From Wikipedia, the free encyclopedia
Jump to: navigation, search
Temporal range: Early Cretaceous, 130–125 Ma
Baryonyx NHM.jpg
Reconstructed skeleton, Natural History Museum, London
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Theropoda
Family: Spinosauridae
Subfamily: Baryonychinae
Genus: Baryonyx
Charig & Milner, 1986
Species: † B. walkeri
Binomial name
Baryonyx walkeri
Charig & Milner, 1986

Baryonyx (/ˌbæriˈɒnɨks/) is a genus of theropod dinosaur. The holotype specimen was discovered in 1983 in Surrey, United Kingdom, and the animal was named Baryonyx walkeri in 1986. The genus name means "heavy claw", and the species name refers to its discoverer. Fragmentary specimens were later discovered in other parts of Britain and Iberia. Its fossils have been recovered from geological formations dating to the Barremian stage of the early Cretaceous Period, around 130–125 million years ago. The holotype specimen is one of the most complete theropod skeletons from Britain, and its discovery attracted the attention of the media.

Baryonyx was about 7.5 m (25 ft) long and weighed 1.2 tonnes (2645 lb), but the type specimen may not have been fully grown. It had a long, low snout and narrow jaws, which have been compared to those of a gharial. The tip of the snout expanded to the sides in a "rosette"-shape, and behind this the upper jaw had a notch that fit with the lower jaw, which curved upwards in the same area. It had a triangular crest on the top of its nasal bones. It had many finely serrated, conical teeth, with the largest ones in the front. The neck was straight compared to that of other theropods, and the neural spines of its back vertebrae increased in height from front to back. It had robust forelimbs, and bore a very large claw on its first finger, about 31 cm (12 in) long.

Baryonyx is a member of the family Spinosauridae, but its affinities were obscure upon its discovery. Apart from the type species, B. walkeri, some researchers have suggested that Suchomimus tenerensis belongs in the same genus, and that Suchosaurus cultridens is a senior synonym, but subsequent authors have kept them separate. Baryonyx is known to have been piscivorous (fish-eating), as evidenced by fish scales in the stomach region of the type specimen, but it may also have been an active predator of larger prey and scavenger, as it also contained bones of a juvenile Iguanodon. It would mainly have caught and processed its prey with the forelimbs and large claws. Baryonyx lived near water bodies, in areas where other theropod, ornithopod, and sauropod dinosaurs have also been found.


Size of spinosaurids (Baryonyx in orange) compared to a human

Baryonyx is estimated to have been 7.5 m (25 ft) long and to have weighed 1.2 tonnes (2645 lb).[1] The fact that various elements of the skull and vertebral column of the B. walkeri holotype specimen do not appear to have been co-ossified (fused), suggests that the individual was not fully grown, and that the mature animal could have been much larger, as attested by the vast size of the related Spinosaurus. That the sternum was fused might instead indicate that the specimen was fairly mature.[2]

The skull of Baryonyx is incompletely known, and much of the middle and hind parts are not preserved. The skull was elongated, and the front 170 mm (6.6 in) of the premaxillae formed a long, low snout or rostrum, with a rounded upper surface. The nostrils were far back from the tip, and passed horizontally from one side of the skull to the other. The front 130 mm (5.1 in) of the snout expanded into a spatulate (flared outwards to the sides), "terminal rosette" shape, similar to the modern gharial, and the front 70 mm (2.7 in) of the lower margin was down-turned. The snout was very narrow just behind the "rosette". The maxilla an premaxilla fit together by a complex articulation, resulting in the tooth row being strongly curved. This gap in the row is comparable to that of Dilophosaurus. The front 140 mm (5.5 in) of the dentary of the mandible curved upwards towards this area, and the gap between the upper and lower jaw has been termed the "subrostral notch". The snout had extensive pits, which would have served as exits for blood vessels and nerves. The maxilla appears to have housed sinuses.[2]

Snout of the holotype specimen from the left side and below

Baryonyx had a rudimentary secondary palate, similar to crocodiles, but unlike most theropod dinosaurs.[3] A rugose surface suggests the presence of a horny pad in the roof of the mouth. The upper midline of the nasal bones had a triangular sagittal crest, which was narrow and sharp at the front. The lacrimal bone appears to have formed a horn-core, similar to those seen on for example Allosaurus. The dentary was very long and shallow, and it had a prominent Meckelian groove. The rest of the lower jaw was very fragile, and the hind third was much thinner than the front, having a blade-like appearance. The front part of the dentary curved outwards to accommodate the large teeth at the front, and this area formed the mandibular part of the "rosette". The dentary had many foramina (openings), which served as passages for nerves and blood vessels.[2] It has been suggested that some of the cranial bones of Baryonyx had previously been misidentified, resulting in the occiput being reconstructed as too deep, and that the skull was probably as low, long and narrow as that of the closely related genus Suchomimus.[4]

