genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
pterosaur
Pterosaurs (; from Greek ''pteron'' and ''sauros'', meaning "wing lizard") is an extinct clade of flying reptiles in the order, Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 to ...
that lived during the
Early Cretaceous
The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma.
Geology
Pro ...
period, about 120 million years ago. The first fossil was discovered on the English
Isle of Wight
The Isle of Wight ( ) is a county in the English Channel, off the coast of Hampshire, from which it is separated by the Solent. It is the largest and second-most populous island of England. Referred to as 'The Island' by residents, the Isle of ...
in 1887, and in 1901 became the
holotype specimen
A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...
of a new species, ''O. latidens'' (Latin for "wide tooth"), in the genus ''
Ornithodesmus
''Ornithodesmus'' (meaning "bird link") is a genus of small, dromaeosaurid dinosaur from the Isle of Wight in England, dating to about 125 million years ago. The name was originally assigned to a bird-like sacrum (a series of vertebrae fused to ...
''. This species was moved to its own genus, ''Istiodactylus'', in 2001; this name is Greek for "sail finger". More specimens were described in 1913, and ''Istiodactylus'' was the only pterosaur known from three-dimensionally preserved fossils for much of the 20th century. In 2006, a species from China, ''I. sinensis'', was assigned to ''Istiodactylus'', but it has also been suggested to belong to a different genus.
''Istiodactylus'' was a large pterosaur; estimates of its wingspan range from . Its skull was about long, and was relatively short and broad for a pterosaur. The front of the snout was low and blunt, and bore a semicircle of 48 teeth. The triangular teeth were closely spaced, interlocked, and formed a "razor-edged" outline. The lower jaw also had a tooth-like projection that occluded with the teeth. The skull had a very large naso-antorbital opening (which combined the
antorbital fenestra
An antorbital fenestra (plural: fenestrae) is an opening in the skull that is in front of the eye sockets. This skull character is largely associated with archosauriforms, first appearing during the Triassic Period. Among extant archosaurs, birds ...
and the opening for the bony nostril) and a slender eye socket. Some of the
vertebra
The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...
e were fused into a
notarium
Notarium or os dorsale is a bone consisting of the fused vertebra of the shoulder in birds and some pterosaurs. The structure helps brace the chest against the forces generated by the wings. In birds, the vertebrae are only in contact with adjac ...
, to which the shoulder blades connected. It had very large forelimbs, with a wing-membrane distended by a long wing-finger, but the
hindlimb
A hindlimb or back limb is one of the paired articulated appendages (limbs) attached on the caudal ( posterior) end of a terrestrial tetrapod vertebrate's torso.http://www.merriam-webster.com/medical/hind%20limb, Merriam Webster Dictionary-Hindl ...
s were very short.
Until the 21st century, ''Istiodactylus'' was the only known pterosaur of its kind, and was placed in its own
family
Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
,
Istiodactylidae
Istiodactylidae is a small family of pterosaurs. This family was named in 2001 after the type genus ''Istiodactylus'' was discovered not to be a member of the genus ''Ornithodesmus''.
Systematics and distribution
Remains of taxa that can be co ...
, within the group
Ornithocheiroidea
Ornithocheiroidea (or ornithocheiroids) is a group of pterosaurs within the extinct suborder Pterodactyloidea. They were typically large pterosaurs that lived from the Early to Late Cretaceous periods (Valanginian to Maastrichtian stages), with f ...
. ''Istiodactylus'' differed from other istiodactylids in having a proportionally shorter skull. The distinctive teeth of ''Istiodactylus'' indicate that it was a
scavenger
Scavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a herbivorous feeding b ...
that may have used its teeth to sever morsels from large carcasses in the manner of a
cookie cutter
A cookie cutter in North American English, also known as a biscuit cutter outside North America, is a tool to cut out cookie/biscuit dough in a particular shape.
They are often used for seasonal occasions when well-known decorative shapes are ...
. The wings of ''Istiodactylus'' may have been adapted for soaring, which would have helped it find carcasses before
terrestrial
Terrestrial refers to things related to land or the planet Earth.
