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Quetzalcoatlus northropi /kɛtsəlkoʊˈætləs/ is an azhdarchid pterosaur known from the Late Cretaceous of North America (Maastrichtian stage) and one of the largest known flying animals of all time. It is a member of the family Azhdarchidae, a family of advanced toothless pterosaurs with unusually long, stiffened necks. Its name comes from the Mesoamerican feathered serpent god Quetzalcoatl.When it was first named as a new species in 1975, scientists estimated that the largest Quetzalcoatlus fossils came from an individual with a wingspan as large as 15.9 meters (52 feet), choosing the middle of three extrapolations from the proportions of other pterosaurs that gave an estimate of 11, 15.5 and 21 meters respectively (36 feet, 50.85 feet, 68.9 feet). In 1981, further advanced studies lowered these estimates to 11–12 meters (36–39 ft).[2] More recent estimates based on greater knowledge of azhdarchid proportions place its wingspan at 10–11 meters (33–36 ft).[3] Remains found in Texas in 1971 indicate that this reptile had a minimum wingspan of about 11 metres.[4]

Mass estimates for giant azhdarchids are extremely problematic because no existing species share a similar size or body plan, and in consequence published results vary widely. Generalized height in a bipedal stance, based off of its wingspan, would have been at least 3 meters, (13 feet), much higher than a human.[5] Generalized weight, based off of some studies have historically found extremely low weight estimates for Quetzalcoatlus, as low as 70 kilograms (150 lb) for a 10-meter (32-foot-10-inch) individual, a majority of estimates published since the 2000s have been higher, around 200–250 kilograms (440–550 lb).[6][7]
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Baryonyx (/ˌbæriˈɒnᵻks/) is a genus of theropod dinosaur which lived in the Barremian stage of the early Cretaceous Period, about 130–125 million years ago. The holotype specimen was discovered in 1983 in Surrey, England, and the animal was named Baryonyx walkeri in 1986. The genus 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 hunter William J. Walker. Fragmentary specimens were later discovered in other parts of the United Kingdom and Iberia. The holotype specimen is one of the most complete theropod skeletons from the UK, and its discovery attracted media attention.

Baryonyx was about 7.5 m (25 ft) long and weighed 1.2 t (1.3 short tons), but the holotype 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 the shape of a rosette. Behind this, the upper jaw had a notch which fitted into the lower jaw (which curved upwards in the same area). It had a triangular crest on the top of its nasal bones. Baryonyx had many finely serrated, conical teeth, with the largest teeth in front. The neck was less curved than that of other theropods, and the neural spines of its dorsal vertebrae increased in height from front to back. It had robust forelimbs, with the eponymous first-finger claw measuring about 31 cm (12 in) long.

Now recognised as a member of the family Spinosauridae, Baryonyx's affinities were obscure when it was discovered. 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; subsequent authors have kept them separate. Baryonyx was the first theropod dinosaur demonstrated to have been piscivorous (fish-eating), as evidenced by fish scales in the stomach region of the holotype specimen. It may also have been an active predator of larger prey and a scavenger, since it also contained bones of a juvenile Iguanodon. The creature would have caught and processed its prey primarily with its forelimbs and large claws. Baryonyx lived near water bodies, in areas where other theropod, ornithopod, and sauropod dinosaurs have also been found.
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Giganotosaurus (/ˌdʒaɪɡəˌnoʊtəˈsɔːrəs/ jig-ə-not-o-saw-rus[1]) is a genus of theropod dinosaur that lived in what is now Argentina, during the early Cenomanian age of the Late Cretaceous period, approximately 99.6 to 97 million years ago. The holotype specimen was discovered in the Candeleros Formation of Patagonia in 1993, and is almost 70% complete. The animal was named G. carolinii in 1995; the genus name translates as "giant southern lizard" and the specific name honours the discoverer, Rubén D. Carolini. A dentary bone, a tooth and some tracks, discovered before the holotype, were later assigned to this animal. The genus attracted much interest and became part of a scientific debate about the maximum sizes of theropod dinosaurs.

