18 Sharks: The Animal Answer Guide
to catch the fastest tuna, anymore than the cheetah has to catch the fastest
gazelle. Slower ones are just as tasty.
What is the largest shark that ever lived?
If we disregard the speculated lengths of the living Whale Shark, the
largest true shark in terms of weight to swim the seas (or lakes) occurred
around much of the world during the mid-Miocene through the Late Plio-
cene, 16 to 1.6 million years ago. This creature was Carcharocles megalo-
don, the Megatooth Shark. Recent fossil evidence has confirmed the need
to change the Megatooth’s genus name from Carcharodon to Carcharocles
because we now know that modern White Sharks—Carcharodon—evolved
from mako shark ancestors, not Megatooth ancestors. Researchers pre-
viously thought a direct connection existed between the Megatooth and
White Sharks because of tooth similarities, but new fossil findings confirm
separate ancestries and therefore identities (although not all experts agree
on this change).
Giant teeth from the Megatooth Shark are found in fossil deposits on
land and in the sea in Europe, Africa, Australia, India, Japan, North and
South America, and some western Pacific islands. The largest teeth ever
found came from South Carolina and Peru and measured 17.6 to 17.9 cm
(7.25–7.37 in) from the tip to the end of the root, or base, with an enamel
height of 16.8 cm (6.9 in). Paleontologists use a formula for calculating
shark length based on tooth size, but they use enamel height rather than
total tooth size because teeth vary greatly in root shape. They also make
the reasonable assumption that the proportions of the Megatooth Shark are
similar to those of the White Shark. A Megatooth Shark with an enamel
height of 168 mm would be about 16 m (52 ft) long and weigh approxi-
mately 48,000 kg (105,000 lb). The jaws of such a monstrous shark would
have been more than 1 m (3.25 ft) wide, the dorsal fin would be 1.4 m (4
ft) high, and the tail would be 1.75 m (6 ft) tall. Several people have recon-
structed the jaws using entire sets of fossilized Megatooth teeth.
The Megatooth Shark, although probably the largest predatory shark
that ever lived, occurred with other relatively gigantic 5- to 6-m long (16–
20 ft) predators during the same time, including the Speartooth Mako (Isu-
rus hastalis) and a hemigaleid, Hemipristis serra, a relative of the modern
Snaggletooth Shark, Hemipristis elongatus. Megatooth Sharks also swam the
seas with their smaller cousin, the White Shark.
http://www.ebook3000.com