Vulcanodon
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Vulcanodon in a plastic representation, JuraPark in Solec Kujawski , Poland |
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| Temporal occurrence | ||||||||||
| Lower Jurassic ( Toarcium ) | ||||||||||
| 182.7 to 174.1 million years | ||||||||||
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| Vulcanodon | ||||||||||
| Raath , 1972 | ||||||||||
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Vulcanodon ("volcanic tooth") is a genus of dinosaurs from the group of sauropods thatlived in southern Africaduring the early Jurassic . The only species is V. karibaensis . So far, only a single, fragmentary skeleton is known, which was discovered in 1969 on a small island in the Kariba reservoir in Zimbabwe (formerly Rhodesia ). The name Vulcanodon refers to the fact that the sandstone layer that housed the skeleton isborderedby two lava flows . Vulcanodonis one of the most original known sauropods, but like other sauropods already walked on four legs and showed the typical construction plan for sauropods with columnar legs, long neck and tail. The only skeleton encompasses most of the pelvic girdle, hind legs, forearm and tail, while the trunk and cervical spine and skull are absent.
Originally Vulcanodon was classified outside of the sauropods, as a prosauropod possibly belonging to the Melanorosauridae family . This assignment was based on primitive features such as the structure of the pelvis and the knife-like teeth, which suggest a carnivorous or omnivorous diet. Today, however, it is known that these teeth belonged to an unidentified theropod who may have been a scavenger on the Vulcanodon carcass. Today Vulcanodon is considered an original representative of the sauropods. Some paleontologists put the genus together with the related Tazoudasaurus in a family called Vulcanodontidae , but this has not been generally accepted.
Naming
Vulcanodon ( Latin Vulcanus - Roman god of fire; Greek odon - "tooth") was named by Michael Raath in 1972. The name refers to the fact that the skeleton was found embedded in a layer of sandstone, which is enclosed between two lava flows . In addition, the name refers to the knife-shaped teeth, which, as it turned out later, do not belong to Vulcanodon at all . The second part of the species name, karibaensis , refers to the Kariba reservoir.
description
Vulcanodon is one of the sauropodomorpha , a group of herbivorous dinosaurs that separated from the carnivorous theropods early in the evolution of the dinosaurs . The original sauropodomorpha are traditionally grouped together as prosauropods . Most prosauropods, such as Plateosaurus , were, like the theropods, two-legged ( biped ), with the arms used for grasping. During the Jurassic, an advanced group of the Sauropodomorpha, the Sauropoda, became the dominant group of terrestrial herbivores; all prosauropods died out during the Jurassic. Unlike their ancestors, sauropods were four-legged ( quadruped ), which enabled them to be taller and have a greatly elongated neck. Numerous modifications of the skeletal structure, which appear for the first time in original sauropods such as Vulcanodon , are related to this transition from a two-legged to a four-legged way of life. Vulcanodon was already four-legged like other sauropods, but still showed a number of primitive features typical of prosauropods. As one of the most original known sauropods, the genus is of great importance for understanding the origin and early evolution of the sauropods.
With an estimated length of 6.5 meters, it was a comparatively small sauropod; the physique with the barrel-shaped body, the long neck and tail and the small head, however, corresponded to that of other sauropods. Front and rear legs were sturdy and columnar, with the front legs probably accounting for 76% of the length of the hind legs, making them significantly longer than those of two-legged prosauropods. The lower legs, metatarsus, and toes were shorter than in prosauropods, but not as shortened as in more advanced sauropods. It is controversial whether the hind foot was digitigrad as in prosauropods (only the toes touched the ground) or semidigitigrad as in sauropods (both the toes and parts of the metatarsus touched the ground). The vertebral bodies of the caudal vertebrae were already indented laterally to save weight. In later sauropods, these indentations were replaced by deep hollows called pleurocoels. The sacrum was composed of four sacral vertebrae, while the original Sauropodomorpha only had three sacral vertebrae. In contrast to the numerous sauropod-like features of the skeleton, the pelvis was primitive and resembled that of the prosauropods.
