Page 39 - Reptiles & Dinosaurs (Britannica Illustrated Science Library)

34 REPTILES: BACKGROUND REPTILES AND DINOSAURS 35

The Family Tree Tough Skin Skull Types

ARMOR Scutosaurs were quadrupeds with massive The fossils of the most primitive
reptiles correspond with the Lower
he first reptiles descended from ancestral amphibians. They distinguished themselves from their Sharp points formed a legs, similar to strong columns with wide Carboniferous Period. These reptiles were
bases, which sustained the weight of their
protective armor
ancestors through mutations that allowed them to free themselves from their dependence against predators. bodies. These reptiles belonged to the extinct terrestrial animals, somewhat similar to
genus Scutosaurus species. They were large
T on water for reproduction. Among these adaptations, the amniotic egg stands out, but herbivores that lumbered through the pines Weight 1,100 the Mesozoic reptiles. The diapsid lineage
originated with them.
and firs of Permian forests in search of food,
equally important were the development of sex organs that favored internal copulation, an such as herbs and soft buds. pounds (500 kg)
8 feet
impermeable skin, and the formation of a low volume of urine that eliminates uric acid (2.5 m)
instead of urea. These adaptations to its environment were necessary to the reptilian SHIELD LIZARD
dominance of the greater part of the Mesozoic Era. Scientific Name Scutosaurus sp.
Diet Herbivore
Habitat Land
Location Europe (Russia)
ANAPSID
Era End of Permian A group of reptiles without openings in the
REPTILE Ichthyosaurs Metriorhynchus skull near the temples. This is the condition
EVOLUTION seen in fish, amphibians, and earlier reptiles.
Marine Lizards Today's turtles belong to this lineage.
Reptiles CROCODILIANS
Scutosaurus SAUROPTERYGIANS TAIL Cranial
Hylonomus was short in Opening
Snakes, Lizards, and
Sphenodonts relation to the
animal's body size.
CAPTORHINIDS ARCHOSAURUS
AND HYLONOMUS Antorbital fenestra
TEETH
Small and irregular,
Archelon
Diapsid they allowed the ORDERS OF
skull animal to cut buds REPTILES
for food. 5 EXIST TODAY. DIAPSID
FEET
ANAPSIDS Canine teeth in the were appropriate During the Permian Period, another
upper mandible group of reptiles emerged that had
SHELL for the animal's
was a structure formed by bony body weight. It temporal openings in the skull behind
REPTILES ribs that developed from the moved slowly. FLIPPERS each eye socket.
maintained the body's
vertebrae of the spine. balance while it moved.
Great Turtle
The Archelon ischyros was a giant marine
reptile that measured 15 feet (4.6 m) in
length. It inhabited North America during TAIL
the Upper Cretaceous (between 75 and 65 was very flexible,
million years ago). An omnivorous feeder,
it passed slowly through shallow and it provided great
waters by means of the propulsion agility for swimming.
provided by its flippers. The
females laid eggs in holes just
like the sea turtles of today.
Weight
4,900 pounds
(2,200 kg) MILLION YEARS
and slippery. 160 IS THE AGE OF THE
SKIN
was smooth
MOST PRIMITIVE SEA
Weight 660 pounds (300 kg)
CROCODILE FOSSIL.
10 feet (3 m)
15 feet (4.6 m) METRYORHYNCHUS
GIANT FLIPPERS ARCHELON Sea Crocodiles
were used to move Scientific Name Metriorhynchus sp.
through the water. Scientific Name Archelon ischyros This genus of reptiles owes its name to its Diet Squid and Pterosaurs
members' long snouts. The sea crocodile was a
Diet Omnivorous
MOUTH dangerous hunter, capable and opportunistic. It Habitat Marine
had a beak like a pounds Habitat Marine JAW preyed on squid and pterosaurs, and it chased fish
hook. It did not was thin and up to 20 feet (6 m) long—twice its own size. Its Location South America
(Chile) and Europe
tail got thinner toward its end, which had a flipper.
cut, but its bite 4,900 (2,200 kg) Location North America pronounced, with There was a small bump between its eyes. Sea (France and England)
was deadly. Era Upper Cretaceous small and sharp crocodiles lived near the end of the Jurassic Period.
IS WHAT THESE SEA TURTLES COULD HAVE WEIGHED. Era Jurassic
teeth.