Barapasaurus
| Barapasaurus Temporal range: Early Jurassic?,
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| Life restoration | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | †Sauropodomorpha |
| Clade: | †Sauropoda |
| Clade: | †Gravisauria |
| Genus: | †Barapasaurus Jain et al., 1975 |
| Species: | †B. tagorei
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| Binomial name | |
| †Barapasaurus tagorei Jain et al, 1975
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Barapasaurus (/bəˌrɑːpəˈsɔːrəs/ bə-RAH-pə-SOR-əs) 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.
Discovery and naming
All known fossils come from a single locality in the vicinity of the village of Pochampally Pin Code: 442504, bordering Telangana (Pochampally Sironcha Taluka, Gadchiroli District, Vidarbha, Maharastra, in central India).[1] The first bones were discovered in 1958, but most specimens were unearthed in 1960 and 1961.[2] In 1975, the finds were described scientifically by palaeontologist Sohan Lal Jain and colleagues.[1] In 2010, a more detailed osteological description was published by Bandyopadhyay and colleagues.[2] The material is archived in the palaeontological collection of the Indian Statistical Institute (ISI), while a majority of the bones are part of a mount at the Geological Museum of the ISI.[2]
Etymology
The name Barapasaurus ("big-legged lizard") is derived from bara meaning 'big' and pa meaning 'leg' in several Indian languages including Bengali; the Greek word sauros means 'lizard'.[1] This name was used as a nomen nudum since a femur measuring over 1.7 m was unearthed at 1961.[1] The specific name tagorei means 'Tagore's', which honours Bengali poet, writer, painter, and musician Rabindranath Tagore. The first year of fieldwork was carried out in the centenary year of Tagore's birth.[1]
Fossil record
Barapasaurus tagorei is known from a large bone bed found in the Lower Kota Formation, containing approximately 300 bones from at least six individuals of various ages. No remains of the skull, other than teeth, have been found.[2] The age of this fossil site is disputed, because no volcanic rocks whose age can be determined by radiometric dating are associated with the Kota Formation and its age can only be estimated by biostratigraphic comparisons to other rock layers, which is made difficult by the lack of reliable index fossils in the formation. The age has generally been interpreted as Early Jurassic, with the Lower Kota Formation in particular dating to the Sinemurian to Pliensbachian, roughly 184–200 million years ago. However, some studies have argued that the Kota Formation dates to the Middle Jurassic or even later.[4][5]
Taphonomy
The approximately 300 bones were found together with large trunks of trees scattered over an area of 276 square meters. Although one of the specimens was found partly articulated, most bones were found disarticulated. Because there are six left femora, the total number of individuals is at least six.[2]
Bandyopadhyay and colleagues (2002, 2010) interpret this assemblage as a herd that died due to a catastrophic event, likely a flood. This flood could have unearthed the trees and transported both trees and Barapasaurus a distance before they began to decompose. After decomposition progressed, the bones began to disarticulate. The disarticulated skull bones were removed by the water stream because they were light, leaving only the heavy postcranial bones at the site, which would explain why no skull bones were found.[2]
Description
Although a very early and unspecialised sauropod, Barapasaurus shows the building plan typical for later, more derived sauropods: the cervical vertebrae were elongated, resulting in a long neck. The trunk was short and holds columnar limbs which indicate an obligate quadrupedal posture.[3][2] Even the size, which is estimated at approximately 12-14 meters long and 7 tonnes in weight,[6][7] is comparable with that of later sauropods.[3]