Restoration of Baryonyx with a fish

Most of the teeth found with the type specimen were not attached to the skull; a few remained in the upper jaw, and only small replacement teeth were inside the lower jaw. The teeth had the shape of recurved cones, flattened somewhat sideways. The larger teeth were less recurved than the small ones, but they were otherwise uniform. The roots were very long, and the teeth were slender overall. The carinae (edges) of the teeth were finely serrated with denticles on the front and back. There were seven denticles for every millimetre (0.039 in), more than in most theropods, which were narrow and uniform in size. The teeth were also fluted with six to eight ridges along their length. The tooth enamel was finely granular. The inner side of each tooth row had a bony wall. The number of teeth was very large, with seven teeth on the right premaxilla, where other theropods have five, and thirty two in the dentary, where sixteen is the typical number. The entire lower jaw would have had sixty four teeth. The disparity between the number of teeth in the upper and lower jaws is usually not as pronounced in other theropods. The teeth in the dentary were also much more densely packed than those in the maxilla, and probably smaller. The "terminal rosette" had thirteen dental alveoli (tooth-sockets) in all; the first four were large, with the second and third being the largest, while the fourth and fifth progressively decreased in size. The diameter of the largest was twice that of the smallest. The alveoli of the dentary were more regular in size, but the first four were larger than the rest, and corresponded to the tip of the upper jaw. There were interdental plates between the alveoli.[2]

Skeletal diagram of the holotype specimen, showing known remains

The shape of the cervical vertebrae of the neck show that it tapered towards the head. They also became progressively longer from front to back. The neck was rather straight compared to that of other theropods, and did not form the typical sigmoid curve. The neural spines of the cervical vertebrae were low, thin, and were not always sutured to the centra, or bodies of the vertebrae. The axis vertebra was small compared to the size of the skull, and had a well-developed hyposphene. The centra of the dorsal vertebrae in the back were almost all similar in size. As is common among dinosaurs, Baryonyx reduced its weight with fenestra (skeletal pneumaticity) in the neural arches and with pleurocoels in the centra, mainly close to the transverse processes. From front to back, the neural spines of the dorsal vertebrae steadily changed from short and stout to tall and broad.[2]

The scapulae (shoulder blades) were robust and blade-like. The bones of the forelimb were short in relation to the size of the animal, but also very robust and wide. The humerus was short, stout, and stubby, and its ends were broadly expanded and flattened, the upper side for the deltopectoral crest and muscle attachment, the lower for articulation with the radius bone and ulna bone. The radius was short, stout and straight. The olecranon of the ulna appears to have been very powerful. The lower part of the ulna had a broad expansion. The first finger bore a very large claw (ungual bone), which measured about 31 cm (12 in) along its curve, but would have been considerably lengthened by a keratin sheath in life. Apart from its size, the proportions of this claw were fairly typical for a theropod; it was bilaterally symmetric, little compressed, smoothly rounded, and sharply pointed. A groove for the sheath ran along the length of the claw. The pubic foot of the pelvis was not expanded.[2]

History of discovery[edit]

Cast of the hand claw, Palais de la Découverte

In January 1983, amateur fossil hunter William J. Walker discovered a large claw, a phalanx bone, and part of a rib in a clay pit, called Smokejacks Pit, near Ockley in Surrey, United Kingdom. The tip of the claw was missing, but Walker found it a week later. British palaeontologists Alan J. Charig and Angela C. Milner examined these finds at the Natural History Museum of London, and found more bones after visiting the site in February, but the entire skeleton could not be collected until May–June due to conditions at the pit. A team of eight museum staff members and some volunteers excavated two tonnes of matrix. Walker donated the claw to the museum, and the Ockley Brick Company which owned the pit donated the rest of the skeleton, and provided equipment.[2][5] Though the area had been explored for 200 years, no similar remains had ever been found before.[6]

Most of the bones collected were encased in siltstone nodules, surrounded by fine sand and silt, with the rest lying in clay. The bones were disarticulated, and were scattered in a 5m x 2m area, but most were not far from their natural positions. The position of some bones was disturbed by a bulldozer, and some bones were broken by mechanical equipment before they were collected. Preparing the specimen was difficult, as the siltstone matrix was hard, and due to the presence of siderite; acid preparation was attempted, but most of the matrix was removed mechanically. The skeleton consisted of partial skull bones, teeth, cervical, dorsal and caudal vertebrae, ribs, the sternum, coracoids, arm and hand bones, claws, hip bones, and leg bones.[2][7] The original specimen number was BMNH R9951, but is now NHMUK VP R9951.[7][8]

