ZoomDinosaurs.com Dinosaur and Paleontology Dictionary

MEAT EATER Meat eating organisms are also called carnivores. They usually have sharp teeth and powerful jaws. Some dinosaurs, like T. rex and Velociraptor, were meat-eaters. There are fewer meat-eaters than there are plant-eaters/

MEGACEROS Megaceros (=Megaloceros) giganteus (meaning "gigantic large horn"), is the prehistoric Irish elk (more closely related to the fallow deer than the elk). It was the biggest deer that ever lived; it was over 10 feet (3 m) tall and had enormous antlers 11 feet (3.3 m) across (the largest of any deer). These antlers were shed yearly. Megaceros dates from the late Pleistocene (from 1.5 million to 2,500 years ago). Large herds of these mammals lived in what is now Europe and western Asia. It was preyed upon by giant cats and wolves and it was hunted by early humans. Class Mammalia, order Artiodactyla, family Cervidae.

MEGACERVIXOSAURUS (pronounced MEG-uh-SIR-vix-uh-SAWR-us) Megacervixosaurus (meaning "giant neck lizard") was a large, plant-eating dinosaur from the late Cretaceous period, about 97.5-65 million years ago. It had a long neck, a small head, a bulky body and a long, whip-like tail. Fossils of this diplodocid Sauropod were found in China. The type species is M. tibetensis. Megacervixosaurus was named by the paleontologist Zhao Xijin in 1983. Megacervixosaurus is a dubious genus.

MEGACHOERUS Megachoerus was a huge, warthog-like hoofed mammal that lived during the Oligocene, roughly 30 million years ago. This omnivore (it ate plants and meat) had a long skull, a small braincase, a pair of knob-like protrusions on the back of the lower jaw (in the cheek area), blunt incisors, and wide, strong canine teeth. Its long legs probably made it a fast runner. The neck was short and stout and there was a hump on the shoulders. Fossils of this Entelodont have been found in western North America (including Battle Creek, South Dakota, USA). Classification: Class Mammalia (mammals), Order Artiodactyla (even-toed ungulates), Family Entelodontidae (large, pig-like mammals from the Oligocene to early Miocene, including Archaeotherium, Megachoerus, Dinohyus, Entelodon and Eoentelodon), Genus Megachoerus. The type species is Megachoerus latidens.

MEGADACTYLUS (pronounced MEG-uh-DAK-ti-lus) Megadactylus (meaning "giant finger") is an invalid name for the plant-eating dinosaur Anchisaurus. Megadactylus was named by Hitchcock in 1865.

MEGALANCOSAURUS Megalancosaurus was a reptile (a prolacertiform archosauromorph, not a dinosaur) from the late Triassic period. It had opposable digits and a prehensile tail, which is why it is thought to have been arboreal (living in trees). It also had a pointed snout. The Megalancosaurus hypothesis (that Megalancosaurus was the ancestor of birds) is one of the theories about the origin of birds. The bird-dinosaur theory is much stronger and more widely accepted.

MEGALANIA Megalania prisca is a the largest-known terrestrial lizard (Megalania was not a dinosaur; it lived millions of years after the dinosaurs died and is a relative of the modern-day Komodo Dragon). This Australian reptile lived during the Pleistocene (roughly 26,000-19,000 years ago). A varanid lizard, it was up to 20 ft (6 m) long and may have weighed over 1,300 pounds (600 kg). This half-ton meat-eater probably ate rhinoceros-sized diprotodont marsupials. This lizard's deadly teeth were almost an inch (2 cm) long and were curved with a serrated rear edge; they could disembowel a large animal with ease. Megalania coexisted with early man in Australia, and may have included people in its diet. Classification: Order Squamata, Family Varanidae, Genus Megalania, Species prisca (named by paleontologist Richard Owen, 1860).

