Callovosaurus
Encyclopedia
Callovosaurus is a genus
of iguanodont
ian 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
.
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 centimetre (0.918635170603675 ft) long, and is estimated to have belonged to an animal approximately 2.5 metres (8.2 ft) in length. A partial shin bone
from the same site or nearby, SMC
J.46889, may also belong to Callovosaurus.
The type species
, C. leedsi, was first described by Richard Lydekker
in 1889 as Camptosaurus
leedsi, the specific name honouring collector Alfred Nicholson Leeds. Aside from Charles W. Gilmore
suggesting in 1909 that it was probably more closely related to Dryosaurus
than to Camptosaurus
, Camptosaurus leedsi attracted little attention for decades until it was reviewed by Peter Galton
. First noting its distinctiveness in a review of English hypsilophodont
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.
s, plesiosaur
s, crocodyliforms
, pterosaur
s, sauropod
dinosaurs, the stegosaurids
Loricatosaurus
and the dubious Lexovisaurus
, and the armoured dinosaur
Sarcolestes
. 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.
The diet of Callovosaurus, like that of other iguanodontians, was plant material. It is one of the earliest known members of the iguanodontian lineage.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of iguanodont
Iguanodont
Iguanodonts were herbivorous dinosaurs that lived from the mid-Jurassic to Late Cretaceous. Some members include Camptosaurus, Callovosaurus, Iguanodon, Ouranosaurus, and the hadrosaurids or "duck-billed dinosaurs". Iguanodonts were one of the first groups of dinosaurs to be found...
ian dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
known from most of a left thigh bone
Femur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
discovered in Middle Jurassic
Middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from 176-161 million years ago. In European lithostratigraphy, rocks of this Middle Jurassic age are called the Dogger....
-age rocks of England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
. At times, it has been considered dubious
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
or a valid genus of basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
iguanodontian, perhaps a dryosaurid
Dryosauridae
Dryosaurids were primitive iguanodonts. They are known from Middle Jurassic to Early Cretaceous rocks of Africa, Europe, and North America.-Phylogeny:...
.
History and description
Callovosaurus is based onHolotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
BMNH
Natural History Museum
The Natural History Museum is one of three large museums on Exhibition Road, South Kensington, London, England . Its main frontage is on Cromwell Road...
R1993, a nearly complete left thigh bone. This specimen was collected from the middle Callovian
Callovian
In the geologic timescale, the Callovian is an age or stage in the Middle Jurassic, lasting between 164.7 ± 4.0 Ma and 161.2 ± 4.0 Ma. It is the last stage of the Middle Jurassic, following the Bathonian and preceding the Oxfordian....
–age (Middle Jurassic) Peterborough Member (former Lower Oxford Clay) of the Oxford Clay Formation
Oxford Clay
The 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 is of middle Callovian to lower Oxfordian age and comprises 2 main facies. The lower facies comprises the...
of Fletton, near Peterborough
Peterborough
Peterborough is a cathedral city and unitary authority area in the East of England, with an estimated population of in June 2007. For ceremonial purposes it is in the county of Cambridgeshire. Situated north of London, the city stands on the River Nene which flows into the North Sea...
in Cambridgeshire
Cambridgeshire
Cambridgeshire is a county in England, bordering Lincolnshire to the north, Norfolk to the northeast, Suffolk to the east, Essex and Hertfordshire to the south, and Bedfordshire and Northamptonshire to the west...
, England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
. The bone is 28 centimetre (0.918635170603675 ft) long, and is estimated to have belonged to an animal approximately 2.5 metres (8.2 ft) in length. A partial shin bone
Tibia
The tibia , shinbone, or shankbone is the larger and stronger of the two bones in the leg below the knee in vertebrates , and connects the knee with the ankle bones....
from the same site or nearby, SMC
Sedgwick Museum of Earth Sciences
The Sedgwick Museum of Earth Sciences, opened in 1904, is the geology museum of the University of Cambridge in England. It is part of the Department of Earth Sciences and is located on the University's Downing Site in Downing Street, central Cambridge, England.The Sedgwick has a collection of more...
J.46889, may also belong to Callovosaurus.