Reconstructed head and arm, NHM

In 1986, Charig and Milner made the skeleton the holotype specimen of a new genus and species, Baryonyx walkeri. The genus name is Greek; βαρύς/barys means "heavy" or "strong" and ὄνυξ/onyx means "claw" or "talon", while the specific name refers to Walker, for discovering the specimen. At this time, the authors did not know whether the large claw belonged to the hand or the foot. Due to ongoing work on the bones (70% had been prepared at the time), the authors conceded that their article was only preliminary (a "Letter to Nature"), and that a more detailed description would be published at a later date. Baryonyx was the first large Early Cretaceous theropod found anywhere in the world until that point.[7] Until the discovery of Baryonyx, the last significant theropod find in Britain was Eustreptospondylus in 1871.[2] In a 1986 interview, Charig stated that Baryonyx was "the best find of the century" in Europe.[5] Upon its announcement, Baryonyx was widely featured in international media, and its discovery was the subject of a 1987 BBC documentary. Baryonyx received the nickname "Claws" from journalists, in reference to the film Jaws. The skeleton can now be seen mounted at the Natural History Museum.[6] In 1997, Charig and Milner published a full monograph describing the holotype skeleton in detail.[2]

Fossils from other parts of Britain and Iberia, mainly isolated teeth, have subsequently been referred to Baryonyx or similar animals.[2] Isolated teeth and bones, including hand bones and a vertebra, from the Isle of Wight have been attributed to this genus.[9] A maxilla fragment from La Roja in Spain was referred in 1995.[10] In 1999, a partial skull was reported from the Sala de los Infantes deposit of Burgos Province, Spain.[11] Dinosaur tracks from near Burgos have been identified as belonging to Baryonyx or another similar theropod.[12] In 2011, a specimen from the Papo Seco Formation in Boca do Chapim, Portugal, including a fragmentary dentary, teeth, vertebrae, ribs, hip bones, a scapula, and a phalanx bone, was attributed to Baryonyx, representing the most complete remains of this animal from Iberia.[13]


Skeletal diagram of the closely related genus Suchomimus

In their original description, Charig and Milner found Baryonyx to be unique enough to warrant a new family of theropod dinosaurs, Baryonychidae. Though they found Baryonyx to be unlike any other theropod group (and even considered the possibility that it was a thecodont due to apparent primitive features), they noted that the articulation of the maxilla and premaxilla was similar to that seen in Dilophosaurus. They also noted that two fragmentary snouts from Niger assigned to the family Spinosauridae by French paleontologist Philippe Taquet in 1984 appeared almost identical to those of Baryonyx, and referred them to Baryonychidae instead.[7] In 1988, American paleontologist Gregory S. Paul agreed with Taquet that Spinosaurus, described in 1915 based on fragmentary remains from Egypt (which were destroyed in WW2), and Baryonyx were similar, and due to their kinked snouts, were possibly late surviving dilophosaurs.[14] French palaeontologist Eric Buffetaut also supported this relationship in 1989.[15] In 1990, Charig and Milner dismissed the supposed spinosaurid affinities of Baryonyx, as they did not find their remains similar enough.[16]

In the 1990s, new discoveries shed more light on the relationships of Baryonyx and its relatives. In 1996, a snout from Morocco was referred to Spinosaurus, and Irritator from Brazil was named.[17] In 1998, the snout fragments from Niger were named Cristatusaurus, and Suchomimus was named from a partial skeleton also from there. In their description of Suchomimus, Sereno and colleagues placed it and Baryonyx in the new subfamily Baryonychinae within Spinosauridae, while other members of the group were placed in the subfamily Spinosaurinae.[18][4] In addition, they united the spinosaurids and their closest relatives in the superfamily Spinosauroidea, but in 2010, Roger Benson deemed this a junior synonym of Megalosauroidea, an older name.[19] The following cladogram shows the position of Baryonyx within Spinosauridae, after Allain et al., 2012:[20]

Holotype tooth of Suchosaurus cultridens







The authors of a 2002 article about Irritator proposed that Suchomimus tenerensis was similar enough to B. walkeri to be considered a species within the same genus, as B. tenerensis. They also suggested that Suchomimus was identical to Cristatusaurus, both from the Elrhaz Formation.[21] In a 2004 conference abstract, palaeontologists Steve Hutt and Penny Newbery supported this view based on a large theropod vertebra from the Isle of Wight that they attributed to Baryonyx, which indicated the vertebrae of the two genera were more similar than previously thought.[22] Later studies have kept the two genera separate.[23][20][13]

