Photo by David
Dr. Randy Miller and Dr. Sue Turner are excited
by the clues a shark
fossil found near Campbellton is revealing about
DISCOVERY SET IN STONE
Shark fossil giving teeth to new
By NINA CHIARELLI
fossil that has been sitting in the basement of the New Brunswick Museum since
it was found near Campbellton in 1997 could change science's understanding of
the evolution of vertebrates.
That's because it is the
oldest shark specimen known to have teeth inside its jaw.
Dr. Sue Turner, a vertebrate paleontologist with the
Queensland Museum in Australia and an expert in shark fossils and early fish,
arrived this week to study a complete shark fossil discovered more than five
years ago near Atholville. It, is the oldest in the world and dates back 430
million years to the Devonian Age.
"It was a time when
our ancestors, the fishes, really got going," she said.
A fossilized shark
tooth is seen inset here.
Dr. Turner is
studying at the museum for two weeks on a research grant. She said the
discovery of an intact shark skeleton, a Doliodus problematicus less than
one-metre long, indicates both the environment and the rock that housed the
fossil were quite special.
"We think this rock is
probably mud from a lagoon.
It's very, very fine grained,
and, probably it was quite a warm lagoon on the edge of the sea," she
Past findings have included single teeth and scales
because sharks are. mostly made of cartilage, something that doesn't preserve
well, Dr. Turner said.
"Sharks are quite rare in the
fossil records," she said.
"Certainly complete ones are
very very rare."
Since shark physiology has'nt changed
much over time, Dr. Turner said the fossil opens new doors for research and
speculation because it proves shark fins once had spines.
"It's quite unusual," she said. Up to now her field was
unaware that any sharks had spines in their pectoral fins.
"Certainly it could probably change the ideas of how we
think of vertebrate evolution," she said.
already it's telling us that one idea we had about sharks, that they didn't
have fin spines on their paired fins, is wrong.
ancient fish were thought to lack jaws, and instead had cartilage supporting
their bronchials regions, with scales all over their mouths, Dr. Turner said
the specimen could help scientists understand why humans still have teeth.
"We're really at the moment trying to understand how
"Originally there were lots and lots, of
teeth in the jaw of a fish, and now we (as humans) are restricted to very few.
"And we have a very short jaw that is getting shorter."
It also proves teeth really haven't changed much in about
400 million years since they evolved from scales.
this ... we don't even have any teeth shown in
Dr. Randall Miller, curator of geology and
paleontology of the New Brunswick Museum, said having Dr. Turner on hand to
explain the significance of the fossil has been extremely important.
"It's great to have someone like Turner here because we
have fossils of a wide range in New Brunswick and my expertise is in one group
of fossils and there's no way that at the museum we can study in detail the
wide variety that we see," he said.
Dr. Miller studies
Ice Age beetles, which only date back about 100,000 years.