Thecospondylus
Encyclopedia
Thecospondylus is a dubious
genus
of dinosaur
from the Early Cretaceous
of England
Dr. A.C. Horner, an amateur geologist living at Tonbridge
, in the nineteenth century acquired a fossil found in the quarry of Southborough
. He sent it to paleontologist Harry Govier Seeley who in 1882 described and named it as the type species
Thecospondylus Horneri. The genus name is derived from Greek
theke meaning 'sheath' and spondylos meaning 'vertebra', a reference to the "extremely thin" bone forming the vertebrae. The specific name honours Horner.
The holotype
, BMNH R.291, was found in a layer of the Hastings Sand, sandstone
dating from the Valanginian
- Hauterivian
. It consist of an elongated natural internal cast or endocast
of the neural canal of the sacrum
, about sixty centimetres long. It shows the divisions of at least five and probably seven sacral vertebrae. On three of them the cancellous bone is still present to which the generic name is referring. It is the only known fossil that can be definitely assigned to this genus.
A second species, T. daviesi, was added by Seeley in 1888, but later given its own genus, Thecocoelurus
. In 1926 Friedrich von Huene
renamed T. horneri to Thecocoelurus horneri, but this has not been commonly accepted, because Thecospondylus would have priority.
Based on such meagre material, the affinities of T. horneri have been hard to determine. Seeley himself merely assigned it to Dinosauria. Richard Lydekker
in 1888 referred it to the Sauropoda
. Von Huene however in 1909 considered it to be a member of the theropod family Coeluridae
. Recent authors conclude it is a nomen dubium
, of which it is not even certain whether it is a saurischia
n or a ornithischia
n.
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
genus
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 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...
from the Early Cretaceous
Early Cretaceous
The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...
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...
Dr. A.C. Horner, an amateur geologist living at Tonbridge
Tonbridge
Tonbridge is a market town in the English county of Kent, with a population of 30,340 in 2007. It is located on the River Medway, approximately 4 miles north of Tunbridge Wells, 12 miles south west of Maidstone and 29 miles south east of London...
, in the nineteenth century acquired a fossil found in the quarry of Southborough
Southborough
Southborough is the name of several places:* Southborough, Bromley in London, England* Southborough, Kingston upon Thames in London, England* Southborough, Kent in England* Southborough, Massachusetts in the USA** Southborough...
. He sent it to paleontologist Harry Govier Seeley who in 1882 described and named it as 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...
Thecospondylus Horneri. The genus name is derived from Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
theke meaning 'sheath' and spondylos meaning 'vertebra', a reference to the "extremely thin" bone forming the vertebrae. The specific name honours Horner.
The holotype
Holotype
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 R.291, was found in a layer of the Hastings Sand, sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
dating from the Valanginian
Valanginian
In the geologic timescale, the Valanginian is an age or stage of the Early or Lower Cretaceous. It spans between 140.2 ± 3.0 Ma and 136.4 ± 2.0 Ma...
- Hauterivian
Hauterivian
The Hauterivian is, in the geologic timescale, an age in the Early Cretaceous epoch or a stage in the Lower Cretaceous series. It spans the time between 136.4 ± 2 Ma and 130 ± 1.5 Ma...
. It consist of an elongated natural internal cast or endocast
Endocast
An endocast is the internal cast of a hollow object, often specifically used for an endocasts of the cranial vault. Endocasts can be man-made for examining the properties of a hollow, inaccessible space, or occur naturally through fossilisation....
of the neural canal of the sacrum
Sacrum
In vertebrate anatomy the sacrum is a large, triangular bone at the base of the spine and at the upper and back part of the pelvic cavity, where it is inserted like a wedge between the two hip bones. Its upper part connects with the last lumbar vertebra, and bottom part with the coccyx...
, about sixty centimetres long. It shows the divisions of at least five and probably seven sacral vertebrae. On three of them the cancellous bone is still present to which the generic name is referring. It is the only known fossil that can be definitely assigned to this genus.
A second species, T. daviesi, was added by Seeley in 1888, but later given its own genus, Thecocoelurus
Thecocoelurus
Thecocoelurus is a genus of theropod dinosaur from the early Cretaceous period of England.Thecocoelurus is known only from half of a single cervical vertebra, discovered by the Rev. William Darwin Fox on the Isle of Wight during the 19th century. After his death the Fox Collection was acquired by...
. In 1926 Friedrich von Huene
Friedrich von Huene
Friedrich von Huene was a German paleontologist who named more dinosaurs in the early 20th century than anyone else in Europe.-Biography:...
renamed T. horneri to Thecocoelurus horneri, but this has not been commonly accepted, because Thecospondylus would have priority.
Based on such meagre material, the affinities of T. horneri have been hard to determine. Seeley himself merely assigned it to Dinosauria. Richard Lydekker
Richard Lydekker
Richard Lydekker was an English naturalist, geologist and writer of numerous books on natural history.-Biography:...
in 1888 referred it to the Sauropoda
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...
. Von Huene however in 1909 considered it to be a member of the theropod family Coeluridae
Coeluridae
Coeluridae is a historically polyphyletic family of generally small, carnivorous dinosaurs from the late Jurassic Period...
. Recent authors conclude it is a nomen dubium
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
, of which it is not even certain whether it is a saurischia
Saurischia
Saurischia meaning 'lizard' and ischion meaning 'hip joint') is one of the two orders, or basic divisions, of dinosaurs. In 1888, Harry Seeley classified dinosaurs into two orders, based on their hip structure...
n or a ornithischia
Ornithischia
Ornithischia or Predentata is an extinct order of beaked, herbivorous dinosaurs. The name ornithischia is derived from the Greek ornitheos meaning 'of a bird' and ischion meaning 'hip joint'...
n.