Fragmentary type mandible and tooth of Suchosaurus girardi

In a 2003 article, Milner noted that the teeth of Baryonyx were very similar to those of the genus Suchosaurus, and suggested their remains represented the same animal.[24] The type species of this genus, S. cultridens, was named in 1841 based on teeth from Tilgate Forest, Sussex, and a second species, S. girardi, was named in 1897 based on jaw fragments and a tooth from Boca do Chapim. In 2007, Buffetaut considered the teeth of S. girardi very similar to those of Baryonyx, apart from the stronger development of the crown ribs, and suggested the remains belonged to the same genus. Buffetaut also agreed with Milner that the teeth of S. cultridens were almost identical to those of B. walkeri, though with a more ribbed surface. The former taxon might therefore be a senior synonym of the latter, as it was published first, depending on whether the differences were interpreted as variation within the same taxon or between distinct ones. Buffetaut noted that as the holotype specimen of S. cultridens is a single, worn tooth, whereas that of B. walkeri is a skeleton, it might be more practical to retain the newer name.[25] In 2011, Octávio Mateus and colleagues agreed that Suchosaurus was closely related to Baryonyx, but considered both species in the former genus nomina dubia (dubious names), since their type specimens were not considered diagnostic (lacking distinguishing features), and could therefore not be definitely equated with other taxa.[13]


Model snout, showing the distinct "subrostral notch", NHM

Spinosaurids appear to have occurred widely during the Barremian to the Cenomanian ages of the Cretaceous, about 130 to 95 million years ago. They shared features such as the long and narrow, crocodile-like skulls, sub-circular teeth with fine to no serrations, the snout "rosette", and a secondary palate, which made them more resistant to torsion. By contrast, the primitive and typical condition for theropods is a tall and narrow snout, with blade-like teeth serrated along the front and back. The skull adaptations of spinosaurids converged with those of crocodilians, as the early members of that group had skulls similar to typical theropods, but later evolved elongated snouts, conical teeth, and secondary palates. These adaptations may be the result of their diet shifting from terrestrial prey to fish. Unlike crocodiles, the post-cranial skeletons of most spinosaurids do not appear to have aquatic adaptations, with the exception of Spinosaurus.[26][27] Sereno and colleagues proposed that the large thumb-claw and robust forelimbs of spinosaurids evolved in the Middle Jurassic, before the elongation of the skull and other adaptations related to fish-eating, as the former features are shared with their megalosaurid relatives. They also proposed that the spinosaurines and the baryonychines diverged before the Barremian age of the Early Cretaceous.[4]

Various theories have been proposed regarding the biogeography of the spinosaurids. Since Suchomimus was closer related to Baryonyx from Europe than to Spinosaurus, though that genus also lived in Africa, the distribution of spinosaurids cannot be strictly explained as vicariance resulting from continental rifting. Sereno et al. proposed that spinosaurids were initially distributed across the supercontinent Pangea, but were then split when the Tethys Sea opened; spinosaurines would then have evolved in the south (Gondwanaland: Africa and South America), and baryonychines in the north (Laurasia: Europe), with Suchomimus being the result of a single dispersal event from north to south.[4] It has also been suggested that baryonychines could be the ancestors of the more derived spinosaurines, which appear to have replaced the former in Africa.[28] In 2006, it was demonstrated that Iberia was close to northern Africa during the Early Cretaceous, and some researchers have therefore argued that the Iberian region acted as a "stepping-stone" between Europe and Africa, which is supported by the presence of baryonychines in Iberia. It is still unknown whether the dispersal took place from Europe to Africa or the opposite.[25] Subsequent discoveries of spinosaurid remains in Asia and Australia indicate that their dispersal may have been even more complicated.[13]


Animatronics display depicting Baryonyx hunting fish, NHM

In 1986, Charig and Milner first suggested that the elongated snout with its many, finely serrated teeth indicated that Baryonyx was piscivorous (a fish-eater), and speculated that it would crouch on a riverbank, using its claw for "gaffing" fish out of the water, similar to the modern grizzly bear. In 1984, Taquet had pointed out that the spinosaurid snouts from Niger were similar to those of the modern gharial, and suggested a behaviour similar to herons or storks. Angela and Milner did not consider Baryonyx aquatic, due to the nostrils being placed on the sides of the snout, far from the tip, and the form of the post-cranial skeleton, but still thought it capable of swimming, like most land-vertebrates. They initially proposed that the articulation between the premaxilla and maxilla was mobile, but later rejected this.[7][2]

