Page 37 - Dinosaur (DK Eyewitness Books)

Long neck helped in
reaching leaves on treetops

TREETOP BROWSER
Built like a gigantic giraffe, Leaves of
Brachiosaurus raised its head to monkey puzzle tree
browse among the leafy twigs
of conifers such as monkey New teeth Battery of closely
puzzle trees. This sauropod’s growing packed teeth Tall, unbranched trunk
name means “arm lizard,”
which is a reference to its
long forelimbs. Its big,
spoon-shaped teeth were
better at biting off tough
leaves than Diplodocus’s
pencil-shaped teeth,
which served as rakes GREAT GRINDER
for stripping vegetation. Hadrosaurs such as Edmontosaurus had many small cheek
teeth arranged in upper and lower tooth batteries, each of
which held up to 60 groups of three to five teeth. When
Edmontosaurus chewed a mouthful of pine needles or
other leaves, the upper teeth slid sideways over the lower
ones, crushing the leaves while sharpening the teeth.
Brachiosaurus

PARROT BEAK
The name Psittacosaurus (“parrot lizard”)
was inspired by this ceratopsian’s parrotlike
cutting beak. Parrots can slice through
tough-skinned fruits and crack open
nuts. Psittacosaurus could do the same
by closing its sharp beak on the bone
at the tip of its lower jaw—a feature
common to ornithischians—before
chewing food with its cheek teeth.
Predentary (bone at the
tip of the lower jaw)
Cheek tooth

Dentary (lower jaw bone)
Tusk
Sharp front tooth
THREE KINDS OF TEETH
Heterodontosaurus (“different tooth lizard”)
was a small, early ornithischian with three
kinds of teeth. Front teeth bit against a
horny beak to snip off mouthfuls of tough
vegetation, which was then crammed into
cheek pouches. Cheek teeth mashed this food
to pulp. Tusks fit into grooves in the jaws and
were perhaps used by rival males in threat displays.

Small head Toothless
beak
Chisel-shaped cheek tooth
A MIXED DIET
Most ornithischians had a beak instead of
front teeth, but dog-sized Lesothosaurus, an
early ornithischian, had upper front teeth that
were less specialized for chewing plants than
those in later kinds. This perhaps indicates that
ornithischians evolved from dinosaurs that were
not plant-eaters. The ridged teeth that rimmed
Lesothosaurus’s jaws helped it chew low-growing
plants and could have also tackled other kinds of
food such as insects, lizards, eggs, and dead animals.

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