is now Niger, North Africa, during the Aptian to early Albian stages of the Early Cretaceous Period. It was named and described by paleontologist Paul Sereno and colleagues in 1998, based on a partial skeleton from the Elrhaz Formation. Suchomimus's long and shallow skull, similar to that of a crocodile, earns it its generic name, while the specific name Suchomimus tenerensis alludes to the locality of its first remains, the Ténéré Desert.

<span class="mw-page-title-main">Brachiosauridae</span> Extinct family of dinosaurs

The Brachiosauridae are a family or clade of herbivorous, quadrupedal sauropod dinosaurs. Brachiosaurids had long necks that enabled them to access the leaves of tall trees that other sauropods would have been unable to reach. In addition, they possessed thick spoon-shaped teeth which helped them to consume tough plants more efficiently than other sauropods. They have also been characterized by a few unique traits or synapomorphies; dorsal vertebrae with 'rod-like' transverse processes and an ischium with an abbreviated pubic peduncle.

<i>Antarctosaurus</i> Sauropod dinosaur genus from Late Cretaceous

Antarctosaurus is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now South America. The type species, Antarctosaurus wichmannianus, and a second species, Antarctosaurus giganteus, were described by prolific German paleontologist Friedrich von Huene in 1929. Three additional species of Antarctosaurus have been named since then but later studies have considered them dubious or unlikely to pertain to the genus.

<i>Afrovenator</i> Extinct genus of dinosaurs

Afrovenator is a genus of megalosaurid theropod dinosaur from the Middle or Late Jurassic Period on the Tiourarén Formation and maybe the Irhazer II Formation of the Niger Sahara region in northern Africa. Afrovenator represents the only properly identified Gondwanan megalosaur, with proposed material of the group present in the Late Jurassic on Tacuarembó Formation of Uruguay and the Tendaguru Formation of Tanzania.

<span class="mw-page-title-main">Macronaria</span> Extinct clade of dinosaurs

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. Fossil evidence suggests that macronarian dinosaurs lived from the Middle Jurassic (Bathonian) through the Late Cretaceous (Maastrichtian). Macronarians have been found globally, including discoveries in Argentina, the United States, Portugal, China, and Tanzania. Like other sauropods, they are known to have inhabited primarily terrestrial areas, and little evidence exists to suggest that they spent much time in coastal environments. Macronarians are diagnosed through their distinct characters on their skulls, as well as appendicular and vertebral characters. Macronaria is composed of several subclades and families notably including Camarasauridae and Titanosauriformes, among several others. Titanosauriforms are particularly well known for being some of the largest terrestrial animals to ever exist.

<i>Haplocanthosaurus</i> Extinct genus of dinosaurs

Haplocanthosaurus is a genus of intermediate sauropod dinosaur. Two species, H. delfsi and H. priscus, are known from incomplete fossil skeletons. It lived during the late Jurassic period, 155 to 152 million years ago. The type species is H. priscus, and the referred species H. delfsi was discovered by a young college student named Edwin Delfs in Colorado, United States. Haplocanthosaurus specimens have been found in the very lowest layer of the Morrison Formation, along with Hesperosaurus mjosi, Brontosaurus yahnahpin, and Allosaurus jimmadseni.

Jeffrey A. Wilson, also known as JAW, is a paleontologist and professor of geological sciences and assistant curator at the Museum of Paleontology at the University of Michigan.

<span class="mw-page-title-main">Dicraeosauridae</span> Extinct family of dinosaurs

Dicraeosauridae is a family of diplodocoid sauropods who are the sister group to Diplodocidae. Dicraeosaurids are a part of the Flagellicaudata, along with Diplodocidae. Dicraeosauridae includes genera such as Amargasaurus, Suuwassea, Dicraeosaurus, and Brachytrachelopan. Specimens of this family have been found in North America, Asia, Africa, and South America. In 2023, a dicraeosaurid fossil was discovered in India for the first time. Their temporal range is from the Early or Middle Jurassic to the Early Cretaceous. Few dicraeosaurids survived into the Cretaceous, the youngest of which was Amargasaurus.

<i>Cristatusaurus</i> Extinct genus of dinosaurs

Cristatusaurus is a genus of theropod dinosaur that lived during the Early Cretaceous Period of what is now Niger, 112 million years ago. It was a baryonychine member of the Spinosauridae, a group of large bipedal carnivores with well-built forelimbs and elongated, crocodile-like skulls. The type species Cristatusaurus lapparenti was named in 1998 by scientists Philippe Taquet and Dale Russell, on the basis of jaw bones and some vertebrae. Two claw fossils were also later assigned to Cristatusaurus. The animal's generic name, which means "crested reptile", alludes to a sagittal crest on top of its snout; while the specific name is in honor of the French paleontologist Albert-Félix de Lapparent. Cristatusaurus is known from the Albian to Aptian Elrhaz Formation, where it would have coexisted with sauropod and iguanodontian dinosaurs, other theropods, and various crocodylomorphs.

<i>Spinostropheus</i> Extinct genus of dinosaurs

Spinostropheus is a genus of carnivorous neotheropod theropod dinosaur that lived in the Middle Jurassic period and has been found in the Tiouraren Formation, Niger. The type and only species is S. gautieri.

<span class="mw-page-title-main">Turiasauria</span> Extinct clade of dinosaurs

Turiasauria is an unranked clade of basal sauropod dinosaurs known from Middle Jurassic to Early Cretaceous deposits in Europe, North America, and Africa.