The hallux , the first toe of the foot, showed an enlarged, laterally flattened claw, as was also found in prosauropods. The claws on the second and third toes were unusual; these were nail-like and wider than deep. This feature is also found in the probably closely related Tazoudasaurus , but was absent in all other sauropods.
classification
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Michael Raath (1972) originally described Vulcanodon not as a sauropod, but as an advanced, specialized prosauropod, possibly belonging to the Melanorosauridae family . Raath argued that the sauropod-like leg proportions evolved independently of each other in the Vulcanodon and the sauropods ( convergent evolution ). The primitive structure of the pelvis as well as the knife-shaped teeth would rule out belonging to the sauropods. Today, however, it is known that the teeth belong to a theropod. In 1975 Arthur Cruickshank was the first to prove that it belonged to the sauropods: As the researcher argued, the length of the fifth metatarsal corresponded to the rest, a characteristic typical of sauropods that prosauropods lack. Today's consensus confirms Vulcanodon as one of the most original known representatives of the sauropods.
In 1984 Michael Cooper set up a new family, the Vulcanodontidae , which, according to this researcher, formed the "rhizome" from which the later sauropod families emerged. Originally, in addition to Vulcanodon, only the Indian Barapasaurus was ascribed to the Vulcanodontidae ; Subsequent studies, however, made a number of other early sauropods known only by a few fragmentary bones 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 , which means that the Vulcanodontidae are polyphyletic and the family is therefore invalid.
The exact relationship to other original sauropods remains unclear. Ronan Allain and colleagues (2004, 2008) found that Vulcanodon was most closely related to Tazoudasaurus , a newly discovered genus from Morocco . These researchers suggested reintroducing the name Vulcanodontidae as a clade that includes only Vulcanodon and Tazoudasaurus . However, other studies could not confirm that Tazoudasaurus and Vulcanodon were closely related.
Adam Yates (2004) described a single caudal vertebra from the Upper Elliot Formation of South Africa , which could possibly have belonged to a sauropod genus closely related to Vulcanodon . The Upper Elliot Formation is famous for its rich finds of the prosauropod Massospondylus .
History of discovery and research
 
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The location on "Island 126/127" in the Kariba reservoir , Zimbabwe
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The only known fossils come from an island in the Kariba reservoir of the Zambezi in northern Zimbabwe (formerly Rhodesia ), one of the largest reservoirs in the world. The island to the west of Bumi Hills is referred to as "Island 126/127" according to early, unpublished nautical charts, but has no formal name. The first bone chewing out of a hillside was discovered in July 1969 by BA Gibson, a resident of Kariba City . In October of the same year, an excavation team set out to retrieve the fossils; further excavations took place in March and May 1970. In July 1970, the find was presented to the scientific society for the first time at a symposium with the main topic " Stratigraphy and paleontology of South Africa" in Cape Town . A preliminary report was published later that year. In 1972 the first scientific description by the paleontologist Michael Raath finally appeared .
Parts of the skeleton (copy number QG24) were lost before the discovery, as they were partly exposed on the surface of the site and partly eroded by plant roots . The recovered fossils include the pelvis and sacrum, most of the left hind leg and foot, a right femur, and 12 anterior caudal vertebrae. These remains can be attributed to a single individual, as they were still found in their original skeletal system. In addition, various bones outside the skeletal system were found, which are probably also attributable to this individual, including the right forearm and various metacarpal and finger bones from the left and right hand skeleton. Later, the scientists G. Bond and Michael Cooper visited the site again and were able to secure further fossils in a subsequent excavation, including a shoulder blade and a fragment of a cervical vertebra. These remains indicate that more than one individual was present at the site; possibly the shoulder blade and the cervical vertebra belong to a different genus. Today the fossils are kept in the collection of the Natural History Museum of Zimbabwe in Bulawayo .
Raath (1972) reports the discovery of nine fragmentary knife-shaped, carnivorous teeth near the pelvic region of the skeleton. According to Raath's imagination, the neck and head could have curved backwards after death, so that the skull came to lie directly above the pelvis - this position, known as the death pose , is found in numerous other dinosaur skeletons. The teeth are thus the only remaining elements of the otherwise missing skull. Cooper (1984) showed, however, that the teeth did not belong to Vulcanodon , but to a theropod dinosaur that may have acted as a scavenger on the Vulcanodon carcass.
Geology, age and habitat
During the later Lower Jurassic, southern Africa was the scene of extensive volcanism . Large amounts of thin liquid lava, which solidified into so-called flood basalts , poured over a large part of southern Africa and formed today's basalt formations of the Karoo-Ferrar Large Igneous Province . Vulcanodon comes from the Vulcanodon beds ("Vulcanodon layers"), a fossil-containing sediment unit within the Batoka Formation, which is mainly composed of flood basalts . The skeleton was found in the upper area of a 30 meter thick layer of sand and siltstones , which is overlaid and underlain by flood basalts.