In 1987, Andrew Kitchener disputed the piscivorous behaviour of Baryonyx, and suggested it would instead have been a scavenger that used its long neck to feed on ground level, using the claws to break into carcasses, and the long snout with nostrils far back for breathing while investigating the body cavity. He also argued that Baryonyx had too weak jaws and teeth to kill other dinosaurs, was too heavy to be manoeuvrable enough to catch fish, and that it had too many adaptations for piscivory.[29] R. E. H. Reid countered that a scavenged carcass would already have been broken up by the predator that killed it, and that large animals such as grizzly bears are capable of catching fish, at least in shallow water.[30]

The skull of the modern gharial has been compared to that of Baryonyx

In 1997, Charig and Milner pointed out that there was direct evidence of diet within the stomach region of the B. walkeri holotype; it contained acid-etched scales and teeth of the common fish Scheenstia (then classified in the genus Lepidotes), and abraded bones of a young Iguanodon. An apparent gastrolith was also found. They also mentioned circumstantial evidence, such as crocodile-like adaptations for catching and swallowing prey: the long and narrow jaws with their "terminal rosette", similar to those of a gharial, and the downturned tip and notch of the snout. In their view, these adaptations suggested that Baryonyx would have caught small to moderate sized fish in the manner of a crocodilian, by gripping them with the notch of the snout (the teeth here had a "stabbing function"), tilting the head backwards, and swallowing them head-first. Larger fish would be broken up with the claws. That the teeth in the lower jaw were smaller, more crowded and numerous than those in the upper jaw may have helped when gripping food. Charig and Milner maintained that Baryonyx would mainly have eaten fish, though it would also had been an active predator and opportunistic scavenger, but not equipped to be a typical macro-predator, like for example Allosaurus. They also suggested that Baryonyx mainly used its forelimbs and large claws when catching and killing larger prey, as well as tearing it apart afterwards.[2][31] In 2004, a pterosaur neck vertebra from Brazil with a spinosaurid tooth embedded in it confirmed that they were not exclusively piscivorous.[32]

CT scan of the holotype snout

In 2007, a Finite Element Analysis of CT scanned snouts indicated that the biomechanics of Baryonyx were most similar to those of the gharial, and unlike those of the American alligator and more conventional theropods, which supported a piscivorous diet for spinosaurids. Their secondary palate helped spinosaurids resist bending and torsion in their tubular snouts.[3] A 2013 study compared the biomechanics of CT-scanned spinosaurid snouts with those of extant crocodilians through Beam Theory, and found that the snouts of Baryonyx and Spinosaurus were similar to each other in their resistance to bending and torsion. Contrary to the 2007 study, the authors concluded that Baryonyx performed differently than the gharial, and concluded that spinosaurids were not obligate piscivores, but that their diet was determined by the size of the individual animal.[8]

A 2010 study proposed that spinosaurids were semi-aquatic, based on the oxygen isotope composition of spinosaurid teeth from around the world, compared with that of other theropods and extant animals. Spinosaurids likely spent much of the day in water, like crocodiles and hippopotamuses, and probably had a similar diet to the former, both being opportunistic predators. Since most spinosaurids do not appear to have anatomical adaptations for an aquatic lifestyle, the authors proposed that submerging in water was a mean to thermoregulation, like crocodiles and hippopotamuses. Spinosaurids may also have turned to aquatic habitats and piscivory to avoid competition with more terrestrial large theropods from the same localities.[33]

In their original description, Charig and Milner speculated that the elongated skull, long neck and strong humerus of Baryonyx indicated that the animal was at least a facultative quadruped, which would be unique among theropods.[7] In their 1997 article, they found no skeletal support for this, but stated that the forelimbs would have been strong enough for a quadrupedal posture, and that it would likely have caught aquatic prey while crouching or on all fours, by or in water.[2] In the 2014 re-description of Spinosaurus based on new remains, the authors suggested obligate quadrupedality for this animal, based on the anterior location of its centre of body mass. They found quadrupedality unlikely for Baryonyx, as the more completely known legs of the closely related Suchomimus did not support this posture.[27]


