Page 36 - Dinosaur (DK Eyewitness Books)

Plant-eaters

TȩȦ ȫȢȸȴ ȵȦȦȵȩ ȴȵȰȮȢȤȩ Ȣȯȥ Ȩȶȵ of herbivorous (plant-eating)
dinosaurs were made for cropping, chewing, and digesting
vegetation. Broad-snouted armored dinosaurs were unfussy eaters,
Square
jaw while armored dinosaurs with a narrow snout picked out just the
plants they liked. Sauropods stripped twigs with teeth shaped like
spoons or pencils, then swallowed leafy mouthfuls whole. The beaks
of horned dinosaurs sliced through tough, fibrous vegetation that
their sharp cheek teeth chewed into pulp. Hadrosaurs (duck-billed
dinosaurs) cropped leaves with their toothless beaks and chewed
them with batteries of cheek teeth. Most ornithischians probably
had fleshy cheeks to hold food while chewing. All of these herbivores
had long intestines to digest large amounts of plant food.

Small intestine
Numerous teeth
MOWING MACHINE SAUROPOD DIGESTIVE SYSTEM
Nigersaurus had more teeth than any other Leaves swallowed by a sauropod passed
sauropod, and these lined the front of its through its long intestine, where they
shovel-shaped mouth. Its lower jaw alone bore were digested into simple substances
68 teeth, and behind each pencil-shaped front that could be absorbed into the
tooth grew many more to replace the teeth blood and carried around the body.
as they wore out one by one. Nigersaurus was Leaves are not very nourishing, so
short-necked and could not graze on foliage sauropods had to eat lots to fuel
high up in the trees. Like a living lawnmower, their large bodies. The ancestors
it cropped low-growing ferns and horsetails. of sauropods walked on their hind
limbs, but the weight of the guts
held in front of the hip bones caused
them to evolve (become adapted)
over time to walking on all fours.
STONES IN THE GUT
Smooth stones found in the remains of some
sauropods led paleontologists to believe that the Large
dinosaurs swallowed them for use as millstones. Gizzard intestine
Sauropods may have had a gizzard (muscular organ
for grinding food) like a bird’s. Gastroliths (“stomach
stones”) were thought to have ground up plant matter
in the gizzard. But German scientists found that
stones in the gizzards of ostriches were rough.
They concluded that the sauropods swallowed
stones either by accident, or deliberately for
the nourishing minerals in the stones.

Sharp edge of new
tooth helped in
shredding leaves

Tooth worn down by
eating plants

WEAR AND TEAR
Two saw-edged Iguanodon cheek teeth—one
new, the other worn—show the effects
of chewing tough plants such as horsetails
rich in the abrasive substance silica. Each
time Iguanodon bit off a leafy mouthful and
closed its mouth, the two side rows of upper
teeth slid across the surface of the lower
teeth, grinding the leaves. This kept the
Iguanodon teeth teeth sharp, but also wore them down.

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