Concavenator
Encyclopedia
Concavenator is a genus
of theropod dinosaur
that lived approximately 130 million years ago during the early Cretaceous
period (Barremian
stage). The type species
is C. corcovatus; Concavenator corcovatus means "hump backed hunter from Cuenca
". The fossil was discovered in the Las Hoyas
fossil site of Spain
by paleontologists José Luis Sanz, Francisco Ortega and Fernando Escaso from the Autonomous University of Madrid and the National University of Distance Learning.
dinosaur possessing several unique features. Two extremely tall vertebrae in front of the hips formed a tall but narrow and pointed crest (possibly supporting a hump) on the dinosaur's back. The function of such crests is currently unknown. Paleontologist Roger Benson from Cambridge University speculated that one possibility is that "it is analogous to head-crests used in visual displays", but the Spanish scientists who discovered it noted it could also be a thermal regulator.
Additionally, the forelimb (ulna) of Concavenator preserved evidence of what may be quill knobs or homologous structures, an anatomical feature so far known only in animals with large, quilled feather
s on the forelimb.
. Quill knobs are created by ligaments which attach to the feather follicle, and since scales do not form from follicles, the authors ruled out the possibility that they could indicate the presence of long display scales on the arm. Instead, the knobs probably anchored simple, hollow, quill-like structures. Such structures are known both in coelurosaurs
such as Dilong
and in some ornithischians
like Tianyulong
and Psittacosaurus
. If the ornithischian quills are homologous with bird feathers, their presence in an allosauroid like Concavenator would be expected. However, if ornithischian quills are not related to feathers, the presence of these structures in Concavenator would show that feathers had begun to appear in earlier, more primitive forms than coelurosaurs. Feathers or related structures would then likely be present in the first members of the clade Neotetanurae, which lived in the Middle Jurassic
. No impressions of any kind of integument were found near the arm, although extensive scale impressions were preserved on other portions of the body, including broad, rectangular scales on the underside of the tail, bird-like scutes on the feet, and plantar pads on the undersides of the feet.
Some amount of skepticism exists among experts about the validity of the interpretation that the ulna bumps represent quill knobs, though a more detailed analysis has not yet been published. Darren Naish
of Tetrapod Zoology speculates that the bumps would have been unusually far up and irregularly spaced for quill knobs. He additionally pointed out that many animals have similar structures along intermuscular lines that act as tendon attachment points among other things.
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 theropod 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...
that lived approximately 130 million years ago during the early Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
period (Barremian
Barremian
The Barremian is an age in the geologic timescale between 130.0 ± 1.5 Ma and 125.0 ± 1.0 Ma). It is a subdivision of the Early Cretaceous epoch...
stage). 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...
is C. corcovatus; Concavenator corcovatus means "hump backed hunter from Cuenca
Cuenca (province)
Cuenca is a province of central Spain, in the eastern part of the autonomous community of Castile-La Mancha.-Guide to the area:Located in a natural setting of beauty, the Old Town of Cuenca occupies a superb site between two river gorges. Famous are its 15th Century "hanging houses" , that appear...
". The fossil was discovered in the Las Hoyas
Las Hoyas
Las Hoyas is a Cretaceous Konservat-Lagerstätten located near the city of Cuenca, Spain.It is dated as Barremian , and is mostly known from its exquisitely preserved dinosaurs, especially enantiornithines.- Taphonomy :...
fossil site of Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
by paleontologists José Luis Sanz, Francisco Ortega and Fernando Escaso from the Autonomous University of Madrid and the National University of Distance Learning.
Description
Concavenator was a medium-sized (roughly 6 meters (20 feet) long) primitive carcharodontosaurianCarcharodontosauridae
Carcharodontosaurids were a group of carnivorous theropod dinosaurs. In 1931 Ernst Stromer named Carcharodontosauridae as a family, in modern paleontology this name indicates a clade within Carnosauria...
dinosaur possessing several unique features. Two extremely tall vertebrae in front of the hips formed a tall but narrow and pointed crest (possibly supporting a hump) on the dinosaur's back. The function of such crests is currently unknown. Paleontologist Roger Benson from Cambridge University speculated that one possibility is that "it is analogous to head-crests used in visual displays", but the Spanish scientists who discovered it noted it could also be a thermal regulator.
Additionally, the forelimb (ulna) of Concavenator preserved evidence of what may be quill knobs or homologous structures, an anatomical feature so far known only in animals with large, quilled feather
Feather
Feathers are one of the epidermal growths that form the distinctive outer covering, or plumage, on birds and some non-avian theropod dinosaurs. They are considered the most complex integumentary structures found in vertebrates, and indeed a premier example of a complex evolutionary novelty. They...
s on the forelimb.
Feathers and scales
Concavenator had structures resembling quill knobs on its forearm, a feature known only in birds and other feathered theropods, such as VelociraptorVelociraptor
Velociraptor is a genus of dromaeosaurid theropod dinosaur that existed approximately 75 to 71 million years ago during the later part of the Cretaceous Period. Two species are currently recognized, although others have been assigned in the past. The type species is V. mongoliensis; fossils...
. Quill knobs are created by ligaments which attach to the feather follicle, and since scales do not form from follicles, the authors ruled out the possibility that they could indicate the presence of long display scales on the arm. Instead, the knobs probably anchored simple, hollow, quill-like structures. Such structures are known both in coelurosaurs
Coelurosauria
Coelurosauria is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs. In the past, it was used to refer to all small theropods, although this classification has been abolished...
such as Dilong
Dilong
Dilong Ward is one of the sixteen wards of Mokokchung town. It is located in the lower slope of the town and forms the Northern part of Mokokchung....
and in some ornithischians
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'...
like Tianyulong
Tianyulong
Tianyulong is a genus of heterodontosaurid ornithischian dinosaur. The only species is T. confuciusi, whose remains were discovered in Jianchang County, Western Liaoning Province, China...
and Psittacosaurus
Psittacosaurus
Psittacosaurus is a genus of psittacosaurid ceratopsian dinosaur from the Early Cretaceous Period of what is now Asia, about 130 to 100 million years ago. It is notable for being the most species-rich dinosaur genus...
. If the ornithischian quills are homologous with bird feathers, their presence in an allosauroid like Concavenator would be expected. However, if ornithischian quills are not related to feathers, the presence of these structures in Concavenator would show that feathers had begun to appear in earlier, more primitive forms than coelurosaurs. Feathers or related structures would then likely be present in the first members of the clade Neotetanurae, which lived in the 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....
. No impressions of any kind of integument were found near the arm, although extensive scale impressions were preserved on other portions of the body, including broad, rectangular scales on the underside of the tail, bird-like scutes on the feet, and plantar pads on the undersides of the feet.
Some amount of skepticism exists among experts about the validity of the interpretation that the ulna bumps represent quill knobs, though a more detailed analysis has not yet been published. Darren Naish
Darren Naish
Darren Naish is a vertebrate palaeontologist and science writer. He obtained a geology degree at the University of Southampton and later studied vertebrate palaeontology under British palaeontologist David Martill at the University of Portsmouth, where he obtained both an M. Phil...
of Tetrapod Zoology speculates that the bumps would have been unusually far up and irregularly spaced for quill knobs. He additionally pointed out that many animals have similar structures along intermuscular lines that act as tendon attachment points among other things.