It has long been assumed that Vulcanodon lived about 200 million years ago during the Hettangian , the lowest (oldest) level of the Jurassic, or even at the time of the Triassic-Jurassic border . This made the genus the earliest known sauropod until the even older Isanosaurus from the Upper Triassic of Thailand was described in 2000 . Adam Yates showed in 2004 that Vulcanodon is actually much younger than previously assumed and dates to the Toarcian , the uppermost (youngest) stage of the Lower Jurassic, about 175-183 million years ago. The genus thus lived at the same time as the closely related Tazoudasaurus . The Vulcanodon site itself cannot be dated radiometrically because of the advanced weathering of the basalts . Yates argues, however, that the volcanic eruptions were completed within a million years - thus the basalts can be assumed to be about the same time as Karoo basalts from other locations.
Vulcanodon is the only dinosaur from the Vulcanodon beds described with a scientific name . Cooper (1984) suggested that the sauropod lived in a desert-like environment, as indicated by the aeolian (wind-blown) sands of the Forest Sandstone Formation , which follow directly below the Vulcanodon beds . The sediments in which Vulcanodon was found could be distal deposits of alluvial fans . The Vulcanodon individual may have lived on the banks of wadis cut into the alluvial fan. Alternatively, the carcass could have been transported to its embedding location by a flood event.
In the beginning, sauropods were considered to be aquatic animals that populated lush swamps and relied on the buoyancy of the water to support their gigantic body mass. In 1984, Cooper determined that Vulcanodon - the most original sauropod known at the time - lived in a desert-like habitat and therefore lived on land. This evidence would show that the unusual body size of the sauropods, as it was already shown in Vulcanodon , was not an adaptation to an aquatic way of life.
supporting documents
- ↑ Donald F. Glut : Dinosaurs. The Encyclopedia. McFarland, Jefferson NC et al. 1997, ISBN 0-89950-917-7 , pp. 975-977: Vulcanodon.
- ↑ a b c d e f g h i Michael A. Raath: Fossil vertebrate studies in Rhodesia: a new dinosaur (Reptilia, Saurischia) from near the Triassic-Jurassic boundary. In: Arnoldia. Vol. 5, 1972, ISSN 0066-7781 , pp. 1-37, here pp. 1-2, 4.
- ↑ Adam M. Yates: Basal Sauropodomorpha: The "Prosauropods". In: Michael K. Brett-Surman, Thomas R. Holtz Jr. , James O. Farlow (Eds.): The Complete Dinosaur. 2nd edition. Indiana University Press, Bloomington IN 2012, ISBN 978-0-253-35701-4 , pp. 425-443.
- ↑ a b c Jeffrey A. Wilson: Overview of Sauropod Phylogeny and Evolution. In: Kristina Curry A. Rogers, Jeffrey A. Wilson (Eds.): The Sauropods. Evolution and Paleobiology. University of California Press, Berkeley CA et al. 2005, ISBN 0-520-24623-3 , pp. 15–49, here pp. 27–31, digitized version (PDF; 384.37 KB) .
- ↑ a b c d e f g h i j Michael R. Cooper: A reassessment of Vulcanodon karibaensis Raath (Dinosauria: Saurischia) and the origin of the Sauropoda. In: Palaeontologia Africana. Vol. 25, 1984, ISSN 0078-8554 , pp. 203-231.
- ^ Prehistoric Life. The definitive visual history of Life on Earth. DK Publishing, New York NY 2012, ISBN 978-0-7566-9910-9 , p. 266.
- ↑ Thomas R. Holtz Jr .: Supplementary Information. to: Thomas R. Holtz Jr .: Dinosaurs. The most complete, up-to-date Encyclopedia for Dinosaur Lovers of all ages. Random House, New York NY 2007, ISBN 978-0-375-82419-7 , p. 27, online (PDF; 184.08 KB) .
- ↑ a b c Paul Upchurch : The Evolutionary History of Sauropod Dinosaurs. In: Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences. Vol. 349, No. 1330, 1995, ISSN 0080-4622 , pp. 365-390, doi : 10.1098 / rstb.1995.0125 .
- ↑ a b Jeffrey A. Wilson, Paul C. Sereno : Early Evolution and Higher-level Phylogeny of Sauropod Dinosaurs (= Journal of Vertebrate Paleontology. Vol. 18, Supplement to No. 2 = Society of Vertebrate Paleontology. Memoir. Vol. 5 , ISSN 1062-161X ). Society of Vertebrate Paleontology, Chicago IL 1998, pp. 8, 13, doi : 10.1080 / 02724634.1998.10011115 .
