Neovenator

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Neovenator
Temporal range: Hauterivian-Barremian
~130–125  Ma
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Neovenator.jpg
Reconstructed skeleton in Japan
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Clade:† Allosauria
Clade:† Carcharodontosauria
Family:† Neovenatoridae
Genus:† Neovenator
Hutt, Martill & Barker, 1996
Species:
†N. salerii
Binomial name
†Neovenator salerii
Hutt, Martill & Barker, 1996

Neovenator (nee-o-ven-a-tor meaning "new hunter") is a genus of carcharodontosaurian theropod dinosaur. It is known from several skeletons found in the Early Cretaceous (Hauterivian-Barremian) Wessex Formation on the south coast of the Isle of Wight, southern England. It is one of the best known theropod dinosaurs from the Early Cretaceous of Europe.

Contents

Discovery and species

Mounted skeleton and fossils, Dinosaur Isle Neovenator salerii-Dinosaurisle.jpg
Mounted skeleton and fossils, Dinosaur Isle

The first bones of Neovenator were discovered in the summer of 1978, when a storm made part of the Grange Chine collapse. Rocks containing fossils fell to the beach of Brighstone Bay on the southwestern coast of the Isle of Wight. The rocks consisted of plant debris bed L9 within the variegated clays and marls of the Wessex Formation dating from the Barremian stage of the Early Cretaceous, about 125 million years ago. They were first collected by the Henwood family and shortly afterwards by geology student David Richards. Richards sent the remains to the Museum of Isle of Wight (now Dinosaur Isle) and the British Museum of Natural History. In the latter institution paleontologist Alan Jack Charig determined that the bones belonged to two kinds of animal: Iguanodon and a theropod. The "Iguanodon", later referred to Mantellisaurus and ultimately made the separate genus Brighstoneus , generated the most interest and in the early 1980s a team was sent by the BMNH to secure more of its bones. On that occasion an additional theropod tail vertebra was discovered.

Several amateur paleontologists, among them Keith and Jenny Simmonds, now began to search for additional remains of the predator. Ultimately, the total of secured bones included the snout, teeth, a front lower jaw, most of the vertebral column, ribs, belly ribs, chevrons, the left shoulder girdle, pelvis bones and a hindlimb. These were accessioned under numbers BMNH R10001 and MIWG 6348. They equalled approximately 70% of the skeleton. In 1985, excavations undertaken by Steve Hutt of the MIWG revealed two vertebrae of a second individual, specimen MIWG.5470. In 1987, Jenny Simmonds found a third skeleton, containing vertebra and pelvic bones, specimen MIWG.6352. A fourth individual found by Nick Oliver is represented by specimen IWCMS 2002.186, [1] consisting of a lower jaw, parts of the cervical vertebrae and limb elements. In 1990 the material, then considered a possible new species of Megalosaurus , was provisionally described by Hutt. Having mistaken the ischium of MIWG 6352 for a pubic bone, Hutt suggested this specimen represented a separate species. [2]

Reconstructed skull in anterior (left) and left lateral (right) views Neovenator skull reconstruction.png
Reconstructed skull in anterior (left) and left lateral (right) views

In 1996, Steve Hutt, David Martill and Michael Barker named and described the type species Neovenator salerii. The generic name Neovenator means "new hunter" from the Greek neo~, "new" and Latin venator, "hunter". The specific name salerii honours the land owners of the site, the Salero family. In view of the large number of individuals involved in the discovery process, it was considered improper to single out one of them as discoverer. The holotype is the skeleton accessioned as BMNH R10001 and MIWG 6348. [3]

In 1999, Hutt dedicated his (unpublished) master thesis to Neovenator. [4]

In 2008, Stephen Louis Brusatte, Roger Benson and Hutt redescribed the species in great detail. [5]

In 2012, teeth indistinguishable from those of the holotype of Neovenator were found in the Angeac lignitic bone bed, France, dating to the Barremian. [6]

Description

Restoration Neovenator.png
Restoration

Neovenator measured approximately 7 metres (23 ft) in length, and was of a gracile build, weighing 1 metric ton (1.1 short tons). [7] Specimen MIWG 4199 indicates an individual with a possible length of about 10 metres (33 ft), but it only consists of a toe phalanx and its position in Neovenator is dubious. [8] [9]

