''Callovosaurus'' (meaning "

Callovian In the geologic timescale, the Callovian is an age and stage in the Middle Jurassic, lasting between 166.1 ± 4.0 Ma (million years ago) and 163.5 ± 4.0 Ma. It is the last stage of the Middle Jurassic, following the Bathonian and preceding the ...

lizard") is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

iguanodont Iguanodontia (the iguanodonts) is a clade of herbivorous dinosaurs that lived from the Middle Jurassic to Late Cretaceous. Some members include ''Camptosaurus'', ''Dryosaurus'', ''Iguanodon'', ''Tenontosaurus'', and the hadrosaurids or "duck-bi ...

ian

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

known from most of a left

thigh bone The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with t ...

discovered in

Middle Jurassic The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively rare, but geological formations ...

-age rocks of

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe ...

. At times, it has been considered

dubious Doubt is a mental state in which the mind remains suspended between two or more contradictory propositions, unable to be certain of any of them. Doubt on an emotional level is indecision between belief and disbelief. It may involve uncertainty ...

or a valid genus of

basal Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''. Science * Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure * Basal (medicine), a minimal level that is nec ...

iguanodontian, perhaps a dryosaurid.

History and description

''Callovosaurus'' is based on BMNH R1993, a nearly complete left thigh bone. This specimen was collected from the middle

–age (Middle Jurassic) Peterborough Member (former Lower Oxford Clay) of the

Oxford Clay Formation The Oxford Clay (or Oxford Clay Formation) 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, specifical ...

Fletton Fletton is an area of the city of Peterborough, in the City of Peterborough, Peterborough district, in the ceremonial county of Cambridgeshire, England, south of the River Nene. Notable for its large brickworks, the area has given its name to "F ...

, near

Peterborough Peterborough () is a cathedral city in Cambridgeshire, east of England. It is the largest part of the City of Peterborough unitary authority district (which covers a larger area than Peterborough itself). It was part of Northamptonshire until ...

Cambridgeshire Cambridgeshire (abbreviated Cambs.) is a Counties of England, county in the East of England, bordering Lincolnshire to the north, Norfolk to the north-east, Suffolk to the east, Essex and Hertfordshire to the south, and Bedfordshire and North ...

. The bone is long, and is estimated to have belonged to an animal approximately in length. A partial

shin bone The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...

from the same site or nearby, SMC J.46889, may also belong to ''Callovosaurus''. The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen( ...

, ''C. leedsi'', was first described by

Richard Lydekker Richard Lydekker (; 25 July 1849 – 16 April 1915) was an English naturalist, geologist and writer of numerous books on natural history. Biography Richard Lydekker was born at Tavistock Square in London. His father was Gerard Wolfe Lydekker ...

in 1889 as ''

Camptosaurus ''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' (Greek (') meaning 'bent' and (') meaning 'lizar ...

leedsi'', the specific name honouring collector

Alfred Nicholson Leeds Alfred Nicholson Leeds (9 March 184725 August 1917) was an English amateur palaeontologist. Biography Leeds was born at Eyebury, Peterborough, the youngest of the eight children of Edward Thurlow Leeds (180251) and Eliza Mary Leeds (née Nichol ...

. Aside from

Charles W. Gilmore Charles Whitney Gilmore (March 11, 1874 – September 27, 1945) was an American paleontologist who gained renown in the early 20th century for his work on vertebrate fossils during his career at the United States National Museum (now the ...

suggesting in 1909 that it was probably more closely related to ''

Dryosaurus ''Dryosaurus'' ( , meaning 'tree lizard', Greek ' () meaning 'tree, oak' and () meaning 'lizard'; the name reflects the forested habitat, not a vague oak-leaf shape of its cheek teeth as is sometimes assumed) is a genus of an ornithopod dinosaur ...

'' than to ''

'', ''Camptosaurus leedsi'' attracted little attention for decades until it was reviewed by

Peter Galton Peter Malcolm Galton (born 14 March 1942 in London) is a British vertebrate paleontologist who has to date written or co-written about 190 papers in scientific journals or chapters in paleontology textbooks, especially on ornithischian and prosau ...

. First noting its distinctiveness in a review of English

hypsilophodont Hypsilophodontidae (or Hypsilophodontia) 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 ...

ids, he then gave the species the new genus ''Callovosaurus'' in 1980, which he placed in Camptosauridae. While considered a dubious iguanodontian in several reviews, which refer to it as "Camptosaurus" ''leedsi'', Jose Ignacio Ruiz-Omeñaca and coauthors have proposed that ''Callovosaurus'' is a valid genus, and the oldest known dryosaurid.

Palaeoecology

''Callovosaurus'' was found in the lower Oxford Clay, which has yielded a diverse reptile assemblage:

ichthyosaur Ichthyosaurs (Ancient Greek for "fish lizard" – and ) are large extinct marine reptiles. Ichthyosaurs belong to the order known as Ichthyosauria or Ichthyopterygia ('fish flippers' – a designation introduced by Sir Richard Owen in 1842, altho ...

s, plesiosaurs,

crocodyliforms Crocodyliformes is a clade of crurotarsan archosaurs, the group often traditionally referred to as "crocodilians". They are the first members of Crocodylomorpha to possess many of the features that define later relatives. They are the only pseu ...

pterosaur Pterosaurs (; from Greek ''pteron'' and ''sauros'', meaning "wing lizard") is an extinct clade of flying reptiles in the Order (biology), order, Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cre ...

sauropod Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their ...

dinosaurs, the

stegosaurids Stegosauria is a group of Herbivore, herbivorous ornithischian dinosaurs that lived during the Jurassic and early Cretaceous Period (geology), periods. Stegosaurian fossils have been found mostly in the Northern Hemisphere, predominantly in what i ...

Loricatosaurus ''Loricatosaurus'' (meaning "armored lizard") is a Stegosaurid genus from Callovian-age (Middle Jurassic) rocks of England and France. Discovery and naming ''Loricatosaurus'' is known from remains previously assigned to ''Lexovisaurus'' that ...

'' and the dubious ''

Lexovisaurus ''Lexovisaurus'' is a genus of stegosaur from mid-to-Late Jurassic Europe, 165.7-164.7 mya. Fossils of limb bones and armor fragments have been found in middle to late Jurassic-aged strata of England. Discovery and taxonomy In the early ...

'', and the armoured dinosaur ''

Sarcolestes ''Sarcolestes'' (meaning "flesh robber") is an extinct genus of ankylosaurian ornithischian dinosaur from the Oxford Clay of England. The current type and only species is ''S. leedsi'', and the holotype is a single partial left mandible. The ...

''. These rocks were once thought to be somewhat younger, from the Oxfordian of the

Late Jurassic The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the ...

, but they are now known to be middle Callovian in age. The diet of ''Callovosaurus'', like that of other iguanodontians, was plant material. It is one of the earliest known members of the iguanodontian lineage.

References

External links

''Callovosaurus''
in

The Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals, plants, and microorganisms. History The Paleobiology Database (PBDB) originated in the NCEAS-funded Phanerozoic Marine Pale ...

{{Taxonbar, from=Q1579204 Iguanodonts Ornithischian genera Callovian genera Middle Jurassic dinosaurs of Europe Jurassic England Fossils of England Oxford Clay Fossil taxa described in 1980 Taxa named by Peter Galton