Restoration of a sunbathing Baryonyx being groomed by small pterosaurs and birds

The Weald Clay formation consists of sediments of Hauterivian (Lower Weald Clay) to Barremian (Upper Weald Clay) in age, which is about 130-125 million years old. The B. walkeri holotype was found in the latter, in clay that represents non-marine still water, which has been interpreted as a fluvial or mud plain environment with shallow water, lagoons, and marsh. During the Early Cretaceous, the Weald area (of Surrey, Sussex, and Kent) was partly covered by the large Wealden Lake, which contained fresh to brackish water. Two large rivers spread from the north area, where London now stands, which ran into the lake through a river delta, and the Anglo-Paris Basin lay at the south of the area. The climate in this area was sub-tropical, similar to the present Mediterranean region. Since the Smokejacks locality consists of different stratigraphic levels, not all of the fossil taxa found there were necessarily contemporaneous.[2] Dinosaurs from the locality include the ornithopods Mantellisaurus, Iguanodon, and small sauropods. Other vertebrates include sharks, such as Hybodus, bony fishes, including Scheenstia, crocodiles, and pterosaurs. Members of ten orders of insects have been identified, including Valditermes, Archisphex, and Pterinoblattina. Other invertebrates include ostracods, isopods, conchostracans, and bivalves. The plant Weichselia was common, and so was Bevhalstia, an aquatic herbaceous plant. Other plants include ferns, horsetails, club mosses, and conifers.[34]

Model depicting the carcase of the holotype specimen, NHM

Charig and Milner presented a possible a scenario explaining the taphonomy of the holotype specimen of B. walkeri (changes happening during fossilisation of the remains). The fine grained sediments around the skeleton, and the fact that the bones were found close together (skull and forelimb elements were in one end of the excavation area, pelvis and hind limb elements in the other), indicates that the environment was quiet at the time of fossilisation, and that water currents did not carry the carcase far, possibly because the water was too shallow. The area where the specimen died also seems to have been a suitable territory for a piscivorous animal. It may have caught fish and scavenged on the mudplain, becoming mired at some point, when it died and was buried. As the bones are well-preserved and had no gnaw-marks, the carcase appears to have been undisturbed by scavengers, which suggests it was rapidly covered in sediment. The dis-articulation of the bones may therefore have been the result of decomposition of the soft tissue. Parts of the skeleton appear to have since weathered to different degrees, perhaps because water levels changed or the sediments were shifted, which exposed parts of the skeleton. The girdle and limb bones, the dentary, and a rib-shaft were broken before fossilisation, perhaps due to being trampled by large animals while buried. The orientation of the bones indicate the carcase lay on its back, which may explain why all the lower teeth had fallen out of their sockets, while some of the upper ones were still in place.[2]

Other dinosaurs from the Wessex Formation of the Isle of Wight include the theropods Neovenator, Aristosuchus, Thecocoelurus, Calamospondylus, and Ornithodesmus, the ornithopods Iguanodon, Hypsilophodon, and Valdosaurus, the sauropods Pelorosaurus and Chondrosteosaurus, and the ankylosaur Polacanthus.[35] The Papo Seco Formation of Portugal where Baryonyx has been identified is composed of marl and represents a lagoonal environment. Other dinosaur remains from there include fragments that have been tentatively assigned to Mantellisaurus, a macronarian sauropod, and Megalosaurus.[25][13]


