Concavenator

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Concavenator
Temporal range: Early Cretaceous,
~125  Ma
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Concavenator.jpg
Holotype specimen in articulation
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Family: Carcharodontosauridae
Genus: Concavenator
Ortega et al. 2010
Species:
C. corcovatus
Binomial name
Concavenator corcovatus
Ortega et al. 2010

Concavenator (meaning Cuenca hunter) is a genus of carcharodontosaurid dinosaur that lived in Spain during the Early Cretaceous epoch, about 125 million years ago. The genus contains a single species, Concavenator corcovatus named and described in 2010 from a nearly complete skeleton collected from Las Hoyas fossil site of La Huérguina Formation.

Contents

Concavenator was a medium-sized carcharodontosaurid, reaching about 5–6 m (16–20 ft) in length and 320–400 kg (710–880 lb) in weight. Unlike most carcharodontosaurids, the neural spines of the last dorsal (back) vertebrae were tall, creating a sail-like structure

History

The dig site in 2002 before excavation Concavenator digsite.jpg
The dig site in 2002 before excavation

The first fossil remains of Concavenator were recovered from limestone slabs of Las Hoyas locality (considered a Konservat-Lagerstätten ; deposits of exceptional fossil preservation) of Cuenca Province, Spain, which belongs to La Huérguina Formation. The remains were represented by an articulated, nearly complete skeleton of a theropod dinosaur individual encased in limestone, comprising the skull, ten cervical vertebrae, thirteen dorsal vertebrae (with the last two presenting an unusual elongation), five sacral vertebrae, thirty caudal vertebrae, a partial pectoral girdle and arm, the pelvic girdle and partial legs, as well as ribs. This specimen was also found preserving integument traces, such as scale impressions on the feet and tail, which is characteristic of many of the lithographic limestones within La Huérguina Formation. [1]

Fernando Escaso, Francisco Ortega, and Jose Luis Sanz examining the holotype of Concavenator Concavenator corcovatus.jpg
Fernando Escaso, Francisco Ortega, and José Luis Sanz examining the holotype of Concavenator

In 2010 the specimen was catalogued MCCM-LH 6666 and described by paleontologists Francisco Ortega, Fernando Escaso, and José Luis Sanz, used as the holotype for naming the new genus and species of carcharodontosaurid dinosaur Concavenator corcovatus. The specimen belongs to the collection of the Science Museum of Castilla-La Mancha. The generic name, Concavenator, is derived from the latin Conca, in reference to the region of discovery the Cuenca Province, and venator, which means hunter. The specific name, corcovatus, is taken from the latin corcovatus, giving glimpse onto the hump-like structure formed by the elongated dorsal vertebrae. In their description, the team noted that some anatomical elements had to be left unprepared (without removing the encasing rock) given the delicate nature of the preserved integument traces. [1] Though initially described in 2010, a series of monographs about the taxon and holotype were published later, including examinations to the feet integument in 2015, [2] as well as several anatomical redescriptions of the specimen in 2018. [3] [4] [5]

Description

Size

Size compared to a human Concavenator Scale.svg
Size compared to a human

Concavenator was a medium-sized carcharodontosaurid, reaching 5–6 m (16–20 ft) long and 320–400 kg (710–880 lb). [6] [7] [8] It possessed several unique features, including the two extremely tall vertebrae in front of the hips that formed a tall, narrow, pointed crest (possibly supporting a hump) on the dinosaur's back. [1] The function of such crests, however, is currently unknown. Paleontologist Roger Benson from the University of Cambridge 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. [9]

Integument

Conventional restoration of Concavenator with scales, a sail, and a small amount of quills Conca wikipedia.jpg
Conventional restoration of Concavenator with scales, a sail, and a small amount of quills

Concavenator had structures resembling quill knobs on its ulna, a feature known only in birds and other feathered theropods, such as dromaeosaurids. 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 have been thought to probably anchor 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 Concavenator and other allosauroids would be expected. [1] 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. [1]

Speculative restoration of Concavenator with a hump as a hypothetical thermoregulatory device Concavenator corcovatus thermo.jpg
Speculative restoration of Concavenator with a hump as a hypothetical thermoregulatory device

However, the significance of the 'quill knobs' remains controversial, as some amount of skepticism has been raised among experts on the validity of the interpretation that the ulnar bumps represent quill knobs. [10] Christian Foth and colleagues noted that the quill knobs of Concavenator were on the anterolateral side of the ulna. They suggest they were intermuscular lines that acted as tendon attachments. [11] The hypothesis that the bumps along the ulna represented muscular insertion points or ridges was subsequently examined and the results were presented at the 2015 meeting of the Society of Vertebrate Paleontology. Elena Cuesta Fidalgo, along with two of the researchers who initially described Concavenator (Ortega and Sanz), attempted to reconstruct its forearm musculature to determine if the ulnar bumps would be explained as an inter-muscular ridge. They identified the insertion point for the major arm muscles and determined that the row of bumps could not have been located between any of them. They found that the only possibility was that the bumps could be an attachment scar for the M. anconeus muscle. However, this is unlikely because this muscle normally attaches to a smooth surface without marks or bumps on the underlying bone. They argued that the most likely explanation for the bumps was their initial interpretation as feather quill knobs. The authors admitted that it was unusual for quill knobs to form along the posterolateral surface of the bone, but also noted that the same arrangement is found in some modern birds, like the Moorhen. [12]

