Lower
jaw
Rounded teeth
Upper
jaw
Section view (front)
Upper,
ded teeth Adult
Four rotations
New tooth
formed
here
Great white
Helicoprion
Juvenile
Two rotations
Newest
tooth
First
three
teeth
New tooth
One
rotation
40 ft, maximum length
Helicoprion Narrower body
Great white
20 ft
Gum
line
Root
Root
Enamel
Modern sharks shed old teeth to make
way for new ones. Helicoprion juveniles
were born with three teeth they never lost;
new teeth shifted old ones in rotations
of up to 150 teeth encased in cartilage
and attached to a single root.
WHIRLING INTO ADULTHOOD
he jaw snapped shut, it forced
ged spiral into a notch in the upper
d with small, rounded teeth. Prey
ckly sliced in two and swallowed.
Actual size
of teeth from a
large whorl fossil
1.5 feet in diameter
Fossil
Reconstruction
ice
EQUATOR
osphoria Sea
LaurussianSeaway
Paleotethys
Neotethys
PANTHA
LAS
SA
NTH
ALASS
A
PA
NG
AE
A
daho, U.S. Kazakhstan
Ural MRussiats.,
Australia
Mexico
Canada
Japan
islandsArctic
Laos China
EQUATOR
OCEANATL.
OCEANPACIFIC
OCEANPACIFIC
INDIANOCEAN
AFRICA ASIA
AUS.
EUR.
SOUTHAMER.
N. AMER.
Idaho, U.S. Ural MRussiats.,
Modern fossil sites 282–275 million years ago Number of fossils found since 1886: 1 2-5 25 100
RAPHIC MAP) PHOTO: EVELYN VOLLMER AT IDAHO VIRTUALIZATION LAB, IDAHO MUSEUM OF NATURAL HISTORY
DECODER FERNANDO G. BAPTISTA AND PATRICIA HEALY