Page 60 - Dinosaur (DK Eyewitness Books)

Eggs and young

DȪȯȰȴȢȶȳȴ ȩȢȵȤȩȦȥ ȧȳȰȮ ȩȢȳȥ ȴȩȦȭȭȦȥ eggs like those of
birds and crocodiles. By studying a fossil eggshell’s shape and texture,
paleontologists can tell which type of dinosaur laid the egg. Sometimes
they even find a tiny skeleton inside the fossil egg. Such discoveries
include the remains of whole nesting colonies of hadrosaurs and
sauropods. Small dinosaurs probably sat on their eggs to warm them as

A GIANT’S EGGS birds do, but big dinosaurs hatched their eggs with warmth from sunshine
Sauropods’ cannonball-shaped eggs or rotting vegetation. Some dinosaurs ran around and started looking for
measured about 5 in (13 cm) across.
Each occupied the space of a dozen food soon after emerging from eggs. Others needed parental care. Most
chicken eggs. A thick shell protected kinds of dinosaur grew fast. A Tyrannosaurus that hatched from an egg no
the egg from breakage and tiny holes
in the shell let air reach the embryo bigger than a loaf of bread weighed as much as 65 lb
inside. These eggs seem small for
the size of the huge plant-eating (30 kg) by the time it was two. By 14, this theropod
dinosaurs that laid them, but much weighed about 1.9 tons (1.7 metric tons), and
larger eggs would have needed
shells so thick that hatchlings more than twice that by 18. But it did not live
could not have broken out. long: by 30, the Tyrannosaurus was dead.

Head tucked in
Damage caused
during fossilization
READY TO HATCH
Tiny bones found in a fossil egg helped a
modelmaker to create this lifelike restoration
of a Troodon about to hatch. Such eggs have
been found at Egg Mountain, a Late Cretaceous
fossil site in the northwest of Montana. Troodon
mothers laid eggs two at a time. Incubated
upright in the ground, their clutches hatched
out into babies that quickly ran around. Fossils
of young and adult dinosaurs found together
make it likely that the hatchlings
formed part of family groups.

Tail tucked
under body

Elongated
shape

STOLEN GOODS?
Oviraptor and its relatives—
the oviraptorids—laid
narrow, hard-shelled eggs
like this one, discovered in
Mongolia. These eggs are
typically 7 in (18 cm) long. DINO KIDS
Oviraptor means “egg thief.” This realistic model shows Maiasaura hatchlings crouching in
Scientists once thought that a small the protection of their mud-mound nest among unhatched
ceratopsian called Protoceratops laid eggs. Maiasaura was a large hadrosaur (duck-billed dinosaur)
the eggs and that Oviraptor used to steal and dozens of individuals nested close together. Like birds,
them. The scientists realized their mistake the mothers fed their babies in the nests until they were
only when paleontologists found fossils strong enough to leave. This habit earned this dinosaur
of another oviraptorid sitting on similar eggs. its name, which means “good mother lizard.”

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