MEGALOCEROS Megaloceros (=Megaceros) giganteus (meaning "gigantic large horn"), is the prehistoric Irish elk (more closely related to the fallow deer than the elk). It was the biggest deer that ever lived; it was over 10 feet (3 m) tall and had enormous antlers 11 feet (3.3 m) across (the largest of any deer). These antlers were shed yearly. Megaceros dates from the late Pleistocene (from about 1.5 million to 11,000 years ago). Large herds of these mammals lived in what is now Europe and western Asia. It was preyed upon by giant cats and wolves and it was hunted by early humans. Class Mammalia, order Artiodactyla, family Cervidae.

MEGALODON Carcharodon/Carcharocles megalodon was an ancient shark, living between 5-1.6 million years ago; it is extinct. It may have been up to 40 feet (12 m) long.

MEGALOSAURIPUS (pronounced MEG-ah-lo-SAWR-uh-pus) Megalosauripus (meaning "great lizard foot") is a dinosaur which is known only from its fossilized, three-toed footprints; it is an ichnogenus. Megalosauripus tracks are the footprints of a Megalosaur (hence its name) from the late Jurassic period. Fossilized footprints have been found in Asia, Europe, and North America, Megalosaurs were meat-eating bipeds (theropods).

MEGANEURA Meganeura monyi was an ancient dragonfly that lived about 280 million years ago. This flying predator was the biggest insect that ever lived - it had a wingspan of about 2 feet.

MEGALOSAURUS (pronounced MEG-ah-lo-SAWR-us) Megalosaurus (meaning "great lizard") was a large dinosaur that lived during the Jurassic period. This bipedal meat-eater was up to about 26 ft (8 m) long. Fossils have been found in England and France. Megalosaurus was named by Wm. Buckland in 1824 (it was found by workers in an Oxfordshire, England limestone quarry and is now lost). The type species is M. bucklandii.

MEGANTEREON Megantereon was an early sabertooth cat. This mammal was about 4 ft (1.2 m) long and had two dagger-like teeth. This carnivore lived from the late Miocene to the early Pleistocene, roughly 2-3 million years ago, in South Africa, India, USA (Texas) and France. Megantereon used its large teeth to prey upon large, thick-skinned mammals, like the mastodont.

MEGARAPTOR (pronounced meg-ah-RAP-tor) Megaraptor (meaning "Huge robber") is a newly discovered, 90 million year old dinosaur that had a 14 inch (34 cm) long sickle-like claw on the second toe of each long, thin foot. When alive, this claw would have been sheathed in a horny, keratinous material much like our fingernails, making the claw even bigger, longer and sharper. This bipedal meat-eater was about 26 feet (8 m) long. It was more primitive than the Dromaeosaurids (the true raptors) which had wider feet. Megaraptor was a theropod, a tetanuraen, and a coelurosaurid. A very incomplete skeleton (including a sickle-like claw, metatarsal, ulna, and a finger bone) was discovered in 1996 by paleontologist Fernando Novas in Northwest Patagonia, Argentina, South America. Some scientists believe that Megaraptor is actually an adult Unenlagia.

MEGATHERIUM (pronounced MEG-ah-THEER-ee-um) Megatherium was the largest giant ground sloth; its name means "great beast." Megatherium was a huge, bulky, slow-moving herbivore (plant-eater) with peg-like teeth, powerful jaws, and a thick, short tail. This ice-age mammal had three hook-like claws on each hand. It was primarily a quadruped (walked on four legs). It may have eaten leaves from the tops of trees while standing upright on its hind legs, using its tail to balance. Megatherium was the size of an elephant. It lived during the Pleistocene epoch in what is now South America, going extinct about 11,000 years ago. It was about 20 feet (6 m) long and weighed roughly 3-4 tons. Megatherium was named by R. Owen in 1856; the first Megatherium fossil was found in Brazil in 1789. (Cohort (many grouped orders) Edentata, Family Megatheriidae, Genus Megatherium.)