Giganotosaurus was one of the largest known terrestrial carnivores, but the exact size has been hard to determine due to the incompleteness of the remains found so far. Estimates for the most complete specimen range from a length of 12 to 13 m (39 to 43 ft), a skull 1.53 to 1.80 m (5.0 to 5.9 ft) in length, and a weight of 4.2 to 13.8 t (4.6 to 15.2 short tons). The dentary bone that belonged to a supposedly larger individual has been used to extrapolate a length of 13.2 m (43 ft). Some researchers have found the animal to be larger than Tyrannosaurus, which has historically been considered the largest theropod, while others have found them to be equal in size, and the largest size estimates for Giganotosaurus exaggerated. The skull was low, with rugose (rough and wrinkled) nasal bones and a ridge-like crest on the lacrimal bone in front of the eye. The front of the lower jaw was flattened, and had a downwards projecting process (or "chin") at the tip. The teeth were compressed sideways and had serrations. The neck was strong and the pectoral girdle proportionally small.

Part of the family Carcharodontosauridae, Giganotosaurus is one of the most completely known members of the group, which includes other very large theropods, such as the closely related Mapusaurus and Carcharodontosaurus. Giganotosaurus is thought to have been homeothermic (a type of "warm-bloodedness"), with a metabolism between that of a mammal and a reptile, which would have enabled fast growth. It may have been relatively slow-moving, with a running speed of 14 metres per second (50 km/h; 31 mph). It would have been capable of closing its jaws quickly, capturing and bringing down prey by delivering powerful bites. The "chin" may have helped in resisting stress when a bite was delivered against prey. Giganotosaurus is thought to have been the apex predator of its ecosystem, and it may have fed on juvenile sauropod dinosaurs.
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T. rex" redirects here. For the Marc Bolan fronted rock band, see T. Rex (band). For other uses, see T. Rex (disambiguation).
Tyrannosaurus
Temporal range: Late Cretaceous, 68–66 Ma
PreЄЄOSDCPTJKPgN

Tyrannosaurus Rex Holotype.jpg
Reconstruction of the T. rex type specimen (CM 9380) at the Carnegie Museum of Natural History
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Dinosauria
Order: Saurischia
Suborder: Theropoda
Family: †Tyrannosauridae
Subfamily: †Tyrannosaurinae
Tribe: †Tyrannosaurini
Osborn, 1906
Genus: †Tyrannosaurus
Osborn, 1905
Type species
†Tyrannosaurus rex
Osborn, 1905
Synonyms
Genus synonymy[show]
Species synonymy[show]
Tyrannosaurus (/tᵻˌrænəˈsɔːrəs/ or /taɪˌrænəˈsɔːrəs/, meaning "tyrant lizard", from the Ancient Greek tyrannos (τύραννος), "tyrant", and sauros (σαῦρος), "lizard"[1]) is a genus of coelurosaurian theropod dinosaur. The species Tyrannosaurus rex (rex meaning "king" in Latin), is one of the most well-represented of the large theropods. Tyrannosaurus lived throughout what is now western North America, on what was then an island continent known as Laramidia. Tyrannosaurus had a much wider range than other tyrannosaurids. Fossils are found in a variety of rock formations dating to the Maastrichtian age of the upper Cretaceous Period, 68 to 66 million years ago.[2] It was the last known member of the tyrannosaurids,[3] and among the last non-avian dinosaurs to exist before the Cretaceous–Paleogene extinction event.

Like other tyrannosaurids, Tyrannosaurus was a bipedal carnivore with a massive skull balanced by a long, heavy tail. Relative to its large and powerful hind limbs, Tyrannosaurus fore limbs were short but unusually powerful for their size and had two clawed digits. The most complete specimen measures up to 12.3 m (40 ft) in length,[4] up to 3.66 meters (12 ft) tall at the hips,[5] and according to most modern estimates 8.4 metric tons (9.3 short tons) to 18.5 metric tons (20.4 short tons) in weight.[4][6][7] Although other theropods rivaled or exceeded Tyrannosaurus rex in size, it is still among the largest known land predators and is estimated to have exerted the largest bite force among all terrestrial animals.[8][9] By far the largest carnivore in its environment, Tyrannosaurus rex was most likely an apex predator, preying upon hadrosaurs, armoured herbivores like ceratopsians and ankylosaurs, and possibly sauropods.[10] Some experts, however, have suggested the dinosaur was primarily a scavenger. The question of whether Tyrannosaurus was an apex predator or a pure scavenger was among the longest ongoing debates in paleontology.[11] It is accepted now that Tyrannosaurus rex acted as a predator, and opportunistically scavenged as modern mammalian and avian predators do.

