Vulcanodon

*Vulcanodon karibaensis*

***Vulcanodon*** (meaning "volcano tooth") is an extinct genus of sauropod dinosaur from the Early Jurassic of southern Africa. The only known species is *V. karibaensis*. Discovered in 1969 in Rhodesia (now known as Zimbabwe), it was regarded as the earliest known sauropod for decades, and is still one of the most primitive sauropods that has been discovered. As a quadrupedal, ground- dwelling herbivore, *Vulcanodon* already showed the typical sauropod body plan with column-like legs and a long neck and tail. It was much smaller than most other sauropods, measuring approximately 6.5 metres (20 ft) in length. *Vulcanodon* is known from a fragmentary skeleton including much of the pelvic girdle, hind limbs, forearms, and tail, but lacking the trunk and neck vertebrae as well as the skull. Originally, this genus was believed to be a prosauropod because of the knife-shaped teeth found near its fossils, which fit in with the idea that prosauropods were omnivorous. Scientists now know that the teeth belonged to an unidentifiedtheropod that may have scavenged on the *Vulcanodon* carcass. *Vulcanodon* is now known to be a true sauropod. Upon the discovery of the related *Tazoudasaurus*, both animals were unified in the family Vulcanodontidae, though this has not been universally accepted.

## Etymology

*Vulcanodon* was named by Michael Raath in 1972. The name points to the fact that the skeleton was found in a small body of sandstone that is sandwiched between two lava flows, and emphasizes the peculiar knife-shaped teeth that are now known to belong to a theropod. The species name, *karibaensis*, refers to the place of discovery on a small island in Lake Kariba.

## Description

*Vulcanodon* was a small sauropod, measuring approximately 6.5 meters (21 feet) in length. As one of the earliest and basalmost sauropods, it is important for understanding the early evolution of this group. Sauropods descend from basal sauropodomorphs, which were primitively bipedal. While *Vulcanodon* already was fully quadrupedal , its limb proportions were intermediate between those of its prosauropod ancestors and those of later, more derived sauropods. Its forelimbs were much more similar to later sauropods than basal sauropodomorphs because they are straight, much more gracile, and the proximal end of the ulna is v-shaped. Unfortunately, no skull or neck of *Vulcanodon* is known, although it is otherwise very well-known.

### Hindlimbs and pelvis

Vulcanodon's limbs were sturdy and column-like, and its forelimbs were already proportionally long, reaching 76% of hindlimb length. Its lower leg, metatarsus, and toes were shortened in comparison to its bipedal ancestors, but still not as short as in later sauropods. The posture of the foot is unclear; it either was digitigrade as in "prosauropods" (only the digits touch the ground) or semiplantigrade as in later sauropods (both the digits and parts of the metatarsals touch the ground). The sacrum was made out four fused sacral vertebrae; "prosauropods" possessed only three sacrals. The tail vertebra bodies already showed an incipient excavation of their lateral sides, saving weight and giving them a waisted appearance when viewed from below. In later sauropods, this excavations were enlarged to form extensive pockets called pleurocoels. Contrasting the many sauropod-like features of the skeleton, the pelvis was relatively primitive, reminiscent of its "prosauropod" ancestors.

The hallux (the first toe of the foot) showed a large claw that was flattened laterally, as seen in "prosauropods". However, the claws of the second and third toe were unusual in being nail-like and broader than deep. This feature was also found in the probably closely related *Tazoudasaurus*, but is absent in all other sauropods.

## Classification

Originally, Michael Raath (1972) described Vulcanodon not as a sauropod but as an advanced, specialized prosauropod, possibly of the family Melanorosauridae. According to Raath, the sauropod-like limb proportions in Vulcanodon evolved independently from those of true sauropods (through convergent evolution). He argued that primitive features of the pelvis as well as the knife-shaped teeth preclude a classification within the Sauropoda. The teeth, however, are now known to belong to a theropod. Arthur Cruickshank (1975) was the first to show that Vulcanodon was indeed a sauropod, arguing that the fifth metatarsal bone was equally long as the remaining metatarsals, a condition seen in other sauropods but not in prosauropods. Today, Vulcanodon is universally accepted to be one of the most basal (primitive) members of Sauropoda.
Michael Cooper (1984) erected a new family, the Vulcanodontidae, which he regarded as the "rootstock" for later sauropod families. Originally, the Vulcanodontidae included Vulcanodon and the Indian Barapasaurus, but subsequent studies attributed a number of other, much more fragmentary early sauropod genera to this family, including Ohmdenosaurus and Zizhongosaurus. Paul Upchurch (1995) showed that Barapasaurus was more closely related to later, more advanced sauropods than to Vulcanodon, rendering the Vulcanodontidae polyphyletic and therefore invalid.
The exact relationships with other basal sauropod genera remain unclear. Ronan Allain and colleagues (2004, 2008) found that Vulcanodon is most closely related to Tazoudasaurus, a newly discovered sauropod genus from Morocco. These researchers suggested reintroducing the name Vulcanodontidae to name the clade containing Vulcanodon and Tazoudasaurus. However, this sibling relationship between Tazoudasaurus and Vulcanodon could not be confirmed by other analyses.
Adam Yates (2004) described a single sauropod tail vertebra from the Upper Elliot Formation of South Africa that may belong to a genus closely related to Vulcanodon. The Upper Elliot Formation is famous for its abundant fossils of the prosauropod Massospondylus.

## JPInstitute.com Description

Vulcanodon was a very early member of the long-necked sauropod family. It lived in Africa at the time that the first sauropods were evolving from the more primitive prosauropod dinosaurs. Interestingly, this animal was discovered in the stomach area of the predatory dinosaur that had eaten it.
The family that this dinosaur founded is considered to be at the foundation of both the diplodocids and the camarasaurs. It has been argued that it is more a prosauropod than a sauropod. It is possible that Vulcanodon was an evolutionary step between Plateosaurus and the later sauropods.

## Links

https://web.archive.org/web/20080706034422/http://kids.yahoo.com/dinosaurs/428--Vulcanodon