Terrestrial may also refer to:
* Terrestrial animal, an animal that lives on land opposed to living in water, or sometimes an animal that lives on or near the ground, as opposed to ...
carnivore
A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other sof ...
s. ''Istiodactylus'' is known from the
Wessex Formation
The Wessex Formation is a fossil-rich English geological formation that dates from the Berriasian to Barremian stages (about 145–125 million years ago) of the Early Cretaceous. It forms part of the Wealden Group and underlies the younger Vecti ...
and the younger
Vectis Formation
The Vectis Formation is a geological formation on the Isle of Wight and Swanage, England whose strata were formed in the lowermost Aptian, approximately 125 million years ago."Magnetostratigraphy of the Lower Cretaceous Vectis Formation (Wealden ...
, which represent river and coastal environments that were shared with various pterosaurs,
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 ...
s, and other animals.
History of discovery
In 1887, the British
palaeontologist
Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...
synsacrum
The synsacrum is a skeletal structure of birds and other dinosaurs, in which the sacrum is extended by incorporation of additional fused or partially fused caudal or lumbar vertebrae and it can only be seen in birds. Some posterior thoracic vert ...
(fused vertebrae attached to the pelvis) from the
Wessex Formation
The Wessex Formation is a fossil-rich English geological formation that dates from the Berriasian to Barremian stages (about 145–125 million years ago) of the Early Cretaceous. It forms part of the Wealden Group and underlies the younger Vecti ...
of the
Isle of Wight
The Isle of Wight ( ) is a county in the English Channel, off the coast of Hampshire, from which it is separated by the Solent. It is the largest and second-most populous island of England. Referred to as 'The Island' by residents, the Isle of ...
, an island off the coast of southern England. Though he compared it with those of
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 ...
s and
pterosaurs
Pterosaurs (; from Greek ''pteron'' and ''sauros'', meaning "wing lizard") is an extinct clade of flying reptiles in the order, Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 to ...
, he concluded that it belonged to a bird (though more dinosaur-like than any known bird), which he named '' Ornithodesmus cluniculus''. The British
geologist
A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes Earth and other terrestrial planets, as well as the processes that shape them. Geologists usually study geology, earth science, or geophysics, althou ...
John W. Hulke suggested later that year that ''Ornithodesmus'' was a pterosaur, finding it similar to fossils that he had seen before, but Seeley disagreed. In his 1901 ''Dragons of the Air'', the first popular book about pterosaurs, Seeley reported another specimen (NHMUK R176 at the
Natural History Museum
A natural history museum or museum of natural history is a scientific institution with natural history collections that include current and historical records of animals, plants, fungi, ecosystems, geology, paleontology, climatology, and more. ...
in London, formerly BMNH), found by
the Reverend
The Reverend is an style (manner of address), honorific style most often placed before the names of Christian clergy and Minister of religion, ministers. There are sometimes differences in the way the style is used in different countries and c ...
British Museum
The British Museum is a public museum dedicated to human history, art and culture located in the Bloomsbury area of London. Its permanent collection of eight million works is among the largest and most comprehensive in existence. It docum ...
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 1888, but Seeley considered it another species of the genus ''Ornithodesmus'', which he now considered pterosaurian. Seeley named the new species ''O. latidens''; ''latus'' is Latin for "wide" and ''dens'' means "tooth", a name originally used by Fox and his friends. Seeley presumably assigned the new species to the existing genus due to similarities between their sacra, but with little explanation.
Specimen NHMUK R176 is a poorly preserved skeleton consisting of the back of the skull, a neck vertebra, the sternum, the sacrum, the right humerus, the notarium, the left humerus, part of the
radius
In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...
and ulna, carpals, metacarpals, and wing
phalanx bone
The phalanges (singular: ''phalanx'' ) are digital bones in the hands and feet of most vertebrates. In primates, the thumbs and big toes have two phalanges while the other digits have three phalanges. The phalanges are classed as long bones.
...
s. Though Seeley did not designate a
holotype specimen
A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...
for ''O. latidens'', he described and illustrated parts of NHMUK R176, which makes the 1901 naming valid according to the
International Commission on Zoological Nomenclature
The International Commission on Zoological Nomenclature (ICZN) is an organization dedicated to "achieving stability and sense in the scientific naming of animals". Founded in 1895, it currently comprises 26 commissioners from 20 countries.
