Vulcanodon Temporal range: Sinemurian-Pliensbachian, | |
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Skeletal diagram showing the known remains | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | † Sauropodomorpha |
Clade: | † Sauropoda |
Clade: | † Gravisauria |
Family: | † Vulcanodontidae |
Genus: | † Vulcanodon Raath, 1972 |
Type species | |
†Vulcanodon karibaensis Raath, 1972 |
Vulcanodon (meaning "volcano tooth") is an extinct genus of sauropod dinosaur from the Early Jurassic Uppermost Forest Sandstone of southern Africa. [1] The only known species is V. karibaensis. Discovered in 1969 in 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 smaller than most other sauropods, measuring approximately eleven metres (36 ft) in length. Vulcanodon is known from a fragmentary skeleton including much of the pelvic girdle, hindlimbs, 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 unidentified theropod 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.
Vulcanodon was initially thought have been a small sauropod. In 2010, Gregory S. Paul estimated its length at eleven metres, its weight at 3.5 tonnes. [2] Some books mention lower estimates of approximately 6.5 m (21 ft). [3] [4] However, in 2018, researchers have estimated a greater body mass of 10.3 metric tons (11.4 short tons). [5] The thighbone was 110 centimetres (43 in) long. [6]
As one of the earliest and basalmost sauropods, it is important for understanding the early evolution of this group. Sauropods descend from basal sauropodomorphs (informally called "prosauropods"), which were primitively bipedal (two-legged). [7] While Vulcanodon already was fully quadrupedal (four-legged), its limb proportions were intermediate between those of its prosauropod ancestors and those of later, more derived sauropods. [7] 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. [8] Unfortunately, no skull or neck of Vulcanodon is known, although it is otherwise very well known. [9]
Vulcanodon's limbs were sturdy and column-like, [10] and its forelimbs were already proportionally long, reaching 76% of hindlimb length. [11] Its lower leg, metatarsus, and toes were shortened in comparison to its bipedal ancestors, but still not as short as in later sauropods. [7] The sacrum was made out of 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 perforated pockets called pleurocoels. [6] Contrasting the many sauropod-like features of the skeleton, the pelvis was relatively primitive, reminiscent of its "prosauropod" ancestors. [7] [8] One such feature is that the brevis shelf of the ilium has a fossa, which is not found in any more derived sauropods. [12]
The hallux (the first toe of the foot) showed a large claw that was flattened laterally, as seen in "prosauropods". [6] However, the claws of the second and third toe were unusual in being nail-like and broader than deep. [10] [13] This feature was also found in the probably closely related Tazoudasaurus , but is absent in all other sauropods. [14] The feet of Vulcanodon were semiplantigrade as in later sauropods (where both the digits and part of the metatarsals contact the ground [7] ), a derived feature not found in more basal sauropods like Isanosaurus . However, they also retained primitive features, like the fact that the phalanges were not reduced. [12]
Many of the features found in sauropods that basal sauropodomorphs lack are related to the change in body size. The greatest regions affected by this are the hind limbs and pelvis. For example, an elongating of the ilium, size reduction of the lesser trochanter shelf, and semiplantigrade posture are some features that indicate the amount and positioning of leg muscles being modified. Vulcanodon possessed these features, the latter of which is seen earliest in it. However, Vulcanodon does not have reduced distal phalanges, which are seen in Shunosaurus and all more derived sauropods. This means that while the muscle positioning of its legs were changing, they had not yet reduced in the distal region of the limb. [12]