More than 50 specimens of Tyrannosaurus rex have been identified, some of which are nearly complete skeletons. Soft tissue and proteins have been reported in at least one of these specimens. The abundance of fossil material has allowed significant research into many aspects of its biology, including its life history and biomechanics. The feeding habits, physiology and potential speed of Tyrannosaurus rex are a few subjects of debate. Its taxonomy is also controversial, as some scientists consider Tarbosaurus bataar from Asia to be a second Tyrannosaurus species while others maintain Tarbosaurus is a separate genus. Several other genera of North American tyrannosaurids have also been synonymized with Tyrannosaurus.

Contents [hide]
1 Description
1.1 Skin and feathers
2 Classification
3 Paleobiology
3.1 Life history
3.2 Sexual dimorphism
3.3 Posture
3.4 Arms
3.5 Soft tissue
3.6 Thermoregulation
3.7 Footprints
3.8 Locomotion
3.9 Brain and senses
3.10 Feeding strategies
3.10.1 Cannibalism
3.10.2 Pack behavior
3.11 Pathology
4 Paleoecology
5 History of research
5.1 Earliest finds
5.2 Manospondylus
5.3 Notable specimens
6 In popular culture
7 See also
8 References
9 Further reading
10 External links
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Dunkleosteus is an extinct genus of arthrodire placoderm fish that existed during the Late Devonian period, about 360–380 million years ago. Some of the species, such as D. terrelli, D. marsaisi, and D. magnificus, are among the largest arthrodire placoderms ever to have lived.

The largest species, D. terrelli, measuring up to 6 m (20 ft) long[1][2] and 1 t (1.1 short tons) in weight,[1] was a hypercarnivorous apex predator. Few other placoderms, save, perhaps, its contemporary Titanichthys, rivaled Dunkleosteus in size.

Dunkleosteus is a pachyosteomorph arthrodire originally placed in the family Dinichthyidae, a family composed mostly of large, carnivorous arthrodires like Gorgonichthys. Anderson (2009) suggests, because of its primitive jaw structure, Dunkleosteus should be placed outside the family Dinichthyidae, perhaps close to the base of the clade Pachyosteomorpha, near Eastmanosteus. Carr and Hlavin (2010) resurrect Dunkleosteidae and place Dunkleosteus, Eastmanosteus, and a few other genera from Dinichthyidae within it.[3] (Dinichthyidae, in turn, is made into a monospecific family[4]).

New studies have revealed several features in both its food and biomechanics, as well as its ecology and physiology. Placodermi first appeared in the Silurian, and the group became extinct during the transition from the Devonian to the Carboniferous, leaving no descendants. The class persisted in the fossil record for at least 70 million years, in comparison to the 400-million-year-long history of sharks.[5]

In recent decades, Dunkleosteus has achieved recognition in popular culture, with a large number of specimens on display, and notable appearances in entertainment media like Sea Monsters - A Walking with Dinosaurs Trilogy and River Monsters. Numerous fossils of some species have been found in North America, Poland, Belgium, and Morocco. The name Dunkleosteus combines the Greek osteus (οστεος), meaning "bone", and Dunkle, in honor of David Dunkle of the Cleveland Museum of Natural History.
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Plesiosaurus (Greek: πλησιος/plesios, near to + σαυρος/sauros, lizard) is a genus of extinct, large marine sauropterygian reptile that lived during the early part of the Jurassic Period, and is known by nearly complete skeletons from the Lias of England. Although there are a number of modern-day myths surrounding this order of creature, such as the myth of the Loch Ness Monster, these creatures are known to be extinct. It is distinguishable by its small head, long and slender neck, broad turtle-like body, a short tail, and two pairs of large, elongated paddles. It lends its name to the order Plesiosauria, of which it is an early, but fairly typical member. It contains only one species, Plesiosaurus dolichodeirus. P. brachypterygius, P. guilielmiiperatoris, and P. tournemirensis were assigned to new genera, Hydrorion, Seeleyosaurus and Occitanosaurus.

