Neovenator (nˈiːə͡ʊvˌɛne͡ɪtə; "new hunter") is an extinct genus of carcharodontosaurian theropod dinosaur. It is known primarily from several skeletons found in the Early Cretaceous (Hauterivian–Barremian) Wessex Formation on the south coast of the Isle of Wight, southern England. The first remains of Neovenator were discovered in 1978 alongside those of the ornithopod Brighstoneus, after the collapse of part of Grange Chine. In 1996, Steve Hutt, David Martill and Michael Barker named the genus Neovenator. One species is known: the type species, N. salerii, after the Salero family who owned the site on which its remains were discovered.
Between the type specimen and multiple referred specimens, roughly seventy per cent of Neovenators skeleton is known. While incompletely known, it was likely around in length, and probably weighed , though a specimen possibly referrable to the genus indicates a larger body size of . Its skull is known from both premaxillae, parts of the left maxilla, right nasal, right palatine, and the front portion of a dentary. The snout of Neovenator is covered in rugosities, similar to carcharodontosaurids and abelisaurids, which indicates that it either had an extensive blood supply, possibly for thermoregulation, or an extensive neurovascular system, possibly for tactile purposes. However, this hypothesis has seen scrutiny. Teeth found in association with the type specimen of Neovenator, while they do possess the characteristic enamel wrinkles of carcharodontosaur teeth, differ in their precise pattern.
The taxonomic position of Neovenator has been a subject of debate. Prior to its description, its fragmentary remains led to a tentative referral to Megalosaurus. The authors who described the genus suggested that it was a British representative of Allosauridae, or at least closely related to Allosaurus. A position within the related clade Carcharodontosauria was first suggested in 1998, and subsequently saw support using both comparative morphology and phylogenetic analyses. In 2012, it was assigned to a family of its own, Neovenatoridae.
Neovenator is best known from the Wessex Formation of the Isle of Wight, although teeth possibly referrable to the genus have been recovered from the Angeac-Charente bone bed in France. Bite marks found on a fossil of the iguanodontid Mantellisaurus suggest that it was among Neovenators prey base. Like many fossils of the closely related Allosaurus, the type specimen of Neovenator bears numerous pathologies.
Discovery and species
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 geology student David Richards collected additional material. 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, palaeontologist 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 material. The theropod material, meanwhile, was fairly incomplete (consisting of vertebrae and fragments of the pelvis), and a lack of diagnostic features meant that it was ignored until its significance was recognised by Dr. William Blows.
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, the front of a mandible (lower jaw), most of the vertebral column, ribs, gastralia (belly ribs), chevrons, the left shoulder girdle, pelvic bones and a hindlimb. These were accessioned under numbers BMNH R10001 and MIWG 6348. From 1997–2001, further elements were recovered, in the form of the first caudal (tail) vertebra, a left femur, a right tibia, and a pedal phalanx (toe bone). In all, the bones recovered 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, recovered from the first. In 1987, Jenny Simmonds found a third skeleton, containing vertebra and pelvic bones, specimen MIWG.6352; this specimen was originally believed to be a different taxon. A fourth individual found by Nick Oliver is represented by specimen IWCMS 2002.186, consisting of a lower jaw, parts of the cervical (neck) 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.
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.
In 1999, Hutt dedicated his (unpublished) master thesis to Neovenator.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 This thesis would form the foundation for a monograph discussing the osteology of the genus. That monograph was published in 2008, and was authored by Stephen L. Brusatte, Roger B. J. Benson and Hutt by the Palaeontographical Society.
In 2012, teeth indistinguishable from those associated with the holotype of Neovenator were found in the Angeac-Charente bone bed, in France, dating to the Berriasian.Ronan Allain, Romain Vullo, Lee Rozada, Jérémy Anquetin, Renaud Bourgeais, et al.. Vertebrate paleobiodiversity of the Early Cretaceous (Berriasian) Angeac-Charente Lagerstätte (southwestern France): implications for continental faunal turnover at the J/K boundary. Geodiversitas, Museum National d'Histoire Naturelle Paris, In press. ffhal-03264773f They were distinguished from those of Erectopus, a basal allosauroid also known from the Early Cretaceous of France, by differences in the carinae of their teeth.
