Page 12 - Reptiles & Dinosaurs (Britannica Illustrated Science Library)

8 DINOSAURS REPTILES AND DINOSAURS 9

Terrible Lizards Marsh vs. Cope

SIR DINOSAUR
The American paleontologists accusations of espionage, fraud, theft, Sir Richard Owen, a British
inosaurs dominated the Earth for 170 million years, from the late Othniel C. Marsh and Edward and even personal violence. Marsh paleontologist, was the first to identify
Triassic to the late Cretaceous periods, when the supercontinents of D. Cope faced off in a very peculiar considered himself the winner of fossil remains of “terrible lizards,” or
struggle. They competed to determine
“Bone Wars,” but the field of
“monstrous lizards.” He proposed the
D Laurasia and Gondwana were splitting into the landmasses of today. who could find more dinosaur bones paleontology was the real winner as term Dinosauria, based on his studies
The mass extinction of the dinosaurs about 65 million years ago left fossil and species. The competition was roughly 130 species were identified and discoveries, and made the first
between the two rivals.
plagued with corruption, mutual
reconstruction of a fossil for the great
remains, including footprints, eggs, and bones. Finding these fossils has London Exhibition of 1851.
enabled scientists to study and classify dinosaurs and to learn about
their posture, size, diet, and many other aspects of their lives. These Flexible Neck
studies revealed that this prehistoric group of lizards included Moved more Saurischians FIERCE LIZARDS SUBORDER INFRAORDER
herbivores and carnivores of extraordinary size and striking shapes. easily because the These dinosaurs had hip Carnivores of the Cretaceous Period. Ceratosauria
vertebrae were
They grew up to 46 feet (14 m) long
Coelophysis
light in weight bones similar to those of and weighed up to 7.7 tons (7 metric bauri
today's reptiles, such as tons). Their teeth were like knives. Theropoda
crocodiles and lizards. Many Tetanurae
species of saurischian dinosaurs Allosaurus
Legs have been found, including fragilis
Velociraptor and
Depending on their lifestyle, posture. Due to the structure of their Argentinosaurus. They had long,
some dinosaurs walked on two legs, they bear little resemblance to DEINOS SAURO flexible necks and large claws
legs, and some walked on four. their relatives today: lizards, tuataras, Terrible Lizard on the initial digits. Prosauropoda
However, they all had a similar turtles, snakes, and crocodiles. Plateosaurus
engelhardti
IDENTITY Sauropodomorpha
The term Dinosauria was BAROSAURUS Lizard Hip Tyrannosaurus rex Sauropoda
proposed for these extinct or “heavy reptile” Pelvic structure of Argentinosaurus
LIZARDS reptiles by paleontologist saurischian dinosaurs huinculensis
1 The limbs project Richard Owen in 1842. The
outward. At the
elbows and knees, the name of each species is
based on characteristics of
legs are bent at right its shape and physiology,
angles. This the name of its discoverer, ORNITHISCHIANS SUBORDER INFRAORDER
arrangement is called or the location where it Ornithischians
extended posture. Named for the curvature in their Scelidosauria
was found. Herbivores with hip bones thighbones. They could walk on Trimucrodon
structured like those of birds. two legs. cuneatus
The pubis slants
backward, parallel to Stegosauria
the ischium. Some of Thyreophora Stegosaurus
CROCODILES the most famous armatus
2 These animals have ornithischians were Ankylosauria
Triceratops and
semi-extended posture.
The limbs project out 3 Parasaurolophus. Some Centrosaurus sp.
and down. The elbows ornithischians were
and knees are bent at a protected from head to Marginocephalia
45° angle. These species DINOSAURS tail by bony plates. Triceratops
crawl slowly and These animals had erect prorsus
straighten up to run. posture. The limbs project They Only Look Alike Cerapoda
below the body. Both the In spite of their name, these animals Euornithopoda
elbows and the knees are are not ancestors of today's birds. Camptosaurus sp. Pisanosaurus
beneath the body. mertii
tons
GOLDEN YEARS 110 (100 metric tons) Over 2,000
From the primitive dinosaurs of the Triassic carnivores dominated the landscape, living under ESTIMATED WEIGHT OF AN SPECIES OF DINOSAURS HAVE BEEN
Period, evolutionary lines of carnivores and environmental conditions that favored enormous ARGENTINOSAURUS CATALOGED AT PRESENT.
herbivores diverged. Later in the Jurassic and diversity in body forms and feeding behaviors—
Cretaceous periods large herbivores and fierce until their extinction.

Herrerasaurus Coelophysis Eoraptor Mussaurus Plateosaurus Dryosaurus Megalosaurus Brachiosaurus Stegosaurus Camarasaurus Therizinosaurus Caudipteryx Suchomimus Giganotosaurus Corythosaurus
Length: 13 feet (4 m) Length: 9.2 feet (2.8 m) Length: 3 feet (1 m) Length: 6.6 feet (2 m) Length: 26 feet (8 m) Length: 13 feet (4 m) Length: 29.5 feet (9 m) Length: 82 feet (25 m) Length: 30 feet (9 m) Length: 66 feet (20 m) Length: 39 feet (12 m) Length: 3 feet (1 m) Length: 43 feet (13 m) Length: 49 feet (15 m) Length: 33 feet (10 m)
TRIASSIC PERIOD 251-199.6 MILLION YEARS AGO JURASSIC PERIOD 199.6-145.5 MILLION YEARS AGO CRETACEOUS PERIOD 145.5-65.5 MILLION YEARS AGO