SCIENTIFIC AMERICAN : Fossil Find
Hints at Aquatic Origin for Flowering Plants
by
Sarah Graham on May 3, 2002
Scientists have discovered in China
the oldest, most complete flowering plant fossil yet, according to a new
report. The 125-million-year-old specimen belongs to a new plant family and
provides clues as to how now extinct species gave rise to modern flowering
plants, or angiosperms. The work, published today in the journal Science,
suggests that angiosperms--the dominant vegetation in the world today--may have
evolved from aquatic, weedy herbs.
Ge Sun of Jilin University in China
and his colleagues recovered the complete fossil of the plant, dubbed Archaefructus sinensis, from a slab of
rock found in northeastern China's Liaoning Province by local farmers . The
region, which has produced an array of remarkable fossils, yielded a similar
but incomplete fossil in 1998. "After having only a fragment and trying to
imagine what the whole plant was like, it was a great surprise to find leaves
typical of a plant that lived underwater with characteristics very unique to
flowering plants at such an early age in their history," says study
co-author David L. Dilcher of the University of Florida. Although the plants
lacked flowers, the scientists discovered evidence of seeds enclosed within the
female reproductive organs, a characteristic of flowering plants. With its
thin, curving stems, A. sinensis had
a vaguely seaweed-like appearance.
To determine how their find fits into
the evolutionary family tree, the researchers compared the traits evident in
the fossil plant with genetic and morphological information from 173 modern
flowering plants. The results indicate that the specimen represents a
previously unknown family, Archaefructaceae, with two species A. liaoningensis and A. sinensis. The authors propose that
Archaefructaceae is a sister group to all exant angiosperms. Further research
is needed before Archaefructus is
fully accepted as the most ancient flowering plant known, but botanists are
excited about its implications. "The mysteries of the origin and radiation
of the flowering plants remain among the greatest dilemmas facing paleontology
and evolutionary biology," says plant biologist William L. Crepet of
Cornell University. He adds that the new fossil is "one of, if not the
most, important fossil flowering plant ever reported."
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