14 Sharks: The Animal Answer Guide(“spiral saw”) had a lower jaw and tooth form unlike any living shark, its
teeth arranged in a spiral of replacement teeth rather than a toothy grin.
Until a more complete fossil of the head of a relative was found, research-
ers did not know what Helicoprion was (some thought it was a relative of the
chambered nautilus, a mollusk) and where on the body the tooth spiral was
located.What are the largest and smallest sharks alive today?
Before an answer to the question of large sharks can be given, we have
to admit that very large sharks are hard to catch and notoriously difficult
to measure accurately. Many accounts estimate (or guesstimate) size, with
characterizations such as “bigger than the boat,” or try to deduce length
from photographs. Weights are even less often accurately measured be-
cause scales capable of dealing with animals that weigh many tons aren’t
always available when a super-large shark is hauled to a dock or boat ramp.
As a result, verified maximum lengths are often shorter than suspected
maximum lengths, and exaggeration is not unknown.
Recognizing these limitations on accuracy, we know which species are
largest, but we don’t really know how big they get. The largest shark—and
for that matter, the largest fish alive today—is the Whale Shark, RhincodonHelicoprion bessonovi, an edestoid shark that lived in the late Paleozoic and early Mesozoic eras ( 300 to 200 million
years ago). It is thought to have grown to 3 to 4. 5 m ( 10 to 15 ft) in length. Its “circular saw” jaw and tooth arrange-
ment are unlike those of any living shark, and its body shape remained a mystery for many years. (A) Fossilized re-
mains of the lower jaw, about 26 cm ( 10 in) in diameter; (B) hypothetical reconstruction of the animal. A, from J. Walther
( 1914 ), Wikimedia Commons, http://en.wikipedia.org/wiki/File:Helicoprion_Bessonovi 2 .jpg; B, drawing by Dmitry Bogdanov, Wikimedia Commons,
http://en.wikipedia.org/wiki/File:Helicoprion_bessonovi 1 DB.jpg
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