The various scientific descriptions of Neovenator have indicated some distinguishing traits. The nostril is twice as long as it is high. The praemaxilla in the snout bears five teeth. The maxilla is pierced by a large maxillary fenestra, the diameter of which equals a sixth of the length of the tooth row. The tooth crown equals a quarter of the tooth length, thus including the root. The toe claws have a groove on top. [3] Both praemaxillae are connected by an extra pen-in-socket connection. [10] The front joint surface of the intercentrum of the axis, the second neck vertebra, is transversely widened. The odontoid process of the axis has small openings along the side edge of the front facet. The neural process of the axis has a single small opening in the side. The rear neck vertebrae are fused with their neck ribs. On the eighth and ninth neck vertebrae, at the parapophysis, the lower rib joint facet, the internal camellate structure of the bone is visible. At the front neck vertebrae the undersides are formed as sharp keels which are not inset from the lateral sides. At the front back vertebrae, the hypapophyses, the lower swellings of the front facet edges, are formed like low mounds. On the rear back vertebrae the facets of the joint processes are continued sideways as curved flanges. The shoulder joint is wider transversely than long, measured from the front to the rear. The notch on the underside of the front blade of the ilium has a shelf at the inner side. The ilium in Neovenator is highly pneumatized [11] . The "feet" of the ischia are connected at their fronts but diverge at their rears. The head of the thighbone is obliquely directed to the front, to above and to the inside. On the thighbone the lesser trochanter has a robust ridge on its outer side. On the thighbone the fourth trochanter has a depression in the form of a thumbprint located to the outside of its upper limit. The front underside of the thighbone is nearly flat, only showing a short vertical groove between the lower condyles. The lower shinbone shows an oval rough area at the inner side. The top of the outer malleolus of the shinbone is pinched from the front to the rear. The outer front bulge of the top surface of the shinbone has a spur pointing to below. In the foot, the outer side of the second metatarsal has a hollow surface to contact the third metatarsal. [5]

Estimated size based on the holotype Neovenator Scale.png
Estimated size based on the holotype

Several traits that once were thought to be unique or apomorphic for Neovenator, subsequent research showed to have been shared by other theropods. The nostrils are large but not uncommonly so. Having pneumatised rear back vertebrae is normal for carcharodontosaurids. Elevated paired nasal crests are shared with Allosaurus. Denticles continuing over the tooth apex are today known from other species. [5]

In 2015, it was reported that the front of the snout of Neovenator contains a complex system of neurovascular canals, functioning as sensory organs. This trait is also known from Spinosauridae and was there explained as an adaptation for searching prey in water. It was doubted, however, whether Neovenator used its system for the same purpose. [12]

Classification

At the time that it was described, by Steve Hutt, Martill and Barker in 1996, it was considered the only known allosaurid in Europe. However, further studies suggested it had more in common with the advanced carcharodontosaurid group of allosaurs, and several studies including a detailed examination of the species by Benson, Carrano and Brusatte in 2010 suggest that it is closely related to the Carcharodontosauridae (in a group called Carcharodontosauria), but is actually closer to the megaraptorans, together with them forming the family Neovenatoridae. [11] Other studies have supported Neovenator being a carcharodontosaurid, and megaraptorans being tyrannosauroids.

First back vertebra Neovenator salerii dorsal vertebra.jpg
First back vertebra
Reconstructed skeleton, World Museum Liverpool Megalosaurus, World Museum Liverpool (2).JPG
Reconstructed skeleton, World Museum Liverpool

The cladogram below follows the 2010 analysis by Benson, Carrano and Brusatte. [11]

Neovenatoridae

Cladogram after Novas et al., 2013 [13]

Palaeobiology

Senses

Praemaxilla and maxilla, with neurovascular network and CT sections Premaxilla and maxilla of Neovenator.jpg
Praemaxilla and maxilla, with neurovascular network and CT sections