MEGAZOSTRODON Megazostrodon was one of the earliest mammals. It was a tiny quadruped with a long tail, a long body, and a long snout. It lived from the late Triassic period through the early Jurassic period. This primitive mammal was about 4 inches (10 cm) long and weighed only a few ounces. It may have eaten insects. A complete fossilized skeleton was found in Lesotho, South Africa.

MEGISTOTHERIUM Megistotherium was a huge Hyaenodont (not a dinosaur, but an early, hyena-like mammal, a creodont) from the Miocene Epoch (about 24 million years ago). This meat-eater may have been a scavenger and/or an active hunter. Its skull was over 3 ft (1 m) long. Fossils have been found in northern Africa (Egypt and Libya). Megistotherium was named by Robert J. G. Savage in 1973. Classification: Superorder Ferae, Order Creodonta, Family Hyaenodont.

MELANOROSAURUS (pronounced muh-LAN-or-oh-SAWR-us) Melanorosaurus (meaning "black mountain lizard") was a large, heavy prosauropod, an early plant-eating saurischian dinosaur. It lived during the late Triassic period, about 228 to 219 million years ago. It walked on four sturdy legs, was about 40 feet (12 m) long, had a long neck, long tail, thick bones, a bulky body, five-toed feet, and a small head. Its rear legs were longer than its front legs. Its fossils have been found in South Africa. Melanorosaurus was named in 1924 by the British paleontologist Sydney H. Haughton.

MERYCHIPPUS Merychippus (meaning "ruminant horse") is an extinct, three-toed horse about the size of a pony with a long, horse-like face. It was about 6.5 feet (2 m) long and was roughly 3 feet (1 m) tall at the shoulder. Its middle toe had a well-developed hoof (earlier horses had only toes and no hoof) and supported all its weight. It lived during the Miocene to the Pliocene (about 26 to 7 million years ago) in the grasslands of North America. It had tall-crowned teeth that could grind grass well; it was the earliest horse that ate grass exclusively, hence its name. Classification: Order Perissodactyla, Family Equidae. This genus was named by Joseph Leidy.

MERYCOICOCON Merycoidodon was an oreodont, a (meaning "mountain tooth") were the most common hoofed herbivorous (plant-eating) mammal that lived in North America during the Oligocene (from about 35-5 million years ago). Merycoidodon was a quadrupedal ruminants closely related to camels, pigs, and sheep. The skull was elongated and the upper canines were chisel shaped; the cheek teeth were used for grinding. It was 4.5 ft long. Fossils have been foud in South Dakota. Classification: Class Mammalia (mammals), Order Artiodactyla (even-toed ungulates), Suborder Tylopoda (padded feet - oreodonts, camels), Family Merycoidodontidae, Genus Merycoidodon, many species - the type species is Merycoidodon culbertsonii (Leidy, 1848). Merycoidodon was named by Joseph Leidy in 1848.

MESOHIPPUS Mesohippus (meaning "middle horse") is an extinct, dog-sized, three-toed horse. It was about 4 feet (1.2 m) long and was roughly 2 feet (60 cm) tall at the shoulder. Its middle toe had a light-weight hoof wth a large, weight-supporting middle toe; the head was long and pointed (the jaws were shallow). Mesohippus lived during the middle Oligocene (about 37-32 million years ago) in the Great Plains and foothills of the Rockies of North America. It had low-crowned teeth that could grind relatively well; its premolars were beinning to resemble its molars. Mesohippus' diet consisted of leaves from shrubs and low trees. Classification: Order Perissodactyla, Family Equidae.

MESOSAURUS (pronounced MESS-oh-SAWR-us) Mesosaurus (meaning "middle lizard") was an odd, fresh-water dwelling reptile (not a dinosaur) that lived from the late Carboniferous period to the early Permian period. It was a lightly-built, four-legged animal with an elongated head and snout with nostrils near its eyes. It had a flattened tail that was probably used for swimming. It was about 1.5 feet (45 cm) long. This carnivore probably ate fish and shrimp, catching them with its mouth. It was a primitive reptile that returned to the water about 300 million years ago after having adapted to the land; Mesosaurus was one of the first aquatic reptiles. Fossils have been found in South Africa and South America, reinforcing Wegener's theory of continental drift.