- ↑ a b c Ronan Allain, Najat Aquesbi: Anatomy and phylogenetic relationships of Tazoudasaurus naimi (Dinosauria, Sauropoda) from the late Early Jurassic of Morocco. In: Geodiversitas. Vol. 30, No. 2, 2008, ISSN 1280-9659 , pp. 345-424, here pp. 403, 404.
- ^ A b c Paul Upchurch, Paul M. Barrett , Peter Dodson : Sauropoda. In: David B. Weishampel , Peter Dodson, Halszka Osmólska (eds.): The Dinosauria . 2nd edition. University of California Press, Berkeley CA et al. 2004, ISBN 0-520-24209-2 , pp. 259-324, here p. 298.
- ^ A b John S. McIntosh: Sauropoda. In: David B. Weishampel, Peter Dodson, Halszka Osmólska (eds.): The Dinosauria . University of California Press, Berkeley CA et al. 1990, ISBN 0-520-06726-6 , pp. 345-401, here p. 376.
- ↑ a b Ronan Allain, Najat Aquesbi, Jean Dejax, Christian Meyer, Michel Monbaron, Christian Montenat, Philippe Richir, Mohammed Rochdy, Dale Russell , Philippe Taquet : A basal sauropod dinosaur from the Early Jurassic of Morocco. In: Comptes Rendus Palevol. Vol. 3, No. 3, 2004, ISSN 1631-0683 , pp. 199-208, doi : 10.1016 / j.crpv.2004.03.001 , digital version (PDF; 413.28 KB) .
- ↑ Cecilia Apaldetti, Ricardo N. Martinez, Oscar A. Alcober, Diego Pol: A New Basal Sauropodomorph (Dinosauria: Saurischia) from Quebrada del Barro Formation (Marayes-El Carrizal Basin), Northwestern Argentina. In: PLoS ONE . Vol. 6, No. 11, 2011, e26964, doi : 10.1371 / journal.pone.0026964 .
- ↑ Kristian Remes, Francisco Ortega, Ignacio Fierro, Ulrich Joger , Ralf Kosma, José Manuel Marín Ferrer, Oumarou Amadou Ide, Abdoulaye Maga: A New Basal Sauropod Dinosaur from the Middle Jurassic of Niger and the Early Evolution of Sauropoda. In: PLoS ONE. Vol. 4, No. 9, 2009, e6924, doi : 10.1371 / journal.pone.0006924 .
- ↑ a b c Adam M. Yates, P. John Hancox, Bruce S. Rubidge: First record of a sauropod dinosaur from the upper Elliot Formation (Early Jurassic) of South Africa. In: South African Journal of Science. Vol. 100, No. 9/10, 2004, ISSN 0038-2353 , pp. 504-506, digital version (PDF; 589.44 KB) .
- ^ A b David B. Weishampel, Paul M. Barrett, Rodolfo Coria , Jean Le Loeuff, Xing Xu , Xijin Zhao , Ashok Sahni, Elizabeth Gomani, Christopher R. Noto: Dinosaur distribution (Late Triassic, Africa). In: David B. Weishampel, Peter Dodson, Halszka Osmólska (eds.): The Dinosauria . 2nd edition. University of California Press, Berkeley CA et al. 2004, ISBN 0-520-24209-2 , pp. 517-683, here p. 535.
- ↑ Eric Buffetaut , Varavudh Suteethorn, Gilles Cuny, Haiyan Tong, Jean Le Loeuff, Sasidhorn Khansubha, Sutee Jongautchariyakul: The earliest known sauropod dinosaur. In: Nature . Vol. 407, No. 6800, 2000, pp. 72-74, doi : 10.1038 / 35024060 .
- ↑ Jeffrey A. Wilson: Integrating ichnofossil and body fossil records to estimate locomotor posture and spatiotemporal distribution of early sauropod dinosaurs: a stratocladistic approach. In: Paleobiology. Vol. 31, No. 3, 2005, ISSN 0094-8373 , pp. 400-423, here p. 406, doi : 10.1666 / 0094-8373 (2005) 031 [0400: IIABFR] 2.0.CO; 2 .
- ↑ Donald M. Henderson: Tipsy punters: sauropod dinosaur pneumaticity, buoyancy and aquatic habits. In: Proceedings of the Royal Society of London. Series B: Biological Sciences. Vol. 271, Supplement 4, 2004, ISSN 0080-4622 , pp. S180-S183, doi : 10.1098 / rsbl.2003.0136 , digital version (PDF; 268.74 KB) .
