Glossary M
Homepage > Glossary M
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 herbivore (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
This era began around 250 million years ago and ended 65 million years
ago. The major periods in this era were Triassic, Jurassic and Cretaceous
periods. It was a time of great tectonic activity.
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 Tyrannosaurus 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
Metaposaurs were medium sized, four-legged carnivorous amphibians that
lived in the Late Triassic period. They had a slab-shaped head and looked
similar to a salamander. They were up to approximately 2.75 metres long.
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
Metriorhynchus was one of the most specialised of the crocodiles being
thoroughly adapted to a marine existence with paddle-like forelimbs, a
blade-like tail and no body armour. Up to 3 metres long, it lived in the
Late Jurassic period.
MEYER, HERMANN VON
Hermann von Meyer was a German paleontologist who named and described
Archaeopteryx; (1861), Rhamphorhynchus (1847), Plateosaurus (1837), and
Stenopelix (1857).