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scratches on their teeth. Unnoticed by either the hadrosaurs or the tyrannosaur, the
herd was attracting the attention of thousands of dung beetles. These insects bur-
rowed industriously into the feces and laid their eggs, the dung providing both a
home and high-quality food for their progeny. Snails also grazed on the droppings,
gaining plenty of nutrition from the digested plant material.
The
Tyrannosaurus
turned her massive head slowly to the left to get a better
fix on a potentially easy target. There: a half-grown
Edmontosaurus
had become
curious about the sounds of ceratopsian conflict and separated himself from the rest
ofthe herd. She locked her vision onto him and shifted her weight to that side. Mud
oozedbetweenhertoesandaprominentridgeformedontheoutsideofherleftfoot.
Starting with her feet together, she began stalking, taking a series of steps punctu-
ated by pauses. Right, left, stop; right, stop; left, stop; right, left, stop. The breeze
flowed down the river valley in the opposite direction of her movement, masking
her sounds and scent. Within minutes, she was close enough to pounce, and did.
Hertinyarmswereuselessforgrabbingthe
Edmontosaurus
,soshelungedfor-
ward with her best asset: a mouth full of stout, banana-sized serrated teeth, backed
up by the most powerful bite of any land animal that had ever evolved. Unfortu-
nately for her, but fortunately for the hadrosaur, a crunching branch on her next-to-
laststeprevealedherclosepresenceinanotherwisestealthyapproach.The
Edmon-
tosaurus
lurched to his left just when the tyrannosaur's jaws clamped down on the
uppermost part ofhis tail. This action removed achunkofthe hadrosaur butleft the
rest of the animal running away on his back two legs, hooting loudly in pain and
fright. The other hadrosaurs in the herd likewise switched to faster bipedal postures
and quickly moved away, making much noise and stomping on mud, plants, dung,
dung beetles, and snails with their stout feet.
Thetyrannosaurtrailedtheretreatinghadrosaursforafewminutes,justincase
the one she had bitten would falter from his wound, or some other straggler in the
herd would make itself available to her. Her tracks first paralleled and then turned
in harmony with the herd's trackways as she followed them. As the distance separ-
