Page 72 - Dinosaur (DK Eyewitness Books)

Glossary

AMMONITES CERATOPSIANS (“horned faces“)
An extinct group of mollusks related to squid; Bipedal and quadrupedal, plant-eating
with a coiled shell. They lived in Mesozoic seas. ornithischians, with a deep beak and a
bony frill at the back of the skull. Many,
AMPHIBIANS such as Triceratops, had facial horns.
A group of cold-blooded vertebrates (backboned
animals) originating more than 100 million years CO/'͆B/OO'E'
before the dinosaurs. The young live in fresh Animals that are cold-blooded (or more properly,
water but many transform into land-based adults. ectothermic), are dependent upon the Sun’s heat Mammal (Negabaata)
Living amphibians include frogs and salamanders. for body warmth. Most reptiles are cold-blooded
(see also WARM-BLOODED). well adapted to their environment produce more
ANGIOSPERMS offspring than those less well adapted, and pass
Flowering plants—one of the two main types CONIFER on more genes to future generations). When
of land plant that produce seeds (see also Cone-bearing tree such as a pine or fir. populations become separated, they begin
GYMNOSPERMS). Angiosperm seeds are evolving independently in different directions,
enclosed by an ovary, which later develops into COPROLITE and new species emerge. Dinosaurs gradually
a fruit. Flowering plants first appeared in the Fossilized dung. evolved from reptile ancestors, and birds evolved,
Cretaceous Period and eventually transformed step-by-step, from dinosaurs.
dinosaur habitats. Angiosperms range from CRETACEOUS PERIOD
grasses and herbs to great broadleaved trees, and Third period of the Mesozoic Era; about EXTINCTION
include kinds such as magnolias that have 145–65 million years ago. The dying-out of a plant or animal species.
changed little since the Cretaceous.
CYCAD FOSSIL
Palm-shaped, seed-bearing plant The remains of something that once lived,
with long, fernlike leaves. A type of preserved in rock. Teeth and bones are more
gymnosperm. Cycads were common likely to form fossils than softer body parts,
during the Age of Dinosaurs. such as internal organs.
DROMAEOSAURIDS (“running lizards”) GASTROLITH
A group of birdlike theropods that were closely Any stone swallowed by an animal to help
related to birds. grind up food in the stomach.
DUC.͆BILLED DINOSAURS GENUS (plural, GENERA)
See HADROSAURS In the classification of living organisms, a
group of closely related species. The species
EMBRYO Tyrannosaurus rex is grouped with related
Bipedal (Giganotosaurus) A plant, animal, or other organism in an early species into the genus Tyrannosaurus.
stage of development, before germination,
ANKYLOSAURS (“fused lizards”) hatching, or birth. GINKGO
A group of four-legged, armored, plant-eating A unique type of broadleaved tree that evolved
ornithischians with bony plates covering the EVOLUTION in the Triassic Period and survives essentially
neck, shoulders, and back, and a horny beak The gradual changes in living organisms that unchanged to this day. A type of gymnosperm.
used for cropping plants. occur over many generations, controlled mainly
by the process of natural selection (organisms GYMNOSPERMS
ARCHOSAURS One of the two main types of land plant that
A broad group of extinct and living reptiles produce seeds. It includes cycads, ginkgos, and
with two main subgroups. Crocodiles and their conifers, such as pine and fir. Gymnosperms
relatives form one group. Dinosaurs, pterosaurs, produce naked seeds.
and their relatives form the other.
HADROSAURS (“bulky lizards”)
ASTEROID Duck-billed dinosaurs. Large, bipedal
A rocky lump orbiting the Sun. Asteroids and quadrupedal ornithopods from
are smaller than planets but can measure late in the Cretaceous Period. They
hundreds of miles across. had a ducklike beak that was used
for browsing on vegetation.
BIPEDAL
Walking on two hind limbs, rather than HERBIVORES
on all fours. Animals that feed on plants.

BIRDS ICHTHYOSAURS
A group of dinosaurs with feathered Large prehistoric reptiles with a pointed
wings. Some scientists call the whole head, flippers, and a tail like a fish’s. Ichthyosaurs
group Aves. Others call the modern birds Aves were streamlined for swimming fast in the sea.
or Neornithes, and refer to the extinct, primitive Most lived in the Jurassic Period.
birds as Avialae.
JURASSIC PERIOD
CARNIVORES Second period of the Mesozoic Era; about
Animals that feed on meat. 200–145 million years ago.
CARNOSAURS MAMMALS
Large theropods with a big skull and teeth. Once Warm-blooded, hairy vertebrates that suckle
used for all such meat-eaters, the name is now their young. Mammals began to appear in the
restricted to Allosaurus and some of its relatives. Cycad Triassic Period.

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