Chris Barker and colleagues suggested that Neovenator may have possessed integumentary sensory organs on its snout, much as modern waterfowl and crocodilians use to find food in muddy water, based on neurovascular structures found on the skull. As Neovenator is believed to be completely terrestrial, unlike the modern species, it is assumed that these sensory organs were used for other purposes, such as sensitivity to pressure and temperature, controlling jaw pressure and precision feeding. In support of this, the tooth wear for Neovenator seems to indicate that it avoided eating or biting into bone while it fed. Additionally, Neovenator might have used these integumentary sensory organs in courtship and sensing nest conditions, a technique seen today in most species of crocodilians and megapode birds. Though such structures are known for another theropod, the tyrannosaurid Daspletosaurus horneri , Neovenator's neurovascular structures that likely supported these organs are the best preserved and most complete in any known theropod yet discovered. [14] [15] However, a more recent study reviewing the evolution of the trigeminal canals among sauropsids notes that a much denser network of neurovascular canals in the snout and lower jaw is more commonly encountered in aquatic or semiaquatic taxa (e.g., Spinosaurus , Halszkaraptor , Plesiosaurus ), and taxa that developed a rhamphotheca (e.g., Caenagnathasia ), while terrestrial taxa such as tyrannosaurids and Neovenator may have had average facial sensitivity for non-edentulous terrestrial theropods, although further research is needed. [16]

Palaeopathology

The holotype of Neovenator salerii had many pathologies. The authors of the genus list them as "midcaudal vertebrae fusions, healed fractures of mid-caudal vertebra transverse processes; osteophytes affecting pedal phalanges, healed gastralia rib fractures, some forming false joints... [and] scapula fracture." [17]

Palaeoecology

Fossil remains of Neovenator have been found on the Isle of Wight off southern England, and were first discovered in the 20th century. Neovenator perhaps existed alongside other dinosaurs found in the Wessex Formation of the early Cretaceous period, such as Ceratosuchops, Riparovenator, Baryonyx , Polacanthus , Iguanodon and Eotyrannus . The holotype bones were mixed with those of the herbivorous iguanodontian Brighstoneus and in the dig site also remains of fishes, amphibians, lizards, pterosaurs and Goniopholididae were present. Neovenator was likely the apex predator of its ecosystem.

Related Research Articles

<span class="mw-page-title-main">Dinosaur Isle</span> Dinosaur museum on the Isle of Wight

Dinosaur Isle is a purpose-built dinosaur museum located in Sandown on the Isle of Wight in southern England.

<i>Baryonyx</i> Genus of theropod dinosaurs

Baryonyx is a genus of theropod dinosaur which lived in the Barremian stage of the Early Cretaceous period, about 130–125 million years ago. The first skeleton was discovered in 1983 in the Smokejack Clay Pit, of Surrey, England, in sediments of the Weald Clay Formation, and became the holotype specimen of Baryonyx walkeri, named by palaeontologists Alan J. Charig and Angela C. Milner in 1986. The generic name, Baryonyx, means "heavy claw" and alludes to the animal's very large claw on the first finger; the specific name, walkeri, refers to its discoverer, amateur fossil collector William J. Walker. The holotype specimen is one of the most complete theropod skeletons from the UK, and its discovery attracted media attention. Specimens later discovered in other parts of the United Kingdom and Iberia have also been assigned to the genus, though many have since been moved to new genera.

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

Suchomimus is a genus of spinosaur dinosaur that lived between 125 and 112 million years ago in what is now Niger, north Africa, during the Aptian to early Albian stages of the Early Cretaceous period. It was named and described by paleontologist Paul Sereno and colleagues in 1998, based on a partial skeleton from the Elrhaz Formation. Suchomimus's long and shallow skull, similar to that of a crocodile, earns it its generic name, while the specific name Suchomimus tenerensis alludes to the locality of its first remains, the Ténéré Dese.

The Isle of Wight is one of the richest dinosaur localities in Europe, with over 20 species of dinosaur having been recognised from the early Cretaceous Period, some of which were first identified on the island, as well as the contemporary non-dinosaurian species of crocodile, turtle and pterosaur.

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

Valdosaurus is a genus of bipedal herbivorous iguanodont ornithopod dinosaur found on the Isle of Wight and elsewhere in England, Spain and possibly also Romania. It lived during the Early Cretaceous.