Restoration of the holotype skull Concavenator Skull diagram.svg
Restoration of the holotype skull

In 2018, Cuesta Fidalgo published her doctorate thesis on the anatomy of Concavenator, which argued that the ulna was preserved in lateral view. This means that the ulnar bumps were positioned posterolaterally instead of anterolaterally as Cau and Mortimer claimed. Cuesta Fidalgo noted that the proximal part of the ulna is affected by fracturing and abrasion, with certain features that would have shifted when compared to their position in the bone while the animal was alive. For example, in the fossil, the lateral process of the ulna is positioned further posteriorly than the ulnar bumps. In Allosaurus and Acrocanthosaurus, the lateral process is on the lateral (rather than posterior) part of the bone, which would seem to support the ulnar bumps being anterolateral in position if the lateral process was truly preserved in lateral orientation in Concavenator. However, Cuesta Fidalgo described how the lateral process was distorted posteriorly when compared to the bumps and was not valid evidence for the claim that the ulna had shifted into anterior view. The ulna's distortion (as well as genus-specific proportions) means that precise comparisons to Allosaurus and Acrocanthosaurus would be misleading. [13] As Cuesta Fidalgo and her colleagues explained in 2015, the ulnar bumps could not be an intermuscular line if the bone is preserved in lateral view. [12] Cuesta Fidalgo and her colleagues pointed out that these bumps on the ulna are posterolateral, which is unlike that of interosseous ligaments. [3]

Classification

Mounted reconstructed skeleton Concavenator in Japan.jpg
Mounted reconstructed skeleton

The following cladogram after Novas et al., 2013, shows its place within Carcharodontosauria. [14]

Cau (2024) recovered Concavenator inside of a clade within Carcharodontosauridae, containing Sauroniops, Veterupristisaurus, Lusovenator, and Eocarcharia. [15]

Carcharodontosauridae
Neovenator
Neovenator.png

Carcharodontosaurus iguidensis (holotype maxilla)

Acrocanthosaurus
Acrocanthosaurus restoration.jpg

Eocarcharia (referred maxilla)

Meraxes
Meraxes gigas life restoration updated.png

Carcharodontosaurus iguidensis(referred cranial material)

Carcharodontosaurus saharicus (neotype)
Carcharodontosaurus.png

Carcharodontosaurus saharicus(described by Stromer in 1931)

See also

Related Research Articles

<i>Carcharodontosaurus</i> Genus of carcharodontosaurid dinosaur from the Cretaceous period

Carcharodontosaurus is a genus of carnivorous theropod dinosaur that lived in North Africa from about 100 to 94 million years ago during the Cenomanian age of the Late Cretaceous. Two teeth of the genus, now lost, were first described from Algeria by French paleontologists Charles Depéret and Justin Savornin as Megalosaurus saharicus. A partial skeleton was collected by crews of German paleontologist Ernst Stromer during a 1914 expedition to Egypt. Stromer did not report the Egyptian find until 1931, in which he dubbed the novel genus Carcharodontosaurus, making the type species C. saharicus. Unfortunately, this skeleton was destroyed during the Second World War. In 1995 a nearly complete skull of C. saharicus, the first well-preserved specimen to be found in almost a century, was discovered in the Kem Kem Beds of Morocco; it was designated the neotype in 1996. Fossils unearthed from the Echkar Formation of northern Niger were described and named as another species, C. iguidensis, in 2007.

<span class="mw-page-title-main">Carnosauria</span> Extinct group of theropod dinosaurs

Carnosauria is an extinct group of carnivorous theropod dinosaurs that lived during the Jurassic and Cretaceous periods.

<span class="mw-page-title-main">Ornithomimosauria</span> Extinct clade of theropod dinosaurs

Ornithomimosauria are theropod dinosaurs which bore a superficial resemblance to the modern-day ostrich. They were fast, omnivorous or herbivorous dinosaurs from the Cretaceous Period of Laurasia, as well as Africa and possibly Australia. The group first appeared in the Early Cretaceous and persisted until the Late Cretaceous. Primitive members of the group include Nqwebasaurus, Pelecanimimus, Shenzhousaurus, Hexing and Deinocheirus, the arms of which reached 2.4 m (8 feet) in length. More advanced species, members of the family Ornithomimidae, include Gallimimus, Struthiomimus, and Ornithomimus. Some paleontologists, like Paul Sereno, consider the enigmatic alvarezsaurids to be close relatives of the ornithomimosaurs and place them together in the superfamily Ornithomimoidea.

