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(pronounced nah-ah-sho-ee-BEE-to-SAWR-us) Naashoibitosaurus (meaning: "Naashoibito lizard") was a plant-eating dinosaur that lived during the late Cretaceous period. This hadrosaur (duck-billed dinosaur) was about 30 ft (10 m) long. A fossil (only a skull) has been found in New Mexico, USA. Naashoibitosaurus was named by Hunt and Lucas in 1993. The type species is N. ostromi. Naashoibitosaurus may be a variant of Kritosaurus navajovius.

A primitive, carnivorous bird that lived in the Early Cretaceous period. Nanantius was a scavenger and about the size of a present day black bird but had a pelvic structure very different from that of modern birds.

Nanofossils are microscopic fossils that are very abundant, widely distributed, and time-specific (because of their high evolutionary rates). They are very useful index fossils.

(pronounced NAN-oh-SAWR-us) Nanosaurus (meaning: "dwarf lizard") was a small bipedal plant-eater from the Jurassic Period (156-145 million years ago). It was about 4 feet long (120 cm) and 1.5 feet tall (46 cm). Nanosaurus is known from a jawbone found in western North America. Nanosaurus was an ornithischian dinosaur named by paleontologist Othniel C. Marsh in 1877.

(pronounced NAN-oh-tie-RAN-us) Nanotyrannus (meaning: "tiny tyrant") was a bipedal meat-eater, a theropod from the late Cretaceous Period (68-65 million years ago). It was about 16 feet long (5 m), had a large head, long legs with three-toed feet, short arms with two-fingered hands, a short, thick neck, large jaws with sharp teeth, narrow hips, and a slim tail. Nanotyrannus was a tyrannosaurid dinosaur named by paleontologists M. Williams, R. Bakker, and P. J. Currie in 1988 from a skull only 22 inches (57.2 cm) long found in Montana, USA in 1942. It may be a juvenile Tyrannosaurus rex. The only known skull has been CAT-scanned by Bakker. He thinks that Nanotyrannus is an adult, but many other paleontologists, like Thomas D. Carr disagree, and think the Nanotyrannus is a juvenile Tyrannosaurus rex.

Nanyangosaurus is an iguanodontid dinosaur found in the Sangping Formation of Neixiang, Henan, China. This plant-eating dinosaur lived during the Cretaceous Period. Nanyangosaurus zhugeii was named by Xu, Zing, Xi-Jin Zhao, Jun-Chang Lu, Wang-bo Huang, Zhang-Yang Li and Zhi-Ming Dong in 2000, but is unpublished.

Nares are the openings in the skull for the nostrils. (The singular of nares is naris.)

Natural selection is the process in which some organisms live and reproduce and others die before reproducing. Some life forms survive and reproduce because they are better suited to environmental pressures, ensuring that their genes are perpetuated in the gene pool.

Nautiloids are primitive, thick-shelled, carnivorous marine invertebrates, cephalopod. The shell is divided into chambers. The nautiloid head has well-developed eyes and tentacles that can grasp prey. They swim by jet-propulsion; they squirt water out from the body cavity. They evolved during the Silurian and are still around today, but are uncommon (only a single genus survives). They were most abundant during the Paleozoic Era, roughly 400 million years ago. Some Nautiloids evolved into Ammonoids.

Cephalopod molluscs that possess a smooth, coiled shell consisting of about 36 chambers. The animals live in the last chamber. They adjusts their buoyancy by flooding and expelling water from the chambers and propelled themselves by squirting water like a squid. They are active predators catching small fish with their tentacles. The Nautiloids were most abundant during the Palaeozoic Era - only a single genus survives today, in deep water in the Pacific.

(pronounced ned-kohl-BERT-ee-ah) Nedcolbertia (named to honor the paleontologist Edwin 'Ned' Harris Colbert) was a small, meat-eating dinosaur that lived during the early Cretaceous period, roughly 127 to 121 million years ago. It was a biped that walked on two long legs. It was about 10 feet (3 m) long. This coelurosaurid theropod is known from three partial skeletons (no skulls) found in the Yellow Cat Member of the Cedar Mountain Formation Utah, USA. Nedcolbertia was found by C. H. Whittle, and named by J. I. Kirkland, B. B. Britt, Whittle, S. K. Madsen, and D.L. Burge in 1998. The type species is N. justinhoffmani.

(pronounced NAY-meg-toe-SAWR-us) Nemegtosaurus was a sauropod dinosaur from the late Cretaceous Period, about 75-70 million years ago. This quadrupedal plant eater had a long neck, a long, small head with lance-like teeth, and a long tail. It was named by Nowinski (in 1971) for the Nemegt Basin in the Gobi desert of southern Mongolia, where the skull was found. The type species is N. mongoliensis. Since only the skull has been found, very little is known about this dinosaur.