Vulcanodon is known only from a single locality on an island in Lake Kariba, the largest artificial lake in the world, in northern Zimbabwe (formerly Rhodesia). [15] The island, located west of Bumi Hills, [6] is called "Island 126/127", after early, unpublished lake charts, but has no formal name. The first bone was found by B. A. Gibson of the town of Kariba in July 1969, and an excavation team collected the specimen in October 1969, March 1970 and May 1970. In the later half of 1970, the new find was presented at a scientific symposium in Cape Town and a brief note was published. The find was formally named and described in July 1972 by paleontologist Michael Raath. [10] The name Vulcanodon (lat. Vulcanus – Roman god of fire; gr. odon – "tooth") [16] points to the fact that the skeleton was found in sandstone, that was at the time misinterpreted to be part of the Batoka Formation but is actually part of the Forest Sandstone lays a few metres below the lava flows of the Batoka Formation, and emphasizes the peculiar knife-shaped teeth that are now known to belong to a theropod. [10] The specific name, karibaensis, refers to the place of discovery on a small island in Lake Kariba. [10] It was one of the first dinosaurs found in Zimbabwe. [17]
The skeleton (catalogue number QG24) has been found weathering out of a hill slope and was partially eroded by surface exponation and plant roots, erroneously documented as sandwiched between two basalt layers. [1] It includes the pelvis and sacrum, most of the left hind limb and foot, a right thigh bone, and twelve anterior tail vertebrae. These remains pertain to a single individual as they were all found articulated (still connected together). Additionally, several disarticulated bones were found, including the right forearm and some metacarpalia and phalanges from both the right and left forefeet, probably also pertaining to this individual. [10] Later, the site was revisited by the scientists Geoffrey Bond and Michael Cooper, who were able to collect additional remains including a scapula (specimen QG152, a shoulder blade) and a fragment of a neck vertebra. [6] These remains show that more than one individual was present, and it is possible that they do not pertain to Vulcanodon at all. [18] Today, the Vulcanodon remains are stored in the Natural History Museum of Zimbabwe in Bulawayo. [6]
Raath (1972) noted the discovery of nine fragmentary carnivorous teeth near the pelvic region of the skeleton. He argued that the Vulcanodon carcass might have been embedded with the head and neck bended backwards above the pelvis, a posture called death pose that is frequently seen in dinosaur skeletons. The teeth would have been the only preserved elements of the skull. [10] However, as shown by Cooper (1984), these teeth do not pertain to Vulcanodon but to a theropod dinosaur that may have scavenged on the Vulcanodon carcass. [6]
Originally, Michael Raath (1972) described Vulcanodon not as a sauropod but as an advanced, specialized prosauropod, possibly of the family Melanorosauridae. [10] [6] 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. [10] 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. [19] Today, Vulcanodon is universally accepted to be one of the most basal (primitive) members of Sauropoda. [13] [18]
Michael Cooper (1984) erected a new family, the Vulcanodontidae, which he regarded as the "rootstock" for later sauropod families. [6] 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 . [20] 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. [11]
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. [14] [21] However, this sibling relationship between Tazoudasaurus and Vulcanodon could not be confirmed by other analyses. [22] [23]
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 . [24]
Vulcanodon in a cladogram after Nair et al., 2012: [25]
During the later part of the Lower Jurassic, southern Africa was the scene of massive volcanism, resulting in extensive lava flows (so called flood basalts) that covered much of southern Africa and Antarctica. These basalt formations are known as the Karoo-Ferrar large igneous province. Vulcanodon comes from the "Vulcanodon beds", a fossil-bearing sediment unit within the Batoka Formation, which is composed primarily of flood basalts. [26] The skeleton was found near the top of a 30-metre-thick (98 ft) bedded layer of sand- and siltstone that is over- and underlain by flood basalts. [10]
