Dravidosaurus

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Dravidosaurus
Temporal range: Late Cretaceous, 90–86 Ma
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Ornithischia
Suborder: Stegosauria
Genus: Dravidosaurus
Species:
D. blanfordi
Binomial name
Dravidosaurus blanfordi
Yadagiri & Ayyasami, 1979

Dravidosaurus (meaning "Dravidanadu lizard", Dravidanadu being a region in the southern part of India where the remains were discovered) is a controversial genus of prehistoric reptile. It was first described as the last surviving stegosaurian, the group of "plated" dinosaurs. With an estimated length of three metres (10 ft), it would have also been the smallest member of the group.[1] More recent studies, however, have shown that the bones actually belonged to a plesiosaurian marine reptile, and that none of the remains are demonstrably dinosaurian in origin.[2]

Dravidosaurus lived in the Late Cretaceous period (Coniacian stage) of what is now India. It is only known from disassociated remains that were originally described as comprising a partial skull, a tooth, a sacrum, an ilium, an ischium, a dermal plate, and a spike. The badly weathered remains were discovered in marine deposits near Ariyalur in the state of Tamil Nadu in South India. They were in 1979 named by P.M. Yadagiri and Krishnan Ayyasami as the type species Dravidosaurus blanfordi, the specific name honouring William Thomas Blanford. The holotype partial skull is catalogued as GSI SR Pal 1, while other specimens are catalogued GSI SR Pal 2-7.[3]

In 1991, Sankar Chatterjee visited the site and claimed, without presenting concrete morphological evidence, that Dravidosaurus was based on plesiosaurian pelvic and hindlimb elements, the species being a nomen dubium.[4] However, this claim was rejected by Galton and Upchurch (2004), who noted that the skull, tooth and plate of Dravidosaurus are certainly not plesiosaurian as illustrated.[5] Galton and Ayyasami (2017) reaffirmed the stegosaurian classification of Dravidosaurus, claiming the remains do not look like plesiosaurian pelvic and hindlimb elements. They announced that stegosaurian remains from the Dravidosaurus type locality are under study by one of the original describers of Dravidosaurus.[6] The tooth referred to Dravidosaurus appears to come from a notosuchian.[7]

See also[edit]

References[edit]

  1. ^ Galton P.M., and Upchurch P., (2004). "Stegosauria." In D. B. Weishampel, P. Dodson, and H. Osmólska (eds.), The Dinosauria (2nd edition), University of California Press, Berkeley 343-362.
  2. ^ Wilson, J. A., Barrett, P. M., & Carrano, M. T. (2011). An associated partial skeleton of Jainosaurus cf. septentrionalis (Dinosauria: Sauropoda) from the Late Cretaceous of Chhota Simla, central India. Palaeontology, 54(5), 981-998.
  3. ^ Yadagiri, P., and Ayyasami, K., (1979). "A new stegosaurian dinosaur from Upper Cretaceous sediments of south India." Journal of the Geological Society of India, 20(11): 521-530.
  4. ^ Chatterjee, S., and Rudra, D. K. (1996). "KT events in India: impact, rifting, volcanism and dinosaur extinction," in Novas & Molnar, eds., Proceedings of the Gondwanan Dinosaur Symposium, Brisbane, Memoirs of the Queensland Museum, 39(3): iv + 489–731 : 489-532
  5. ^ Peter M. Galton; Paul Upchurch (2004). "Stegosauria". In David B. Weishampel; Peter Dodson; Halszka Osmólska (eds.). The Dinosauria (2nd ed.). Berkeley: University of California Press. pp. 343–362. ISBN 0-520-24209-2.
  6. ^ Peter M. Galton; Krishnan Ayyasami (2017). "Purported latest bone of a plated dinosaur (Ornithischia: Stegosauria), a "dermal plate" from the Maastrichtian (Upper Cretaceous) of southern India". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen. 285 (1): 91–96. doi:10.1127/njgpa/2017/0671.
  7. ^ http://www.dinosaurhome.com/rising-sea-levels-doomed-the-stegosaurs-15012.html#comment-11495