(pronounced NEE-oh-sir-at-oh-SAWR-ee-ah) Neoceratosauria (meaning: "new horned lizards") was a group of small to medium-sized meat-eating dinosaurs, most of which had horns on their head. Neoceratosaurs had four fingers on each hand and a bipedal (two-legged) walk. These theropods lived during in Gondwana (the southern continent, which included South America, Africa, India, Australia, and Antarctica) during the early Jurassic Period through the Cretaceous Period, roughly 180-71 million years ago. The clade Neoceratosauria was named by paleontologists F. Novas in 1991. Some Neoceratosaurs include Ceratosaurus (pictured above), Carnotaurus, Majungatholis, Indosuchus, and many others.

The Neocomian epoch was the early (lower) part of the Cretaceous Period, about 144 to 127 million years ago.

The Neogene (24 million to 1.8 million years ago) was the later part of the Tertiary Period. It is divided into the Miocene Epoch (24 million to 5 million years ago, when many mammals appeared, including the horses, dogs, bears, South American monkeys, apes in southern Europe, and Ramapithecus; also, modern birds appear) and the Pliocene Epoch (5 million to 1.8 million years ago, when the first hominids (australopithecines) developed, modern forms of whales appeared, and Megalodon swam the seas).

The Neognathae (meaning: "new jaw") are birds . They include most flying birds plus swimming and diving birds like penguins. Neognaths evolved during the Late Cretaceous Period, about 70 million years ago. They are grouped together taxonomically based on palate (jaw) structure. (Compare to Palaeognathae.)

Neornithes (meaning: "new bird") is the clade of modern birdsthat have feathers, a beak covered in horn, and a four-chambered heart. This clade includes the recent common ancestor of modern-day birds and all of the descendants.

Neoteny (meaning: "new stretch") is a method of reproduction in which the an offspring is produced while an organism is still in, or maintains many characteristics of, its larval or juvenile stage. Salamanders exhibit neoteny; they maintain gills and other larval features when they are reproductively mature. Neoteny is also known as pedogenesis or paedogenesis.

(pronounced NEE-oh-ven-AY-tor) Neovenator (meaning: "new hunter") salerii, a 24.5-26 ft (7.5-8 m) long early Cretaceous theropod similar to (but smaller than) Allosaurus was found on the Isle of Wight. It was named by paleontologists Hutt, Martill and Barker in 1996.

Elizabeth (Betsy) L. Nicholls is a paleontologist and the Curator of Vertebrates at the Royal Tyrrell Museum, Alberta, Canada. Dr. Nicholls studies Triassic period marine reptiles (especially Ichthyosaurs) from North America. Nicholls received her Ph.D. from the University of Calgary, Canada. Nicholls and Jack M. Callaway are the editors of the book, "Ancient Marine Reptiles," 1997. Nicholls has named the ichthyosaur genera Metashastasaurus (Nicholls and Makoto Manabe, 2001) and Parvinatator (Nicholls and Brinkman, 1995).

(pronounced nee-ZHAER-SAWR-us) Nigersaurus was a primtive, long-necked, plant-eating dinosaur from the early Cretaceous Period, about 135 million years ago. This sauropod was about 49 feet (15 m) long and had 600 teeth in its wide mouth. Nigersaurus was excavated by a team of paleontologists led by Paul Sereno. It was named in 1999 by Sereno, Beck, Dutheil, Larsson, Lyon, Moussa, Sadler, Sidor, Varricchio, G. P. Wilson and J. A. Wilson. Fossils were found in the Sahara desert in Niger, Africa. The type species is N. taqueti.

(pronounced ni-PON-oh-SAWR-us) Nipponosaurus (meaning: "Japanese lizard") was a small, duck-billed dinosaur from the late Cretaceous Period, about 88-86 million years ago. This bipedal plant eater had a small, bony head crest, a short neck, a long, a toothless beak, and a stiff tail. Fossils of this alambeosaurine hadrosaur were found ion Sakhalin Island. Nipponosaurus was named by Nagao in 1936. The type species is N. sachalinensis. Nipponosaurus may be tha same as Jaxartosaurus.

(pronounced NOH-ah-SAWR-us) Noasaurus (meaning: "N.O.A. [= Northwestern Argentina] lizard") was a small, meat-eating dinosaur from the late Cretaceous Period, about 75 to 65 million years ago. This noasaurid theropod was about 6 ft (1.8 m) long. Noasaurus had a sickle-shaped claw on the second toe of each foot; this claw had a very wide range of movement, even wider than that of the dromaeosaurids like Deinonychus. Noasaurus is the earliest-known coelurosaur. Partial fossils were found in Argentina, South America and named by paleontologists Bonaparte and Powell in 1980. The type species is N. leali.

(pronounced NODE-oh-SAWR-ids) Nodosaurids were one division of the ankylosaurs, a group of armored, plant-eating, ornithischian dinosaurs with spikes running along the sides of their bodies, no tail clubs and pear-shaped heads. Acanthopholis, Hylaeosaurus, Minmi, Nodosaurus, Panoplosaurus, and Sauropelta were nodosaurids.

The nodosaurs were a group of four-legged, ornithsichian dinosaurs of the Cretaceous period. They were armoured with bony plates and spikes down the back and flanks but lacked the heavy tail clubs of their close relations the ankylosaurs.