MESOZOIC ERA The Mesozoic Era ("The Age of Reptiles"), occurred from 248-65 million years ago. It is divided into the Triassic, Jurassic, and Cretaceous periods. Dinosaurs, mammals, and flowering plants evolved during the Mesozoic, and Pangaea broke up. The era ended with the K-T mass extinction. The term Mesozoic (meaning "middle animal") was coined by John Phillips in 1840.

METABOLIC DISEASE Metabolic diseases, like gout or diabetes, are diseases in which the body produces a metabolic imbalance (chemical or physical), like too much uric acid in gout, or an inability to metabolize carbohydrates properly in diabetes. These diseases are not contagious, but occur in congenitally predisposed individuals. Some fossilized T. rex bones have shown evidence of gout.

METACARPALS Metacarpals are the bones of the palm, between the wrist (carpals) and the fingers (phalanges).

METATARSALS Metacarpals are the bones of the upper part of the foot, between the ankle (tarsals) and the toes (phalanges).

METAMORPHIC ROCK Metamorphic rocks are compacted by pressure and heat from deep inside the earth.

METEOR A meteor is a meteoroid that has entered the Earth's atmosphere, usually making a fiery trail as it falls. It is sometimes called a shooting star. Most burn up before hitting the Earth.

METEORITE A meteorite is a meteor that has fallen to Earth. Meteorites are either stone, iron, or stony-iron.

METEOROID Meteoroids are tiny stones or pieces of metal that travel through space.

METOPOSAUR pronounced me-TOP-oh-sores) Metoposaurs were huge, primitive amphibians (they were not dinosaurs). Metoposaurs had a large, flattened, shovel-shaped head, very big jaws, four short legs with four-toed feet, a powerful tail, arch-shaped vertebrae, and a stocky body. Unlike many earlier amphibians, Metoposaurs had an otic notch, an opening behind each eye that was covered with a taut membrane; these structures detected sounds. They were roughly 8 ft (2.5) long. These carnivores lived close to the water, where they laid their shell-less eggs. The inside of the sharp teeth had infolded tooth enamel and notable crinkly rings; they also had fangs. Fossils of these tetrapods date from the late Triassic period have been found in North America. An example of a metoposaur was Buettneria. Metoposaurids were Labyrinthodonts (advanced Temnospondyls).

METRIACANTHOSAURUS (pronounced MET-ri-ah-CAN-thuh-SAWR-us) Metriacanthosaurus (meaning "moderate-spined lizard") was a theropod dinosaur from the late Jurassic period, about 160 million years ago. This large, bipedal meat-eater was about 26 ft (8 m) long and weighed about 1 ton. It had high spines, about 10 inches (25 cm) long, on its dorsal (back) vertebrae. These spines were twice as long as the vertebrae themselves; they may have given this dinosaur a hunch-backed appearance. An incompete fossil was found in England. The type species is M. parkeri. Metriacanthosaurus was namd by Walker in 1964.

METRIORHYNCHUS (pronounced MET-ri-oh-RINK-us) Metriorhynchus (meaning "moderate snout") was a crocodilian, an aquatic reptile that was up to 40 feet (12 m) long. It had a long, toothed snout, a fish-like tail, and four short limbs with webbed feet. The rear legs were longer than the front legs. Metriorhynchus had no back armor. It lived during the mid to late Jurassic period. Fossils have been found in Europe (France and England) and South America (Chile). Classification: Order Crococylia, Suborder Mesosuchia, Genus Metriorhynchus, many species.

MEYER, HERMANN VON Hermann von Meyer was a German paleontologist who named and described Archaeopteryx; (1861), Rhamphorhynchus (1847), Plateosaurus (1837), and Stenopelix (1857).

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