The type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
, C. leedsi, was first described by Richard Lydekker
Richard Lydekker
Richard Lydekker was an English naturalist, geologist and writer of numerous books on natural history.-Biography:...
in 1889 as Camptosaurus
Camptosaurus
Camptosaurus is a genus of plant-eating, beaked ornithischian dinosaurs of the Late Jurassic period of western North America. The name means 'flexible lizard', ....
leedsi, the specific name honouring collector Alfred Nicholson Leeds. Aside from Charles W. Gilmore
Charles W. Gilmore
Charles Whitney Gilmore was an American paleontologist, who named dinosaurs in North America and Mongolia, including the Cretaceous sauropod Alamosaurus, Alectrosaurus, Archaeornithomimus, Bactrosaurus, Brachyceratops, Chirostenotes, Mongolosaurus, Parrosaurus, Pinacosaurus, Styracosaurus and...
suggesting in 1909 that it was probably more closely related to Dryosaurus
Dryosaurus
Dryosaurus is a genus of an ornithopod dinosaur that lived in the Late Jurassic period. It was an iguanodont . Fossils have been found in the western United States, and were first discovered in the late 19th century...
than to Camptosaurus
Camptosaurus
Camptosaurus is a genus of plant-eating, beaked ornithischian dinosaurs of the Late Jurassic period of western North America. The name means 'flexible lizard', ....
, Camptosaurus leedsi attracted little attention for decades until it was reviewed by Peter Galton
Peter Galton
Peter M. Galton is a British vertebrate paleontologist working in America, who has to date written or co-written about a hundred papers in scientific journals or chapters in paleontology textbooks, especially on ornithischian and prosauropod dinosaurs.With Robert Bakker in a joint article...
. First noting its distinctiveness in a review of English hypsilophodont
Hypsilophodont
Hypsilophodonts were small ornithopod dinosaurs, regarded as fast, herbivorous bipeds on the order of 1–2 meters long . They are known from Asia, Australia, Europe, New Zealand, North America, and South America, from rocks of Middle Jurassic to late Cretaceous age...
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: ichthyosaurIchthyosaur
Ichthyosaurs were giant marine reptiles that resembled fish and dolphins...
s, plesiosaur
Plesiosaur
Plesiosauroidea is an extinct clade of carnivorous plesiosaur marine reptiles. Plesiosauroids, are known from the Jurassic and Cretaceous Periods...
s, crocodyliforms
Crocodyliformes
Crocodyliformes is a clade of crurotarsan archosaurs, the group often traditionally referred to as "crocodilians."In 1988, Michael J. Benton and James M. Clark argued that all traditional names for well-known groups of animals should be restricted to their crown clades, that is, used only for...
, pterosaur
Pterosaur
Pterosaurs were flying reptiles of the clade or order Pterosauria. They existed from the late Triassic to the end of the Cretaceous Period . Pterosaurs are the earliest vertebrates known to have evolved powered flight...
s, sauropod
Sauropoda
Sauropoda , or the sauropods , are an infraorder of saurischian dinosaurs. They had long necks, long tails, small heads , and thick, pillar-like legs. They are notable for the enormous sizes attained by some species, and the group includes the largest animals to have ever lived on land...
dinosaurs, the stegosaurids
Stegosauria
Known colloquially as stegosaurs, the Stegosauria are a group of herbivorous dinosaurs of the Jurassic and Early Cretaceous Periods, being found mostly in the Northern Hemisphere, predominantly in what is now North America and China....
Loricatosaurus
Loricatosaurus
Loricatosaurus is a genus of stegosaurid dinosaur from Callovian-age rocks of England and France...
and the dubious Lexovisaurus
Lexovisaurus
Lexovisaurus was one of the first dinosaurs from mid-to-Late Jurassic Europe, 164.7 mya to be discovered. It was a stegosaur. Its fossils have been found in France and northern England....
, and the armoured dinosaur
Ankylosauria
Ankylosauria is a group of herbivorous dinosaurs of the order Ornithischia. It includes the great majority of dinosaurs with armor in the form of bony osteoderms. Ankylosaurs were bulky quadrupeds, with short, powerful limbs. They are first known to have appeared in the early Jurassic Period of...
Sarcolestes
Sarcolestes
Sarcolestes is a genus of early ankylosaurian dinosaur from Middle Jurassic England, Callovian, around 163 million years ago. The type species, Sarcolestes leedsi, was described by Richard Lydekker in 1893, but is based on very fragmentary material, holotype BMNH R2682, consisting of a single left...
. These rocks were once thought to be somewhat younger, from the Oxfordian of the Late Jurassic
Late Jurassic
The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 161.2 ± 4.0 to 145.5 ± 4.0 million years ago , which is preserved in Upper Jurassic strata. In European lithostratigraphy, the name "Malm" indicates rocks of Late Jurassic age...
, 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.
External links
- Callovosaurus in the Dinosaur Encyclopaedia
- Callovosaurus in The Paleobiology Database