It was long assumed that Vulcanodon lived during the lowermost (earliest) part of the Jurassic (the Hettangian stage) or at the Triassic–Jurassic boundary, approximately 200 million years ago. [11] [18] [20] Therefore, it was regarded as the earliest sauropod known, until the discovery of the even older Late Triassic Isanosaurus was announced in 2000. [27] Adam Yates (2004) has recently shown that Vulcanodon is actually much younger than previously thought, dating to the uppermost (latest) part of the Lower Jurassic during the Toarcian stage, approximately 175–183 million years ago. [24] [28] Thus, it is contemporary to the closely related Tazoudasaurus. [21] As was assumed that the locality of Vulcanodon itself cannot be dated radiometrically because of weathering of the lavas, it would roughly be a contemporary to Karoo lavas from other localities, as the entire sequence of volcanic eruptions was finished within one million years. [24] In 2018 was revelated that as in 2016 Lake Kariba hosted record-low water levels the unit were accessible to be studied and confirmed that the holotype came from the uppermost Forest Sandstone, being as old as the Rhaetian or as young as the Pliensbachian, with a Sinemurian-Pliensbachian Midpoint. [1]
Vulcanodon is the only named dinosaur from the Vulcanodon beds. [26] Cooper (1984) noted that the habitat was desert-like, as indicated by aeolian (wind-blown) sands of the Forest Sandstone Formation, which underlies the "Vulcanodon beds". The sediments in which Vulcanodon was found may represent distal alluvial fan deposits which levelled off into a desert landscape, which may have contained lakes during the wet season. The individual may have roamed the shores of wadis that cut into the alluvial fan deposits, unless the carcass was transported to the locality it was found by flooding. [6]
Initially, sauropods were thought to be mainly aquatic, inhabiting lush peat swamps and being captive to the buoyancy of water to support their giant body weights. [29] In 1984, Cooper pointed out that Vulcanodon, the most primitive sauropod known at that time, lived in a desert like environment and therefore must have been terrestrial. This indicated that the large body size of sauropods, as already seen in Vulcanodon, had not evolved as an adaptation to an aquatic life style. [6]
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.
Barapasaurus is a genus of basal sauropod dinosaur from Jurassic rocks of India. The only species is B. tagorei. Barapasaurus comes from the lower part of the Kota Formation, which is of Early to Middle Jurassic age. It is therefore one of the earliest known sauropods. Barapasaurus is known from approximately 300 bones from at least six individuals, so that the skeleton is almost completely known except for the anterior cervical vertebrae and the skull. This makes Barapasaurus one of the most completely known sauropods from the early Jurassic.
Anchisaurus is a genus of basal sauropodomorph dinosaur. It lived during the Early Jurassic Period, and its fossils have been found in the red sandstone of the Upper Portland Formation, Northeastern United States, which was deposited from the Hettangian age into the Sinemurian age, between about 200 and 192 million years ago. Until recently it was classed as a member of Prosauropoda. The genus name Anchisaurus comes from the Greek αγχιanchi-; "near, close" + Greek σαυρος ; "lizard". Anchisaurus was coined as a replacement name for "Amphisaurus", which was itself a replacement name for Hitchcock's "Megadactylus", both of which had already been used for other animals.
Diplodocids, or members of the family Diplodocidae, are a group of sauropod dinosaurs. The family includes some of the longest creatures ever to walk the Earth, including Diplodocus and Supersaurus, some of which may have reached lengths of up to 42 metres (138 ft).
Melanorosaurus is a genus of basal sauropodomorph dinosaur that lived during the Late Triassic period. A omnivore from South Africa, it had a large body and sturdy limbs, suggesting it moved about on all fours. Its limb bones were massive and heavy like the limb bones of true sauropods.
Massospondylus was a genus of sauropodomorph dinosaur from the Early Jurassic. It was described by Sir Richard Owen in 1854 from remains discovered in South Africa, and is thus one of the first dinosaurs to have been named. Fossils have since been found at other locations in South Africa, Lesotho, and Zimbabwe. Material from Arizona's Kayenta Formation, India, and Argentina has been assigned to the genus at various times, but the Arizonan and Argentinian material are now assigned to other genera.
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.
Tazoudasaurus is a genus of gravisaurian, probably a vulcanodontid sauropod dinosaurs hailing from the late Early Jurassic (Toarcian), that was recovered in the "Toundoute Continental Series" located in the High Atlas Mountains of Morocco in North Africa. Along with Patagosaurus, Volkheimeria, Bagualia and Perijasaurus represents one of the few sauropods named from this stage on Gondwana, as well as the only one from Africa.