Description
Size Neovenator was a mid-sized, lightly built carcharodontosaurid. The holotype specimen measured approximately in length, and was fairly lightly built. A hip height of about has been suggested. Gregory S. Paul estimated its mass at around . It has been suggested that the holotype may be a subadult, and if this is the case, this may not be reflective of the maximum body size of the genus. However, in 2016, Jeremy Lockwood noted that most of the elements referred to Neovenator are roughly the same size as the holotype, suggesting that adults would have had a similar body size. Specimen MIWG 4199 indicates an individual with a possible length of about , though it consists only of a pedal phalanx and its position in Neovenator is dubious.Dodson, P.; Weishampel, D. B. & Osmólska, H., The Dinosauria, 2nd edition (2004), University of North Carolina Press, p. 104. A footprint (IWCMS:2016.273) is believed to have been left by an animal with a hip height of , and while the trackmaker is uncertain, it has been suggested that it was left by a mature Neovenator.
Skull and dentition The skull of Neovenator is not known in its entirety, but is instead represented by both premaxillae (both complete), a left maxilla, a right nasal, a right palatine, and the anterior (front) portion of a left dentary, part of the mandible. The premaxillae were longer than they were tall, measuring in length and in height. This condition is seen in several non-carcharodontosaurid taxa (i.e. Allosaurus and Sinraptor), but not in other, more derived carcharodontosaurs, such as Acrocanthosaurus. The premaxillae have an additional connection (referred to in 2001 as a "pen-in-socket connection"), by not seen in other theropods.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 The left maxilla, as preserved, measures around in length, and in depth. Only a small portion near where the jugal connected is missing. As in many basal tetanurans (and the more derived Carcharodontosaurus), the maxilla contributed to the posterior (rear) border of the external naris (nasal opening). Similar to abelisaurids and other allosauroids (i.e. Giganotosaurus, Mapusaurus and Sinraptor), the surface of the maxilla bore prominent rugosities, and contains a high density of foramina, particularly at its anteriormost (very front) portion, ventral to (below) the external naris. It has been suggested that Neovenators snout was highly vascularised or innervated.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 Unlike many other allosauroids and ceratosaurs, the ascending ramus lacked pneumatic excavation (hollow spaces containing air pockets). A large maxillary fenestra, with a diameter roughly one-sixth of the length of the tooth row, penetrated the maxilla. Similar to the maxilla, Neovenators nasal was rugose, though the extent of its rugosity is slightly weaker than in Carcharodontosaurus. The dorsal (upper) and lateral (side) surfaces of the nasal were separated by a rugose ridge. While initially regarded as a diagnostic feature of Neovenator, the same is also known in Allosaurus. As evidenced by the presence of a single large pneumatopore, the nasal was likely hollow and highly pneumatised. Similar conditions are observed in other allosauroids, though the amount of pneumatopores varied, sometimes within the same genus. Posteriorly, the dorsal portion of the nasals would have contributed to a crest similar to that of Allosaurus, though this crest differed in that it showed no lateral overhang.
The holotype of Neovenator preserved a near-complete left dentary, measuring in length and , though it was lost at the time of the 2008 monograph's publication. What was written in that monograph was therefore based on figures in published works and examinations of a cast. Unlike some other carcharodontosaurs (particularly later genera such as Carcharodontosaurus and Giganotosaurus), the anterior (front) tip of the dentary was not squared-off. It was instead rounded, as in most other theropods. Unlike the maxilla and nasal, the dentary of Neovenator was fairly smooth, lacking rugosities, unlike what is seen in taxa like Carcharodontosaurus. The largest foramina present were directly ventral to the alveolar margin (the tooth row), set in a longitudinal groove which deflected ventrally at around the fifth alveolus. The third alveolus of the dentary was enlarged, which is unique among allosauroids, save for Acrocanthosaurus. When viewed from above, the alveoli on both upper and lower jaws were arranged in a weakly sinuous curve, though this may be the result of taphonomy.