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MARASUCHUS
(pronounced LAG-o-SOOK-us) Marasuchus (meaning: "mara [a South American
mammal] crocodile") was a dinosaur-like reptile that was an ancestor
of the dinosaurs) that lived during the middle Triassic Period, about
230 million years ago. It was about 40 cm long and may have weighed roughly
90 grams; it was light-weight, long-limbed, and had a long tail. Fossils
have been found in Talampaya National Park, Argentina. Marasuchus was
named by Sereno and Arcucci in 1994 (it was originally called Lagosuchus
lilloensis, naemd by Romer in 1972). In 1994, the paleontologist Paul
Sereno examined the type species for Lagosuchus, L. talampayensis, and
concluded that it was probably a chimera (two or more fossils jumbled
together), so Lagosuchus is considered a nomen dubium. A second species
of Lagosuchus, L. lilloensis, was then renamed Marasuchus, a new genus.
MARGINOCEPHALIA
Marginocephalians (meaning: "fringed heads") are a group of
Ornithischian (bird-hipped) dinosaurs that have a distinctive skull structure
(a slight shelf or bony frill on the back of the skull). These plant-eaters
include the ceratopsians (horned dinosaurs like Triceratops, Styracosaurus,
Pentaceratops, Protoceratops, etc.) and the Pachycephalosaurians (thick-skulled
dinosaurs like (Stegoceras, Pachycephalosaurus, etc.).
MARSH, OTHNIEL
Othniel C. Marsh (1831-1899) was a US paleontologist from Yale University
who named the dinosaur suborder Theropoda (1881), Sauropoda (1878). He
named named roughly 500 new species of fossil animals (they were found
by Marsh and his many fossil hunters). Marsh named the following dinosaur
genera: Allosaurus (1877), Ammosaurus (1890), Anchisaurus (1885), Apatosaurus
(1877), Atlantosaurus (1877), Barosaurus (1890), Camptosaurus (1885),
Ceratops (1888), Ceratosaurus (1884), Claosaurus (1890), Coelurus (1879),
Creosaurus (1878), Diplodocus (1878), Diracodon (1881), Dryosaurus (1894),
Dryptosaurus (1877), Labrosaurus (1896), Laosaurus (1878), Nanosaurus
(1877), Nodosaurus (1889), Ornithomimus (1890), Pleurocoelus (1891), Priconodon
(1888), Stegosaurus (1877), Torosaurus (1891), Triceratops (1889), Tripriodon
(1889). He named the suborders Ceratopsia (1890), Ceratosauria (1884),
Ornithopoda (1881), Stegosauria (1877), and Theropoda. He named the families
Allosauridae (1878), Anchisauridae (1885), Camptosauridae (1885), Ceratopsidae
(1890), Ceratosauridae, Coeluridae, Diplodocidae (1884), Dryptosauridae,
Nodosauridae (1890), Ornithomimidae (1890), Plateosauridae (1895), and
Stegosauridae (1880). He also named many individual species of dinosaurs.
The dinosaur Othnielia was named in 1977 by P. Galton as a tribute to
Marsh, as was Marshosaurus bicentesmus (Madsen, 1976).
MARSHOSAURUS
(pronounced MARSH-oh-SAWR-us) Marshosaurus (meaning: "Othniel Marsh'c
lizard") was a 16 ft (5 m) long meat-eating dinosaur that lived during
the late Jurassic Period, about 151-142 million years ago. Fossils of
this theropod have been found in Utah and Colorado (USA). The type species
is M. bicentisimus. Majungasaurus was named by Madsen in 1976.
Marsupial
A group of mammals characterised by premature birth and continued development
while suckling in a pouch. The group takes its name from the marsupium
or pouch - a fold of skin covering the nipples. Living examples include
kangaroos, opossums and koalas.
MASIAKASAURUS
(pronounced mah-SHEE-ah-kah-SAWR-us) Masiakasaurus (meaning: "vicious
lizard") was a meat-eating dinosaur that lived during the late Cretaceous
period. This theropod was about 6 feet 2 m) long. Fossils have been found
in Madagascar, an island off southeastern Africa. Masiakasaurus was named
by Sampson, Carrano, and Forster in 2001. The type species is M. knopfleri
(is was named for Mark Knopfler, a member of the rock band called Dire
Straits, whose music was playing at the time of discovery).
MASON, RUTH
Ruth Mason ( -1990) found a huge dinosaur fossils bone bed (a collection
of thousands of fossils) on her family's Harding County, South Dakota,
USA, ranch when she was 7 years old. Since then, tens of thousands of
dinosaur fossils have been found at the "Ruth Mason Quarry,"
near Faith, SD. The dinosaurs include huge numbers of Edmontosaurus annectens
( duck-billed, plant-eating dinosaurs), Tyrannosaurus rex teeth, and others.
MASSETOGNATHUS
Massetognathus was a genus of mammal-like reptiles from the middle Triassic
Period. This quadruped was about 19 inches (48 cm) long; it had dog-like
teeth, a long snout, clawed feet, a long tail, and it may have had hair.
Fossils of thie herbivore (plant-eater) have been found in Argentina,
South America. Classification: Subclass Synapsida, Order Therapsida, Suborder
Cynodontia, Family Tritylodontidae, Genus Massetognathus.
MASS EXTINCTION
Mass extinction is the process in which huge numbers of species die out
suddenly. The dinosaurs (and many other species) went extinct during the
K-T extinction, probably because of an asteroid that hit the Earth.
MASSOSPONDYLUS
(pronounced mass-oh-SPON-duh-lus) Massospondylus (meaning: "elongated
vertebra" ) was an herbivore dinosaur from the early Jurassic Period,
about 205-194 million years ago. This Plateosaurid sauropodomorph (an
early saurischian or lizard-hipped dinosaur) was about 13 feet (4 m) long
and 3 feet (1 m) tall. Massospondylus was named by paleontologist Richard
Owen in 1854. Massospondylus fossils have been found in Africa (in Namibia,
Zimbabwe and South Africa) and North America (in Arizona).
MASTODON
(pronounced MAST-oh-don) Mastodons (meaning: "breast tooth")
were large, elephant-like, herbivore mammals that had long tusks, grinding
molars, and a long, prehensile proboscis (nose). They evolved during the
Oligocene epoch and are closely related to mammoths and elephants. Most
mastodons lived until about 10,000 years ago, when the last Ice Age was
ending.
MAXILLA
The Maxilla (the plural is maxillae) is the upper jaw.
McINTOSH, JACK
Dr. Jack McIntosh is currently the foremost expert on sauropods. McIntosh
corrected the naming of many sauropods originally named by O.C. Marsh
and E.D. Cope. McIntosh has also done much to popularize the use of the
name Apatosaurus (rather than Brontosaurus). His most important contribution
to paleontology was identifying the correct skull for Apatosaurus in 1975
(fifty years earlier, Marsh had put a Camarasaurus skull on the Apatosaurus'
body).
MEAT EATER
Meat eating organisms are also called carnivores. They usually have sharp
teeth and powerful jaws. Some dinosaurs, like Tyrannosaurus 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
A large heavily-built, carnivorous theropod from the Middle Jurassic period.
The name has been used for many rather fragmentary remains, which may
in fact come from different theropod species.
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.