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

Eotyrannus is a genus of tyrannosauroid theropod dinosaur hailing from the Early Cretaceous Wessex Formation beds, included in Wealden Group, located in the southwest coast of the Isle of Wight, United Kingdom. The remains (MIWG1997.550), consisting of assorted skull, axial skeleton and appendicular skeleton elements, from a juvenile or subadult, found in a plant debris clay bed, were described by Hutt et al. in early 2001. The etymology of the generic name refers to the animal's classification as an early tyrannosaur or "tyrant lizard", while the specific name honors the discoverer of the fossil.

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

Aristosuchus is a genus of small coelurosaurian dinosaur whose name was derived from the Greek ἄριστος and σουχος. It shared many characteristics with birds.

Calamospondylus is a genus of theropod dinosaur. It lived during the Early Cretaceous and its fossils were found on the Isle of Wight in southern England. The type species is C. oweni.

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

Calamosaurus was a genus of small theropod dinosaur from the Barremian-age Lower Cretaceous Wessex Formation of the Isle of Wight, England. It is based on two cervical vertebrae, collected by Reverend William Fox.

Eucamerotus was a genus of sauropod dinosaur from the Barremian-age Lower Cretaceous Wessex Formation (Wealden) of the Isle of Wight, England.

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

Oplosaurus was a genus of sauropod dinosaur from the Barremian-age Lower Cretaceous Wessex Formation of the Isle of Wight, England. It is known from a single tooth usually referred to the contemporaneous "wastebasket taxon" Pelorosaurus, although there is no solid evidence for this.

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

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<span class="mw-page-title-main">Wessex Formation</span> Early Cretaceous geological formation in England

The Wessex Formation is a fossil-rich English geological formation that dates from the Berriasian to Barremian stages of the Early Cretaceous. It forms part of the Wealden Group and underlies the younger Vectis Formation and overlies the Durlston Formation. The dominant lithology of this unit is mudstone with some interbedded sandstones. It is part of the strata of the Wessex Basin, exposed in both the Isle of Purbeck and the Isle of Wight. While the Purbeck sections are largely barren of vertebrate remains, the Isle of Wight sections are well known for producing the richest and most diverse fauna in Early Cretaceous Europe.

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

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<i>Ichthyovenator</i> Genus of dinosaur

Ichthyovenator is a genus of spinosaurid dinosaur that lived in what is now Laos, sometime between 125 and 113 million years ago, during the Aptian stage of the Early Cretaceous period. It is known from fossils collected from the Grès supérieurs Formation of the Savannakhet Basin, the first of which were found in 2010, consisting of a partial skeleton without the skull or limbs. This specimen became the holotype of the new genus and species Ichthyovenator laosensis, and was described by palaeontologist Ronan Allain and colleagues in 2012. The generic name, meaning "fish hunter", refers to its assumed piscivorous lifestyle, while the specific name alludes to the country of Laos. In 2014, it was announced that more remains from the dig site had been recovered; these fossils included teeth, more vertebrae (backbones) and a pubic bone from the same individual.

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<i>Ceratosuchops</i> Genus of baryonychine spinosaur from the Early Cretaceous

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<i>Riparovenator</i> Genus of baryonychine spinosaur from the Early Cretaceous

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<i>Brighstoneus</i> Genus of hadrosauriform dinosaur

Brighstoneus is a genus of hadrosauriform dinosaur from the Early Cretaceous Wessex Formation of the Isle of Wight, England. The genus contains a single species, Brighstoneus simmondsi, known from a partial skeleton.

