Page 29 - Dinosaur (DK Eyewitness Books)

Tiny cerebrum COMPARING BRAINS
Antorbital Tyrannosaurus’s skull was immensely
fenestra (window bigger than a human skull, but much of it
in front of opening was taken up by toothy jaws. Compared
for eye) Brain cast with ours, its brain was relatively small,
although far larger than those of many
dinosaurs. Scientists made a cast of the
hollow inside the dinosaur’s skull once
occupied by the brain. They found small
bumps on the cast that were interpreted
as Tyrannosaurus’s tiny cerebrum—the
part that makes up most of the human
brain. Our large cerebrum makes speech
and thinking possible. With a simpler
lifestyle than our own, Tyrannosaurus
managed very well with a brain that mainly
supervised the muscles and the senses.

Cerebrum forms
Tyrannosaurus 85 percent of the
skull human brain

Cerebellum
controls
Human skull movement
and the senses

48,&.ʜ:,77('"
Troodon had a heavier
brain in relation to
its body weight than HUNTING IN PACKS
almost any other In this old illustration, a Deinonychus pack works together to bring down
dinosaur. Scientists believe a big ornithopod called Tenontosaurus. Clues for such encounters come
that its brain may have been as from fossils of these dinosaurs found near each other in some quarries.
sophisticated as that of a cassowary, a modern Some paleontologists think that certain theropods’ sophisticated brains
flightless bird similar to Troodon in size. This enabled them to hunt together like wolves. Others believe that perhaps
theropod probably could track and ambush prey the theropods died separately but the corpses ended up together when
and was well adapted to its role as a hunter. a river dumped them on a sandbank.

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