Orga ...
, and the specimen is considered the holotype today. Later researchers have been mystified by the fact that Seeley described the jaws and teeth of ''O. latidens'' and named it after the latter, when the only specimen available in 1901, NHMUK R176, does not appear to have had these elements. Only the back of the skull was listed as present by Lydekker in 1888, but it was rumoured that a set of jaws had been lost from Fox's collection, so it is possible that Seeley had examined them prior to this.
In 1913, the British amateur palaeontologist Reginald W. Hooley described two more specimens of ''O. latidens'', collected from the sea after a
rockfall
A rockfall or rock-fallWhittow, John (1984). ''Dictionary of Physical Geography''. London: Penguin, 1984. . is a quantity/sheets of rock that has fallen freely from a cliff face. The term is also used for collapse of rock from roof or walls of min ...
near Atherfield Point on the Isle of Wight in 1904, originating from the
Vectis Formation
The Vectis Formation is a geological formation on the Isle of Wight and Swanage, England whose strata were formed in the lowermost Aptian, approximately 125 million years ago."Magnetostratigraphy of the Lower Cretaceous Vectis Formation (Wealden ...
. The first of these, NHMUK R3877, was collected as three blocks and consists of a skull, neck and trunk vertebrae, a shoulder blade, an
, and parts of the forelimbs. The second specimen, NHMUK R3878, was collected in one block, and includes parts of the
pectoral girdle
The shoulder girdle or pectoral girdle is the set of bones in the appendicular skeleton which connects to the arm on each side. In humans it consists of the clavicle and scapula; in those species with three bones in the shoulder, it consists of t ...
and forelimbs. These specimens represent the most complete remains of
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...
pterosaurs found in England, and NHMUK R3877 was one of the only known three-dimensionally preserved pterosaur skeletons for much of the 20th century (pterosaur bones are often flattened
compression fossil
A compression fossil is a fossil preserved in sedimentary rock that has undergone physical compression. While it is uncommon to find animals preserved as good compression fossils, it is very common to find plants preserved this way. The reason fo ...
s). Hooley discussed ''O. latidens'' in detail, and placed the genus ''Ornithodesmus'' in its own family, Ornithodesmidae. His article ended with a discussion wherein it was noted that the palaeontologist
Charles William Andrews
Charles William Andrews (30 October 1866 – 25 May 1924) F.R.S., was a British palaeontologist whose career as a vertebrate paleontologist, both as a curator and in the field, was spent in the services of the British Museum, Department of Ge ...
had expressed doubts as to whether ''O. latidens'' belonged in the genus ''Ornithodesmus'', as the vertebrae of the specimen that genus was based on differed markedly from those of Hooley's specimen. The American palaeontologist Samuel W. Williston subsequently reviewed Hooley's article, disagreeing with some of his conclusions about the anatomy and classification of the animal. After Hooley's
monograph
A monograph is a specialist work of writing (in contrast to reference works) or exhibition on a single subject or an aspect of a subject, often by a single author or artist, and usually on a scholarly subject.
In library cataloging, ''monograph ...
, little was written about the animal for the rest of the 20th century, and no similar pterosaurs were found for decades.
New genus and assigned species
In 1993, the British palaeontologists Stafford C. Howse and Andrew C. Milner concluded that the holotype sacrum and only specimen of ''O. cluniculus'' did not belong to a pterosaur, but to a
maniraptora
Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and the non-avian dinosaurs that were more closely related to them than to ''Ornithomimus velox''. It contains the major subgroups Avialae, Deinonychosauria, Oviraptoros ...
n dinosaur (this conclusion had also been reached independently by the British palaeontologist Christopher Bennett). They pointed out that no detailed attempts had been made to compare the sacrum of ''O. cluniculus'' with those of pterosaurs, and that ''O. latidens'' had in effect been treated as 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 ...
of the genus ''Ornithodesmus'', with one writer even treating the original species as a synonym of the newer. As a definite species of pterosaurs, "''O.''" ''latidens'' therefore required a new genus name. In 2001, Howse, Milner, and