References

  1. ↑ "Neovenator salerii". Dinosaur Isle . Retrieved 3 January 2022.
  2. ↑ Hutt, S.; Simmonds, K.; Hullman, G. (1990). "Predatory dinosaurs from the Isle of Wight". Proceedings of the Isle of Wight Natural History and Archaeological Society. 9: 137–146.
  3. 1 2 Hutt, S.; Martill, D.M.; Barker, M.J. (1996). "The first European allosauroid dinosaur (Lower Cretaceous, Wealden Group, England)". Neues Jahrbuch für Geologie und Paläontologie - Monatshefte. 1996 (10): 635–644. doi:10.1127/njgpm/1996/1996/635.
  4. ↑ Hutt, S.C. 1999. Neovenator salerii: A new theropod dinosaur from the Wealden of the Isle of Wight: its status and significance for Theropod evolution. A thesis submitted for the award of degree of Master of Philosophy (unpublished). University of Portsmouth
  5. 1 2 3 Brusatte, S.L.; Benson, R.B.J.; Hutt (2008). "The osteology of Neovenator salerii (Dinosauria: Theropoda) from the Wealden Group (Barremian) of the Isle of Wight". Monograph of the Palaeontographical Society. 162 (631): 166.
  6. ↑ Néraudeau, Didier; Allain, Ronan; Ballèvre, Michel; Batten, David; Buffetaut, Eric; Colin, Jean-Paul; Dabard, Marie Pierre; Daviero-Gomez, Véronique; El Albani, Abderrazak; Gomez, Bernard; Grosheny, D; Le Loeuff, Jean; Leprince, A; Martín-Closas, Carles; Masure, Edwige; Mazin, J.-M; Philippe, Marc; Pouech, Joane; Tong, Haiyan; Vullo, Romain (2012). "The Hauterivian-Barremian lignitic bone bed of Angeac (Charente, south-west France): Stratigraphical, palaeobiological and palaeogeographical implications". Cretaceous Research. 37: 1–14. doi:10.1016/j.cretres.2012.01.006.
  7. ↑ Paul, Gregory S. (2016). The Princeton Field Guide to Dinosaurs. Princeton University Press. p. 104. ISBN   978-1-78684-190-2. OCLC   985402380.
  8. ↑ Dodson P., Weishampel D. B. & Osmólska H., The Dinosauria , 2nd edition (2004), University of North Carolina Press, p. 104.
  9. ↑ Brusatte, S. L. and Benson, R. B. J. and Hutt, S. (2008) The osteology of Neovenator salerii (Dinosauria: Theropoda) from the Wealden Group (Barremian) of the Isle of Wight. Other. Palaeontographical Society, Palaeontographical Society Monographs 162 (631).
  10. ↑ Naish, D., Hutt S. and Martill, D., 2001, "Saurischian dinosaurs 2: Theropods". In: Martill D. and Naish D. (eds.), Dinosaurs of the Isle of Wight The Palaeontological Association, pp. 242-309
  11. 1 2 3 Benson, R.B.J., Carrano, M.T and Brusatte, S.L. (2010). "A new clade of archaic large-bodied predatory dinosaurs (Theropoda: Allosauroidea) that survived to the latest Mesozoic." Naturwissenschaften, 97:71-78 . doi : 10.1007/s00114-009-0614-x
  12. ↑ Barker, C., Dyke, G., Naish, D., Newham, E. and Katsamenis, O., 2015, "Complex neurovascular network in the rostrum of Neovenator salerii", SVPCA 2015 abstracts, 78
  13. ↑ Novas, Fernando E. (2013). "Evolution of the carnivorous dinosaurs during the Cretaceous: The evidence from Patagonia". Cretaceous Research. 45: 174–215. doi:10.1016/j.cretres.2013.04.001. hdl: 11336/102037 .
  14. ↑ University of Southampton. "Sensitive faces helped dinosaurs eat, woo and take temperature." ScienceDaily. ScienceDaily, 27 June 2017
  15. ↑ Barker, Chris Tijani; Naish, Darren; Newham, Elis; Katsamenis, Orestis L.; Dyke, Gareth (2017). "Complex neuroanatomy in the rostrum of the Isle of Wight theropod Neovenator salerii". Scientific Reports. 7 (1): 3749. Bibcode:2017NatSR...7.3749B. doi:10.1038/s41598-017-03671-3. PMC   5473926 . PMID   28623335.
  16. ↑ Benoit, Florian Bouabdellah, Emily Lessner, and Julien (2022-01-20). "The rostral neurovascular system of Tyrannosaurus rex". Palaeontologia Electronica. 25 (1): 1–20. doi: 10.26879/1178 . ISSN   1094-8074.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  17. ↑ Molnar, R. E., 2001, Theropod paleopathology: a literature survey: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, p. 337-363.
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