By Patricia Reaney
LONDON (Reuters)
- A volcanic eruption in northern China 150 million years ago
has provided scientists with a treasure trove of fossils showing
that salamanders originated in Asia, scientists said Wednesday.
Hot ash from
the volcano spewed into a small lake near Fengshan in Hebei Province
about 250 miles north of Beijing and petrified more than 500 salamanders
in the amphibian equivalent to Pompeii.
The remains
are 85 million years older than previous specimens and fill a
huge gap in fossil records -- an important tool for understanding
the evolution of the mythical lizard-like creatures.
"The
simple, take-home message is that there is an Asian origin for
all salamanders," said Neil Shubin of the University of Chicago.
From what
they have uncovered Shubin and Ke-Qin Gao, of the American Museum
of Natural History in New York, believe that salamanders evolved
earlier than previously thought and that the creatures have changed
little since they roamed the Earth alongside dinosaurs.
"For
the first time we have a large supply of salamander samples to
understand their evolution," Gao said in a telephone interview.
The fossils,
described in the latest edition of the science journal Nature,
show all the stages of the lives of the amazing creatures that
survived the event that wiped out the dinosaurs. Ironically, and
to the puzzlement of scientists, they are disappearing today.
Salamanders
are one of three types of amphibians but Gao said they are the
least understood. They are a type of living fossil because they
have such a primitive body type yet have the poorest fossil record.
"Now
we not only have the earliest fossil record but also a very large
sample and several kinds of salamander all in one site,"
Gao explained.
One of the
most intriguing features about salamanders is how little they
have changed and how different types of the creatures evolved
the same features independently in a process called parallel evolution.
The fossils
may shed some light on parallel evolution and could help researchers
understand another perplexing feature about the creatures -- how
the adult animal can retain juvenile characteristics.
"Whether
you look at a salamander you find under a rock in the local forest
preserve or in a rock in China dating back 150 million years,
they look alike. In fact, they look alike in great detail -- the
bones in their wrists are the same, the way their skulls are formed
-- intricate details are the same," Shubin added in a statement.
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