  1. ^ Paul, G.S. (2010). The Princeton Field Guide to Dinosaurs. Princeton University Press. p. 87. ISBN 978-0-691-13720-9. 
  2. ^ a b c d e f g h i j k l m n o p Charig, A. J.; Milner, A. C. (1997). "Baryonyx walkeri, a fish-eating dinosaur from the Wealden of Surrey". Bulletin of the Natural History Museum of London 53: 11–70. 
  3. ^ a b Rayfield, E. J.; Milner, A. C.; Xuan, V. B.; Young, P. G. (2007). "Functional morphology of spinosaur 'crocodile-mimic' dinosaurs". Journal of Vertebrate Paleontology 27 (4): 892–901. doi:10.1671/0272-4634(2007)27[892:FMOSCD]2.0.CO;2. 
  4. ^ a b c d Sereno, P.C.; Beck, A. L.; Dutheil, D. B.; Gado, B.; Larsson, H. C. E.; Lyon, G. H.; Marcot, J. D.; Rauhut, O. W. M.; Sadleir, R. W.; Sidor, C. A.; Varricchio, D. D.; Wilson, G. P.; Wilson, J. A. (1998). "A long-snouted predatory dinosaur from Africa and the evolution of spinosaurids". Science 282 (5392): 1298–1302. Bibcode:1998Sci...282.1298S. doi:10.1126/science.282.5392.1298. PMID 9812890. Retrieved 2013-03-19. 
  5. ^ a b Edwards, D. D. (1986). "Fossil Claw Unearths a New Family Tree". Science News 130 (23): 356. doi:10.2307/3970849. JSTOR 3970849. 
  6. ^ a b Moody, R. T. J.; Naish, D. (2010). "Alan Jack Charig (1927-1997): An overview of his academic accomplishments and role in the world of fossil reptile research". Geological Society, London, Special Publications 343: 89. Bibcode:2010GSLSP.343...89M. doi:10.1144/SP343.6. 
  7. ^ a b c d e f Charig, A. J.; Milner, A. C. (1986). "Baryonyx, a remarkable new theropod dinosaur". Nature 324 (6095): 359–361. Bibcode:1986Natur.324..359C. doi:10.1038/324359a0. PMID 3785404. 
  8. ^ a b Cuff, A. R.; Rayfield, E. J. (2013). Farke, Andrew A, ed. "Feeding Mechanics in Spinosaurid Theropods and Extant Crocodilians". PLoS ONE 8 (5): e65295. Bibcode:2013PLoSO...865295C. doi:10.1371/journal.pone.0065295. PMC 3665537. PMID 23724135. 
  9. ^
  10. ^ I. Viera and J. A. Torres. 1995. Presencia de Baryonyx walkeri (Saurischia, Theropoda) en el Weald de La Rioja (España). Nota previa. Munibe 47:57-61
  11. ^ Fuentes Vidarte, C., M. Meijide Calvo, L. A. Izquierdo, D. Montero, G. Pérez, F. Torcida, V. Urién, F. Meijide Fuentes, and M. Meijide Fuentes. 2001. Restos fósiles de Baryonyx (Dinosauria, Theropoda) en el Cretácico Inferior de Salas de los Infantes (Burgos, España), pp. 349–359, in Actas de las I Jornadas Internacionales sobre Paleontología de Dinosaurios y su Entorno. Salas de los Infantes, Burgos.
  12. ^ Dinosaur Footprints and Trackways of La Rioja. Félix Pérez-Lorente. Series: Life of the Past. Pages 225-256 2015
  13. ^ a b c d e Mateus, O., Araújo, R., Natário, C. & Castanhinha, R. 2011. A new specimen of the theropod dinosaur Baryonyx from the early Cretaceous of Portugal and taxonomic validity of Suchosaurus. PDF Zootaxa 2827: 54–68.
  14. ^ Paul, Gregory S. (1988). Predatory Dinosaurs of the World. New York: Simon & Schuster. pp. 271–274. ISBN 0-671-61946-2. 
  15. ^ Buffetaut, E. (1989). – New remains of the enigmatic dinosaur Spinosaurus from the Cretaceous of Morocco and the affinities between Spinosaurus and Baryonyx.– N. Jb. Geol. Paläont. Mh., 2, 79-87.
  16. ^ Charig, A. J.; Milner, A. C. (1990). "The systematic position of Baryonyx walkeri, in the light of Gauthier's reclassification of the Theropoda". In Carpenter, K.; Currie, P. J. Dinosaur Systematics: Perspectives and Approaches. Cambridge University Press. pp. 127–140. ISBN 9780521438100. 
  17. ^ Russell, D.A. (1996). "Isolated dinosaur bones from the Middle Cretaceous of the Tafilalt, Morocco". Bulletin du Muséum National d'Histoire Naturelle, Paris, 4e série, section C 18 (2–3): 349–402. 
  18. ^ Taquet, P. and Russell, D.A. (1998). "New data on spinosaurid dinosaurs from the Early Cretaceous of the Sahara". Comptes Rendus de l'Académie des Sciences à Paris, Sciences de la Terre et des Planètes 327: 347-353
  19. ^ Benson, R.B.J. (2010). "A description of Megalosaurus bucklandii (Dinosauria: Theropoda) from the Bathonian of the UK and the relationships of Middle Jurassic theropods". Zoological Journal of the Linnean Society 158 (4): 882–935. doi:10.1111/j.1096-3642.2009.00569.x. 
