Callovosaurus

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Callovosaurus
Temporal range: Callovian
~164  Ma
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The Quarterly journal of the Geological Society of London (13936882312).jpg
Illustration of the holotype femur
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Ornithischia
Clade: Ornithopoda
Family: Dryosauridae
Genus: Callovosaurus
Galton, 1980
Species:
C. leedsi
Binomial name
Callovosaurus leedsi
Galton, 1980 (Lydekker, 1889)
Synonyms

Callovosaurus (meaning "Callovian lizard") is a genus of iguanodontian dinosaur known from most of a left thigh bone discovered in Middle Jurassic-age rocks of England. At times, it has been considered dubious or a valid genus of basal iguanodontian, perhaps a dryosaurid.

Contents

History and description

Life restoration Callovosaurus.jpg
Life restoration

Callovosaurus is based on BMNH  R1993, a nearly complete left thigh bone. This specimen was collected from the middle Callovian–age (Middle Jurassic) Peterborough Member (former Lower Oxford Clay) of the Oxford Clay Formation of Fletton, near Peterborough in Cambridgeshire, England. The bone is 28 centimetres (0.92 ft) long, and is estimated to have belonged to an animal approximately 2.5 m (8.2 ft) in length. A partial shin bone from the same site or nearby, SMC  J.46889, may also belong to Callovosaurus. [1]

The type species, C. leedsi, was first described by Richard Lydekker in 1889 as Camptosaurus leedsi, the specific name honouring collector Alfred Nicholson Leeds. [2] Aside from Charles W. Gilmore suggesting in 1909 that it was probably more closely related to Dryosaurus than to Camptosaurus , [3] Camptosaurus leedsi attracted little attention for decades until it was reviewed by Peter Galton. First noting its distinctiveness in a review of English hypsilophodontids, [4] he then gave the species the new genus Callovosaurus in 1980, which he placed in Camptosauridae. [5] While considered a dubious iguanodontian in several reviews, which refer to it as "Camptosaurus" leedsi, [6] [7] Jose Ignacio Ruiz-Omeñaca and coauthors have proposed that Callovosaurus is a valid genus, and the oldest known dryosaurid. [1]

Palaeoecology

Callovosaurus was found in the lower Oxford Clay, which has yielded a diverse reptile assemblage: ichthyosaurs, plesiosaurs, crocodyliforms, pterosaurs, sauropod dinosaurs, the stegosaurids Loricatosaurus and Lexovisaurus , and the armoured dinosaur Sarcolestes . [1] [8] These rocks were once thought to be somewhat younger, from the Oxfordian of the Late Jurassic, but they are now known to be middle Callovian in age. [1]

The diet of Callovosaurus, like that of other iguanodontians, was plant material. It is one of the earliest known members of the iguanodontian lineage. [9]

Related Research Articles

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Valdosaurus is a genus of bipedal herbivorous iguanodont ornithopod dinosaur found on the Isle of Wight and elsewhere in England, Spain and possibly also Romania. It lived during the Early Cretaceous.

<span class="mw-page-title-main">Oxford Clay</span> Jurassic rock formation in southeast England

The Oxford Clay is a Jurassic marine sedimentary rock formation underlying much of southeast England, from as far west as Dorset and as far north as Yorkshire. The Oxford Clay Formation dates to the Jurassic, specifically, the Callovian and Oxfordian ages, and comprises two main facies. The lower facies comprises the Peterborough Member, a fossiliferous organic-rich mudstone. This facies and its rocks are commonly known as lower Oxford Clay. The upper facies comprises the middle Oxford Clay, the Stewartby Member, and the upper Oxford Clay, the Weymouth Member. The upper facies is a fossil poor assemblage of calcareous mudstones.

<i>Camptosaurus</i> Extinct genus of dinosaurs

Camptosaurus is a genus of plant-eating, beaked ornithischian dinosaurs of the Late Jurassic period of western North America and possibly also Europe. The name means 'flexible lizard'.

<span class="mw-page-title-main">Hypsilophodontidae</span> Extinct family of dinosaurs

Hypsilophodontidae is a traditionally used family of ornithopod dinosaurs, generally considered invalid today. It historically included many small bodied bipedal neornithischian taxa from around the world, and spanning from the Middle Jurassic until the Late Cretaceous. This inclusive status was supported by some phylogenetic analyses from the 1990s and mid 2000s, although there have also been many finding that the family is an unnatural grouping which should only include the type genus, Hypsilophodon, with the other genera being within clades like Thescelosauridae and Elasmaria. A 2014 analysis by Norman recovered a grouping of Hypsilophodon, Rhabdodontidae and Tenontosaurus, which he referred to as Hypsilophodontia. All other analyses from around the same time have instead found these latter taxa to be within Iguanodontia.

<i>Lexovisaurus</i> Extinct genus of reptiles

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<span class="mw-page-title-main">Dryosauridae</span> Extinct family of dinosaurs

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References

  1. 1 2 3 4 Ruiz-Omeñaca, José Ignacio; Pereda Suberbiola, Xabier; Galton, Peter M. (2007). "Callovosaurus leedsi, the earliest dryosaurid dinosaur (Ornithischia: Euornithopoda) from the Middle Jurassic of England". In Carpenter, Kenneth (ed.). Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs. Bloomington and Indianapolis: Indiana University Press. pp. 3–16. ISBN   978-0-253-34817-3.
  2. Lydekker, Richard (1889). "On the remains and affinities of five genera of Mesozoic reptiles". Quarterly Journal of the Geological Society of London. 45 (1–4): 41–59. doi:10.1144/GSL.JGS.1889.045.01-04.04. S2CID   128586645.
  3. Gilmore, Charles W. (1909). "Osteology of the Jurassic reptile Camptosaurus, with a revision of the genus, and description of two new species". Proceedings of the United States National Museum. 36 (1666): 197–332. doi:10.5479/si.00963801.36-1666.197.
  4. Galton, Peter M. (1975). "English hypsilophodontid dinosaurs (Reptilia:Ornithischia)" (PDF). Palaeontology. 18 (4): 741–752.
  5. Galton, Peter M. (1980). "European Jurassic ornithopod dinosaurs of the families Hypsilophodontidae and Camptosauridae". Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen. 160 (1): 73–95.
  6. Norman, David B.; Weishampel, David B. (1990). "Iguanodontidae and related ornithopods". In Weishampel, David B.; Dodson, Peter; Osmólska, Halszka (eds.). The Dinosauria. Berkeley: University of California Press. pp. 510–533. ISBN   0-520-06727-4.
  7. Norman, David B. (2004). "Basal Iguanodontia". In Weishampel, D.B.; Dodson, P.; Osmólska, H. (eds.). The Dinosauria (2nd ed.). Berkeley: University of California Press. pp. 413–437. ISBN   0-520-24209-2.
  8. Maidment, Susannah C.R.; Norman, David B.; Barrett, Paul M.; Upchurch, Paul (2008). "Systematics and phylogeny of Stegosauria (Dinosauria: Ornithischia)". Journal of Systematic Palaeontology. 6 (4): 367–407. doi:10.1017/S1477201908002459. S2CID   85673680.
  9. Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 142. ISBN   1-84028-152-9.