Volkheimeria is an extinct genus of sauropod dinosaurs that lived in what is now Argentina during the Early Jurassic, 178–179 million years ago. Its type and only species is Volkheimeria chubutensis.
Gryponyx is an extinct genus of massopod sauropodomorph known from southern Free State, central South Africa.
Chinshakiangosaurus is a genus of dinosaur and probably one of the most basal sauropods known. The only species, Chinshakiangosaurus chunghoensis, is known from a fragmentary skeleton found in Lower Jurassic rocks in China. Chinshakiangosaurus is one of the few basal sauropods with preserved skull bones and therefore important for the understanding of the early evolution of this group. It shows that early sauropods may have possessed fleshy cheeks.
Gongxianosaurus is a genus of basal sauropod dinosaur from the early Jurassic Period. The only species is Gongxianosaurus shibeiensis. Based on four fragmentary to complete specimens found in China, it is one of the most completely known early sauropods. The skeleton is known in large part, missing both the hand and the majority of the skull. Gongxianosaurus was firstly named and described in a short note published in 1998; however, a comprehensive description has yet to be published. Gongxianosaurus shibeiensis was named for the place it was found, near the village Shibei in Gong County.
Kotasaurus is a genus of sauropod dinosaur from the Early Jurassic period (Sinemurian–Pliensbachian). The only known species is Kotasaurus yamanpalliensis. It was discovered in the Kota Formation of Telangana, India and shared its habitat with the related Barapasaurus. So far the remains of at least 12 individuals are known. The greater part of the skeleton is known, but the skull is missing, with the exception of two teeth. Like all sauropods, it was a large, quadrupedal herbivore with long neck and tail.
The Early Jurassic sauropod dinosaurs Zizhongosaurus, Barapasaurus, Tazoudasaurus, and Vulcanodon may form a natural group of basal sauropods called the Vulcanodontidae. Basal vulcanodonts include some of the earliest known examples of sauropods. The family-level name Vulcanodontidae was erected by M.R. Cooper in 1984. In 1995 Hunt et al. published the opinion that the family is synonymous with the Barapasauridae. One of the key morphological features specific to the family is an unusually narrow sacrum.
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.
The Forest Sandstone is a geological formation in southern Africa, dating to roughly between 200 and 190 million years ago and covering the Hettangian to Sinemurian stages of the Jurassic Period in the Mesozoic Era. As its name suggests, it consists mainly of sandstone.
Anchisauria is an extinct clade of sauropodomorph dinosaurs that lived from the Late Triassic to the Late Cretaceous. The name Anchisauria was first used Haekel and defined by Galton and Upchurch in the second edition of The Dinosauria. It is a node-based taxon containing the most recent common ancestor of Anchisaurus polyzelus and Melanorosaurus readi, and all its descendants. Galton and Upchurch assigned a family of dinosaurs to the Anchisauria: the Melanorosauridae. The more common prosauropods Plateosaurus and Massospondylus were placed in the sister clade Plateosauria.
Diplodocus was a genus of diplodocid sauropod dinosaurs, whose fossils were first discovered in 1877 by S. W. Williston. The generic name, coined by Othniel Charles Marsh in 1878, is a Neo-Latin term derived from Greek διπλός (diplos) "double" and δοκός (dokos) "beam", in reference to the double-beamed chevron bones located in the underside of the tail, which were then considered unique.
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.
The hyposphene-hypantrum articulation is an accessory joint found in the vertebrae of several fossil reptiles of the group Archosauromorpha. It consists of a process on the backside of the vertebrae, the hyposphene, that fits in a depression in the front side of the next vertebrae, the hypantrum. Hyposphene-hypantrum articulations occur in the dorsal vertebrae and sometimes also in the posteriormost cervical and anteriormost caudal vertebrae.