Contents [hide]
1 Description
1.1 Skull and dentition
1.2 Vertebral column
1.3 Limbs
2 Discovery
3 Classification
4 Stratigraphy
5 Paleoecology
6 See also
7 References
7.1 Notes
7.2 Sources
8 External links
Plesiosaurus
Temporal range: Early Jurassic, 199.6–175.6 Ma
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Plesiosaurus in Japan.jpg
Restored skeleton in Japan
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Superorder: †Sauropterygia
Order: †Plesiosauria
Superfamily: †Plesiosauroidea
Family: †Plesiosauridae
Genus: †Plesiosaurus
Conybeare, 1821
Species: †P. dolichodeirus
Binomial name
Plesiosaurus dolichodeirus
Conybeare, 1824
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Kaprosuchus is an extinct genus of mahajangasuchid crocodyliform. It is known from a single nearly complete skull collected from the Upper Cretaceous Echkar Formation of Niger. The name means "boar crocodile" from the Greek κάπρος, kapros ("boar") and σοῦχος, souchos ("crocodile") in reference to its unusually large caniniform teeth which resemble those of a boar.[1] It has been nicknamed "BoarCroc" by Paul Sereno and Hans Larsson, who first described the genus in a monograph published in ZooKeys in 2009 along with other Saharan crocodyliformes such as Anatosuchus and Laganosuchus.[2] The type species is K. saharicus.

Contents [hide]
1 Description
2 Classification
3 Paleobiology
3.1 Diet
4 References
5 External links
Description[edit]

Cranium in dorsal (left) and ventral (right) view. Length 507 mm[1][3]
Kaprosuchus is known from a nearly complete skull 507 mm in length in which the lower jaw measured 603 mm long, whilst the entire animal is originally estimated to have been around 6 metres (19.7 ft) in length,[1][3] but later comparisons to similar crocodiles suggest a total estimated body length approximately 3.3 metres (10.8 ft).[4] It possesses three sets of tusk-like caniniform teeth that project above and below the skull, one of which in the lower jaw fits into notches in upper jaw. This type of dentition is not seen in any other known crocodyliform. Another unique characteristic of Kaprosuchus is the presence of large, rugose horns formed from the squamosal and parietal bones that project posteriorly from the skull. Smaller projections are also seen in the closely related Mahajangasuchus.

The snout of Kaprosuchus shows generalized proportions and the naris is positioned dorsally. In Kaprosuchus many teeth are hypertrophied and labiolingually (laterally) compressed, unlike those of crocodyliforms with similarly shallow snouts, which are usually subconical and of moderate length. Another difference between the skull of Kaprosuchus and those of crocodyliforms that also possess dorsoventrally compressed snouts is the great depth of the posterior portion of the skull.

In Kaprosuchus, the orbits (i.e., eye sockets) open laterally and are angled slightly forward rather than upward. The orbits turned forward suggest that there was somewhat stereoscopic vision, i.e., an overlap in the visual field of the animal.[3]

The surfaces of the premaxillae are rugose with the edges elevated above the body of the bone, suggesting that a keratinous shield would have been supported by the rugosities at the tip of the snout. Along the interpremaxillary suture, the area where the two premaxillae meet, the surface is smooth, giving the paired rugosity of the premaxillae the resemblance of a moustache in anterior view.[1]
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Titanosaurus (meaning 'titanic lizard' - named after the mythological 'Titans', deities of Ancient Greece) is a dubious genus of sauropod dinosaurs, first described by Lydekker in 1877.[1] It is known from the Maastrichtian (Upper Cretaceous) Lameta Formation of India.

Taxonomy[edit]
Titanosaurus is estimated to have grown up to 9–12 metres (30–40 ft) long and up to approximately 13 tons in weight. Wilson and Upchurch (2003) treated Titanosaurus as a nomen dubium ("dubious name") because they noted that the original Titanosaurus specimens cannot be distinguished from those of related animals.[2]

Species[edit]

T. blanfordi holotype distal caudal vertebra ((GSI 2195)
As the type genus of Titanosauria, Titanosaurus at times became a wastebasket genus for a number of titanosaurs, including those not just from India but also southern Europe, Laos, and South America. Only two among these, however, are currently considered species of Titanosaurus: T. indicus and T. blandfordi, both of which are considered nomina dubia.