<span class="mw-page-title-main">Camarasauridae</span> Extinct family of dinosaurs

Camarasauridae is a family of sauropod dinosaurs. Among sauropods, camarasaurids are small to medium-sized, with relatively short necks. They are visually identifiable by a short skull with large nares, and broad, spatulate teeth filling a thick jaw. Based on cervical vertebrae and cervical rib biomechanics, camarasaurids most likely moved their necks in a vertical, rather than horizontal, sweeping motion, in contrast to most diplodocids.

<span class="mw-page-title-main">Neosauropoda</span> Extinct clade of dinosaurs

Neosauropoda is a clade within Dinosauria, coined in 1986 by Argentine paleontologist José Bonaparte and currently described as Saltasaurus loricatus, Diplodocus longus, and all animals directly descended from their most recent common ancestor. The group is composed of two subgroups: Diplodocoidea and Macronaria. Arising in the early Jurassic and persisting until the Cretaceous–Paleogene extinction event, Neosauropoda contains the majority of sauropod genera, including genera such as Apatosaurus, Brachiosaurus, and Diplodocus. It also includes giants such as Argentinosaurus, Patagotitan and Sauroposeidon, and its members remain the largest land animals ever to have lived.

<span class="mw-page-title-main">Tiourarén Formation</span> Geological Formation

The Tiourarén Formation is a geological formation in the Agadez Region of Niger whose strata were originally thought to be Early Cretaceous. However, re-interpretation of the sediments showed that they are probably Middle or Late Jurassic (Bathonian-Oxfordian) in age. Other works suggested it reaches the Barremian. It is the uppermost unit of the Irhazer Group. Dinosaur remains & other vertebrates are among the fossils that have been recovered from the formation. Originally part of the "Argiles de l'Ihrazer", the Tiouaren Formation primarily comprises reddish to purple siltstones with occasional marls, limestones, and scarce channel sandstones.

<i>Nigersaurus</i> Genus of reptiles (fossil)

Nigersaurus is a genus of rebbachisaurid sauropod dinosaur that lived during the middle Cretaceous period, about 115 to 105 million years ago. It was discovered in the Elrhaz Formation in an area called Gadoufaoua, in Niger. Fossils of this dinosaur were first described in 1976, but it was only named Nigersaurus taqueti in 1999, after further and more complete remains were found and described. The genus name means "Niger reptile", and the specific name honours the palaeontologist Philippe Taquet, who discovered the first remains.

<i>Spinophorosaurus</i> Middle Jurassic genus of sauropod dinosaur

Spinophorosaurus is a genus of sauropod dinosaur that lived in what is now Niger during the Middle Jurassic period. The first two specimens were excavated in the 2000s by German and Spanish teams under difficult conditions. The skeletons were brought to Europe and digitally replicated, making Spinophorosaurus the first sauropod to have its skeleton 3D printed, and were to be returned to Niger in the future. Together, the two specimens represented most of the skeleton of the genus, and one of the most completely known basal sauropods of its time and place. The first skeleton was made the holotype specimen of the new genus and species Spinophorosaurus nigerensis in 2009; the generic name refers to what was initially thought to be spiked osteoderms, and the specific name refers to where it was found. A juvenile sauropod from the same area was later assigned to the genus.

<span class="mw-page-title-main">Eusauropoda</span> Extinct clade of dinosaurs

Eusauropoda is a derived clade of sauropod dinosaurs. Eusauropods represent the node-based group that includes all descendant sauropods starting with the basal eusauropods of Shunosaurus, and possibly Barapasaurus, and Amygdalodon, but excluding Vulcanodon and Rhoetosaurus. The Eusauropoda was coined in 1995 by Paul Upchurch to create a monophyletic new taxonomic group that would include all sauropods, except for the vulcanodontids.

References

  1. 1 2 3 Sereno, P.; et al. (November 1999). "Cretaceous Sauropods from the Sahara and the Uneven Rate of Skeletal Evolution Among Dinosaurs" (PDF). Science. 286 (5443): 1342–1347. doi:10.1126/science.286.5443.1342. PMID   10558986.
  2. Sereno, Paul. "Discoveries: Jobaria tiguidensis". Archived from the original on 8 October 2012. Retrieved 25 September 2012.
  3. 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 (3–4): 259–267. Bibcode:2009PPP...271..259R. doi:10.1016/j.palaeo.2008.10.019.
  4. Henderson, Donald (2013). "Sauropod Necks: Are They Really for Heat Loss?". PLOS ONE. 8 (10): e77108. Bibcode:2013PLoSO...877108H. doi: 10.1371/journal.pone.0077108 . PMC   3812985 . PMID   24204747.
  5. Paul, Gregory S. (2016). The Princeton Field Guide to Dinosaurs 2nd Edition. New Jersey: Princeton University Press. pp. 218–219.
  6. Could Sauropods Rear?
  7. Upchurch, P.; Barrett, P. M.; Dodson, P. (2004). "Sauropoda". The Dinosauria (2nd ed.). University of California Press.
  8. 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 . PMID   28480136.
  9. Sander, P. Martin; Christian, Andreas; Clauss, Marcus; Fechner, Regina; Gee, Carole T.; Griebeler, Eva-Maria; Gunga, Hanns-Christian; Hummel, Jürgen; Mallison, Heinrich; Perry, Steven F.; et al. (2011). "Biology of the sauropod dinosaurs: the evolution of gigantism". Biological Reviews. 86 (1): 117–155. doi:10.1111/j.1469-185X.2010.00137.x. ISSN   1464-7931. PMC   3045712 . PMID   21251189.