<i>Avimimus</i> Extinct genus of reptiles

Avimimus, meaning "bird mimic", is a genus of oviraptorosaurian theropod dinosaur, named for its bird-like characteristics, that lived in the late Cretaceous in what is now Mongolia, around 85 to 70 million years ago.

<i>Tyrannotitan</i> Carcharodontosaurid dinosaur genus from the early Cretaceous

Tyrannotitan is a genus of large bipedal carnivorous dinosaur of the carcharodontosaurid family from the Aptian stage of the early Cretaceous period, discovered in Argentina. It is closely related to other giant predators like Carcharodontosaurus and especially Giganotosaurus as well as Mapusaurus.

<span class="mw-page-title-main">Carcharodontosauridae</span> Extinct family of dinosaurs

Carcharodontosauridae is a group of carnivorous theropod dinosaurs. In 1931, Ernst Stromer named Carcharodontosauridae as a family, which, in modern paleontology, indicates a clade within Carnosauria. Carcharodontosaurids include some of the largest land predators ever known: Giganotosaurus, Mapusaurus, Carcharodontosaurus, and Tyrannotitan all rivaled Tyrannosaurus in size. Estimates give a maximum weight of 8–10 metric tons for the largest carcharodontosaurids, while the smallest carcharodontosaurids were estimated to have weighed at least 500 kilograms (1,100 lb).

<i>Pelecanimimus</i> Extinct genus of dinosaurs

Pelecanimimus is an extinct genus of basal ("primitive") ornithomimosaurian dinosaur from the Early Cretaceous of Spain. It is notable for possessing more teeth than any other member of the Ornithomimosauria, most of which were toothless.

<span class="mw-page-title-main">Compsognathidae</span> Extinct family of dinosaurs

Compsognathidae is a family of coelurosaurian theropod dinosaurs. Compsognathids were small carnivores, generally conservative in form, hailing from the Jurassic and Cretaceous Periods. The bird-like features of these species, along with other dinosaurs such as Archaeopteryx inspired the idea for the connection between dinosaur reptiles and modern-day avian species. Compsognathid fossils preserve diverse integument — skin impressions are known from four genera commonly placed in the group, Compsognathus, Sinosauropteryx, Sinocalliopteryx, and Juravenator. While the latter three show evidence of a covering of some of the earliest primitive feathers over much of the body, Juravenator and Compsognathus also show evidence of scales on the tail or hind legs. "Ubirajara jubatus", informally described in 2020, had elaborate integumentary structures on its back and shoulders superficially similar to the display feathers of a standardwing bird-of-paradise, and unlike any other non-avian dinosaur currently described.

<span class="mw-page-title-main">Velociraptorinae</span> Extinct subfamily of dinosaurs

Velociraptorinae is a subfamily of the theropod group Dromaeosauridae. Definitive fossils attributed to the subfamily have only been found in the Late Cretaceous deposits of East Asia, with Kansaignathus as the basalmost member, while numerous taxa from North America previously assigned to the velociraptorines are reclassified within Saurornitholestinae, Dromaeosaurinae or Eudromaeosauria outside these clades. Several teeth that may belong to indeterminate velociraptorines have also been discovered in Germany, dating to the Kimmeridgian stage of the Late Jurassic.

<span class="mw-page-title-main">Carnotaurinae</span> Extinct subfamily of reptiles

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<span class="mw-page-title-main">La Huérguina Formation</span> Geological formation in Spain

The La Huérguina Formation is a geological formation in Spain whose strata date back to the Barremian stage of the Early Cretaceous. Las Hoyas is a Konservat-Lagerstätte within the formation, located near the city of Cuenca, Spain. The site is mostly known for its exquisitely preserved dinosaurs, especially enantiornithines. The lithology of the formation mostly consists of lacustrine limestone deposited in a freshwater wetland environment.

<span class="mw-page-title-main">Megaraptora</span> Extinct clade of dinosaurs

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<i>Lajasvenator</i> Genus of carcharodontosaurid (fossil)

Lajasvenator is a genus of carcharodontosaurid dinosaur from the Mulichinco Formation from Neuquén Province in Argentina. The type and only species is Lajasvenator ascheriae. It was probably one of the smallest known allosauroids, being approximately only half the length of Concavenator, about 2.9 m (9.5 ft).

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<i>Lusovenator</i> Extinct genus of dinosaurs

Lusovenator is a genus of carcharodontosaurian theropod dinosaur, from the Late Jurassic (Kimmeridgian) Praia de Amoreira Porto-Novo Member and the Late Jurassic-Early Cretaceous (Tithonian-Berriasian) Assenta Member of the Lourinhã Formation in present-day Portugal. It includes one species, Lusovenator santosi.

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References

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