A genus (or species) name is described as a nomen dubium if its classification is not certain; it does not fulfill the stringent criteria set by the International Code of Zoological Nomenclature amd mot recognized as as legal scientific name. Often, this is because there is insufficient fossil material available. For example, Acanthopholis, Altispinax, and Trachodon are dinosaur genera, each of which is described as nomen dubium.

A genus name is described as a nomen nudum if it has been insufficiently described or lacks a type species. For example, Arkansaurus, Coelurosaurus, and Likhoelesaurus are genera, each of which is described as nomen nudum.

David B. Norman is a British paleontologist who has extensively studied ornithischian clades, especially the genus Iguanodon. He noted that Iguanodon's beak structure would let it eat a wide range of plants, not simply soft plants as was thought before. He also realized that Iguanodon's tail was held horizontally, suggesting that it walked on four legs as an adult. He has also written many books about dinosaurs, including The Illustrated Encyclopedia of Dinosaurs (1985).

(pronounced NOTH-oh-sawrs) Nothosaurs were fish-eating reptiles with four flipper-like limbs. They lived both on land and in the water during the Triassic Period. These streamlined swimmers were not dinosaurs. Nothosaurs had webbed feet, and elongated bodies and necks. Nothosaurs (Order Nothosauria) includes the family Nothosauridae (Nothosaurus, Lariosaurus, and Ceresiosaurus) and the family Pistosauridae (Pistosaurus - more like a pleasiosaur).

(pronounced noth-RON-e-cus) Nothronychus (meaning: "sloth-like lizard") was a theropod dinosaur that lived during the late Cretaceous Period (94-90 million years ago). It was about 4.5 to 6 m long and may have weighed 900 kg. Nothronychus was a therizinosaur; it had a long neck and may have had feathers. Nothronychus is known from roughly half of one fossil skeleton found in New Mexico, USA, North America (this is the first found that was not from Asia). Nothronycus was found by a team of paleontologist led by Doug Wolfe (of the Mesa Southwest Museum in Mesa, Arizona, USA).

(pronounced NOTH-oh-SAWR-us) Nothosaurus was a nothosaur, a reptile with flipper-like limbs that lived both on land and in the water (like a modern-day seal). It was about 10 feet (3 m) long and had a long, thin, pointed tail with a fin on its upper portion. This tail must have been used for swimming. It had five long, webbed toes. The forelimbs were shorter than the rear limbs. The jaws were long, thin and full of pointed, interlocking teeth (good fish traps). Nothosaurus lived during the entire Triassic Period. Fossils have been found in what is now Europe (Germany, the Netherlands, and Switzerland), North Africa, and Asia (China, Israel, and Russia). It was not dinosaur, but another type of reptile. Classification: Order Nothosauria, Family Nothosauridae.

(pronounced note-oh-SER-a-tops) Notoceratops ("southern horned face") was a ceratopsian (a frilled, horned, quadrupedal, herbivore dinosaur with a beak) known only from a late Cretaceous (83-73 million years old) jaw bone. It was found in Argentina, South America, and was named by paleontologist Augusto Tapia in 1918.

Fernando E. Novas is an Argentinian paleontologist from the Museum of Natural History in Buenos Aires. He named Frenguellisaurus (1986), conamed Abelisaurus (with J. F.Bonaparte, 1985), and conamed Unenlagia (with Puerta, 1997).

Nqwebasaurus was a meat-eating dinosaur that lived during the early Cretaceous period. This coelurosaurid theropod had a very large claw on the first digit (finger). Seventy percent of a skeleton (nicknamed 'Kirky') was found in the Kirkwood Formation in the Algoa Basin, Eastern Cape, South Africa. Nqwebasaurus was named by paleontologists/geologists Billy J. de Klerk, Catherine A. Forster, S. Sampson, A. Chinsamy, and Callum F. Ross in 2000. The type species is N. thwazi. This is the first dinosaur with a click sound in its name. Nqwebasaurus thwazi (pronounced n-KWE-bah-SAWR-us TWAH-zee - to pronounce the q, pull your tongue off the roof of your mouth to produce a click on the 'q'). Nqwebasaurus means 'Nqweba lizard' - Nqweba is the Xhosa [a language similar to Zulu that is spoken by the Bantu peoples of Africa] name for the Magisterial District of Kirkwood, where this dinosaur was found. Thwazi is an old Xhosa word for a fast running messenger (an almost mythical meaning:, according to Billy de Klerk, who named Nqwebasaurus) Kirkwood is a small citrus farming village in the Sundays River valley about 30 miles (50 km) north of the coastal city of Port Elizabeth.

Nurosaurus, also called Nuoerosaurus, was a long-necked, long-tailed plant-eater (a sauropod) about 85 feet (26 m) long. Nurosaurus was named by paleontologist Dong in 1992. Fossils were found in China. The type species is N. qaganensis. This genus is a nomen nudum (it is lacking a formal description).

Nuthetes destructor was a small meat-eater from the middle Jurassic. Nuthetes was named by paleontologist Owen in 1854. Fossils were found in Europe. Owen is a dubious genus; it is probably a small Megalosaurus destructor (a theropod).