The vertebral column already shows many traits that are typical for later sauropods which allowed them to attain great body sizes, although in later sauropods these traits are much more developed. The central and neural spines show early hints of hollowing as a weight-saving measure. The dorsal vertebrae are stabilised with hyposphene-hypantrum articulations, accessory projections that link the vertebrae with each other. The sacrum is strengthened through an additional fourth sacral vertebra.[2]
From the skull, only three whole teeth and three crowns are known. The largest known tooth is 5.8 cm in height. Like that of later sauropods, the teeth are spoon shaped and show wrinkled enamel. A basal trait is the coarse serration.[2]
Classification
Cladogram of basal Sauropoda
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The relationships of this genus within the Sauropoda are debated. When first described in 1975, it was not attributed to one specific group at all, although the presence of many basal, prosauropod-like features was noted.[1] Since 1984, Barapasaurus was united with another early sauropod, Vulcanodon, in a family called Vulcanodontidae, although this family was declared invalid by Paul Upchurch in 1995 because it was recognised as polyphyletic. Upchurch erected a clade named Eusauropoda that includes all known sauropods except some very basal forms. While Vulcanodon was classified outside the Eusauropoda, Barapasaurus was classified inside it, which means that Barapasaurus is more derived than Vulcanodon.[2][8] Although Upchurch's classification was accepted by most palaeontologists, a recent study from Bandyopadhyay and colleagues came to a contrary conclusion: these palaeontologists stated that Barapasaurus was in fact more basal than Vulcanodon and removed it from Eusauropoda.[2]
Habitat
Barapasaurus comes from clay and sandstone that belongs to the lower part of the Kota Formation. Other vertebrates of this part include another early sauropod, Kotasaurus, as well as the mammals Kotatherium, Indotherium and Indozostrodon. The upper part of the Kota Formation additionally contained a pterosaur (Campylognathoides), a turtle, two rhynchocephalians, a lepidosaur and some mammals.[2]
References
- ^ a b c d e f Jain, S. L.; T. S. Kutty; T. Roy-Chowdhury; S. Chatterjee (18 February 1975). "The Sauropod Dinosaur from the Lower Jurassic Kota Formation of India". Proceedings of the Royal Society B. 188 (1091): 221–228. Bibcode:1975RSPSB.188..221J. doi:10.1098/rspb.1975.0014. ISSN 1471-2954. S2CID 84957608. Retrieved 13 October 2012.
- ^ a b c d e f g h i j k l m Bandyopadhyay, Saswati; David D. Gillette; Sanghamitra Ray; Dhurjati P. Sengupta (2010). "Osteology of Barapasaurus tagorei (Dinosauria: Sauropoda) from the Early Jurassic of India". Palaeontology. 53 (3): 533–569. Bibcode:2010Palgy..53..533B. doi:10.1111/j.1475-4983.2010.00933.x. ISSN 1475-4983.
- ^ a b c Jain, S. L.; T. S. Kutty; T. Roy-Chowdhury; S. Chatterjee (1979). "Some characteristics of Barapasaurus tagorei, a sauropod dinosaur from the Lower Jurassic of Deccan, India". Proceedings of the IV International Gondwana Symposium, Calcutta. Vol. 1. pp. 204–216.
- ^ Parmar, Varun; Prasad, Guntupalli V. R.; Kumar, Deepak (2013). "The first multituberculate mammal from India". Naturwissenschaften. 100 (6): 515–523. Bibcode:2013NW....100..515P. doi:10.1007/s00114-013-1047-0. eISSN 1432-1904. ISSN 0028-1042. PMID 23644519. S2CID 253638698.
- ^ Pol, D.; Gomez, K.; Holwerda, F.H.; Rauhut, O.W.M.; Carballido, J.L. (2022). "Sauropods from the Early Jurassic of South America and the Radiation of Eusauropoda". In Otero, A.; Carballido, J.L.; Pol, D. (eds.). South American Sauropodomorph Dinosaurs. Record, Diversity and Evolution. Springer. pp. 131–163. doi:10.1007/978-3-030-95959-3. ISBN 978-3-030-95958-6. ISSN 2197-9596. S2CID 248368302.
- ^ Glut, Donald F. (1997). Dinosaurs, the encyclopedia. McFarland & Company, Inc. Publishers. ISBN 978-0-375-82419-7.
- ^ Paul, Gregory S. (2010). The Princeton Field Guide To Dinosaurs. New Jersey: Princeton University Press. p. 173. ISBN 9780691137209.
- ^ Upchurch, Paul (29 September 1995). "The Evolutionary History of Sauropod Dinosaurs". Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 349 (1330): 365–390. doi:10.1098/rstb.1995.0125. ISSN 1471-2970.
External links
- Barapasaurus Archived 7 September 2015 at the Wayback Machine
- Barapasaurus