Other species formerly referred to this genus include:

"Titanosaurus" rahioliensis - Described based on teeth, this species is now considered an indeterminate neosauropod.[2]
"Titanosaurus" colberti - This species was the most well-known species of Titanosaurus, but has been moved into its own genus, Isisaurus.[2][3]
"Titanosaurus" australis - Known from relatively complete remains, but has been renamed Neuquensaurus.[2]
"Titanosaurus" nanus - A small species found to be non diagnostic, and hence a nomen dubium.[2]
"Titanosaurus" robustus - Now referred to Neuquensaurus.[2]
"Titanosaurus" madagascariensis - nomen dubium; UCB 92305 apparently related to Vahiny, while UCM 92829 has been re-assigned to Rapetosaurus.[2]
"Titanosaurus" falloti - This large species, native to Laos, has disputed affinities. It has been considered synonymous with Tangvayosaurus and Huabeisaurus, but the remains are too fragmentary to be sure.[2][4][5]
"Titanosaurus" valdensis - Referred to a new genus, Iuticosaurus, but still considered a nomen dubium.[2]
"Titanosaurus" lydekkeri - Also referred to Iuticosaurus, but its relation to I. valdensis is uncertain.[2]
"Titanosaurus" dacus - A dwarf titanosaur; now moved to the genus Magyarosaurus.[2]
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Mosasaurus (/ˌmoʊzəˈsɔːrəs/; "lizard of the Meuse River") is a genus of mosasaurs, extinct carnivorous aquatic lizards. It existed during the Maastrichtian age of the late Cretaceous period, between about 70 and 66 million years ago, in western Europe and North America. The name means "Meuse lizard", as the first specimen was found near the Meuse River (Latin Mosa + Greek sauros lizard).Mosasaurus was among the last of the mosasaurids, and among the largest. As with most mosasaurids, the legs and feet of Mosasaurus were modified into flippers, and the front flippers were larger than the hind flippers. The largest known species, M. hoffmannii reached lengths up to 17 m (56 ft),[1] slightly longer than its relatives Tylosaurus and Hainosaurus. Mosasaurus was also more robust than related mosasaurids. The skull was more robust than in other mosasaurids, and the lower jaws (mandibles) attached very tightly to the skull. They had deep, barrel-shaped bodies, and with their fairly large eyes, poor binocular vision, and poorly developed olfactory bulbs, experts believe that Mosasaurus lived near the ocean surface, where they preyed on fish, turtles, ammonites, smaller mosasaurs, birds, pterosaurs, and plesiosaurs. Although they were able to dive, they evidently did not venture into deeper waters.

The skull of Mosasaurus tapered off into a short, conical tip. The jaws were armed with massive conical teeth. Their paddle-like limbs had five digits in front and four in back. The body ended in a strong tail, which other mosasaurid fossils suggest had a fluke similar to those of sharks and some ichthyosaurs. The body probably remained stiff to reduce drag through the water, while the end of the tail provided strong propulsion.
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Spinosaurus (meaning "spine lizard") is a genus of theropod dinosaur that lived in what now is North Africa, during the lower Albian to lower Cenomanian stages of the Cretaceous period, about 112 to 97 million years ago. This genus was known first from Egyptian remains discovered in 1912 and described by German paleontologist Ernst Stromer in 1915. The original remains were destroyed in World War II, but additional material has come to light in recent years. It is unclear whether one or two species are represented in the fossils reported in the scientific literature. The best known species is S. aegyptiacus from Egypt, although a potential second species, S. maroccanus, has been recovered from Morocco.

Spinosaurus was among the largest of all known carnivorous dinosaurs, possibly larger than Tyrannosaurus and Giganotosaurus. Estimates published in 2005, 2007, and 2008 suggested that it was between 12.6–18 metres (41–59 ft) in length and 7 to 20.9 tonnes (7.7 to 23.0 short tons) in weight.[1][2][3] A new estimate published in 2014 and based on a more complete specimen, supported the earlier research, finding that Spinosaurus could reach lengths greater than 15 m (49 ft).[4] The skull of Spinosaurus was long and narrow, similar to that of a modern crocodilian. Spinosaurus is known to have eaten fish, and most scientists believe that it hunted both terrestrial and aquatic prey; evidence suggests that it lived both on land and in water as a modern crocodilian does. The distinctive spines of Spinosaurus, which were long extensions of the vertebrae, grew to at least 1.65 meters (5.4 ft) long and were likely to have had skin connecting them, forming a sail-like structure, although some authors have suggested that the spines were covered in fat and formed a hump. Multiple functions have been put forward for this structure, including thermoregulation and display.

Contents [hide]
1 Description
1.1 Neural spines
1.2 Skull
2 Discovery and naming
2.1 Naming of species
2.2 Specimens
2.2.1 Possible specimens
3 Classification
4 Paleobiology
4.1 Function of neural spines
4.2 Diet
4.3 Posture
5 Paleoecology
6 In popular culture
7 References
8 Further reading
9 External links
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