  20. ^ a b Allain, R.; Xaisanavong, T.; Richir, P.; Khentavong, B. (2012). "The first definitive Asian spinosaurid (Dinosauria: Theropoda) from the early cretaceous of Laos". Naturwissenschaften 99 (5): 369–377. Bibcode:2012NW.....99..369A. doi:10.1007/s00114-012-0911-7. PMID 22528021. 
  21. ^ Sues, H.-D.; Frey, E.; Martill, M.; Scott, D.M. (2002). "Irritator challengeri, a spinosaurid (Dinosauria: Theropoda) from the Lower Cretaceous of Brazil". Journal of Vertebrate Paleontology 22 (3): 535–547. doi:10.1671/0272-4634(2002)022[0535:icasdt];2. 
  22. ^ Hutt, S. and Newbery, P. (2004). "A new look at Baryonyx walkeri (Charig and Milner, 1986) based upon a recent fossil find from the Wealden." Symposium of Vertebrate Palaeontology and Comparative Anatomy. (online abstract).
  23. ^ Benson, R. B. J.; Carrano, M. T.; Brusatte, S. L. (2009). "A new clade of archaic large-bodied predatory dinosaurs (Theropoda: Allosauroidea) that survived to the latest Mesozoic". Naturwissenschaften 97 (1): 71–78. Bibcode:2010NW.....97...71B. doi:10.1007/s00114-009-0614-x. PMID 19826771. 
  24. ^ Milner, A., 2003, "Fish-eating theropods: A short review of the systematics, biology and palaeobiogeography of spinosaurs". In: Huerta Hurtado and Torcida Fernandez-Baldor (eds.). Actas de las II Jornadas Internacionales sobre Paleontologýa de Dinosaurios y su Entorno (2001). pp 129-138
  25. ^ a b c Buffetaut, E. (2007). "The spinosaurid dinosaur Baryonyx (Saurischia, Theropoda) in the Early Cretaceous of Portugal". Geological Magazine 144 (6): 1021–1025. doi:10.1017/S0016756807003883. 
  26. ^ Holtz Jr., T. R. (1998). "PALEONTOLOGY:Spinosaurs as Crocodile Mimics". Science 282 (5392): 1276. doi:10.1126/science.282.5392.1276. 
  27. ^ a b Ibrahim, N.; Sereno, P. C.; Dal Sasso, C.; Maganuco, S.; Fabri, M.; Martill, D. M.; Zouhri, S.; Myhrvold, N.; Lurino, D. A. (2014). "Semiaquatic adaptations in a giant predatory dinosaur". Science 345 (6204): 1613–6. Bibcode:2014Sci...345.1613I. doi:10.1126/science.1258750. PMID 25213375.  Supplementary Information
  28. ^ Buffetaut, E.; Ouaja, M. (2002). "A new specimen of Spinosaurus (Dinosauria, Theropoda) from the Lower Cretaceous of Tunisia, with remarks on the evolutionary history of the Spinosauridae". Bulletin de la Société Géologique de France 173 (5): 415. doi:10.2113/173.5.415.  edit
  29. ^ Kitchener, A. (1987). "Function of Claws' claws". Nature 325 (6100): 114. Bibcode:1987Natur.325..114K. doi:10.1038/325114a0. 
  30. ^ Reid, R. E. H. (1987). "Claws' claws". Nature 325 (6104): 487. Bibcode:1987Natur.325..487R. doi:10.1038/325487b0. 
  31. ^ López-Arbarello, A. (2012). "Phylogenetic Interrelationships of Ginglymodian Fishes (Actinopterygii: Neopterygii)". PLoS ONE 7 (7): e39370. Bibcode:2012PLoSO...739370L. doi:10.1371/journal.pone.0039370. PMC 3394768. PMID 22808031. 
  32. ^ Buffetaut, E.; Martill, D.; Escuillié, F. (2004). "Pterosaurs as part of a spinosaur diet". Nature 429 (6995): 33. Bibcode:2004Natur.429...33B. doi:10.1038/430033a. 
  33. ^ Amiot, R.; Buffetaut, E.; Lecuyer, C.; Wang, X.; Boudad, L.; Ding, Z.; Fourel, F.; Hutt, S.; Martineau, F.; Medeiros, M. A.; Mo, J.; Simon, L.; Suteethorn, V.; Sweetman, S.; Tong, H.; Zhang, F.; Zhou, Z. (2010). "Oxygen isotope evidence for semi-aquatic habits among spinosaurid theropods". Geology 38 (2): 139. Bibcode:2010Geo....38..139A. doi:10.1130/G30402.1. 
  34. ^ Ross, A. J.; Cook, E. (1995). "The stratigraphy and palaeontology of the Upper Weald Clay (Barremian) at Smokejacks Brickworks, Ockley, Surrey, England". Cretaceous Research 16 (6): 705–716. doi:10.1006/cres.1995.1044. 
  35. ^ Martill, D. M.; Hutt, S. (1996). "Possible baryonychid dinosaur teeth from the Wessex Formation (Lower Cretaceous, Barremian) of the Isle of Wight, England". Proceedings of the Geologists' Association 107 (2): 81. doi:10.1016/S0016-7878(96)80001-0. 

External links[edit]