New Fossil Is World's Oldest Plant-Eating Lizard

March 24, 2008

A rare fossil discovered in Japan is the oldest known plant-eating lizard, which could shed light on an evolutionary puzzle that Charles Darwin described as an "abominable mystery," scientists say.

The 130-million-year-old jaw and skull bones were unearthed in the Ishikawa Prefecture of Japan (see map of Japan).

Based on the size of the skull, the researchers estimate that the lizard measured between 10 to 12 inches (25 to 30 centimeters ) in length.

Prior to the new discovery, the oldest known plant-eating lizard was Dicothodon, which lived in North America about 100 million years ago.

Even today, fully herbivorous, or plant-eating, lizards are rare, with only about 3 percent of modern lizards belonging to the group. Most lizards eat flesh, usually insects, or a combination of flesh and plants.

Modern herbivorous lizards eat flowering plants, or angiosperms, whose buds and leaves are typically softer than nonflowering plants.

Thus the new fossil species, dubbed Kuwajimalla kagaensis, could indicate that angiosperms were already in existence and perhaps widespread millions of years earlier than had been thought, the researchers say.

"By finding this particular fossil from Japan, it might suggest that flowering plants were already there, but we don't have direct evidence yet," said study team member Makoto Manabe of Japan's National Science Museum in Tokyo.

The discovery is detailed in a recent issue of the journal Paleontology.

Darwin's Dilemma

Currently the oldest evidence a flowering plant is a 125-million-year-old fossil from China.

The apparently sudden appearance of angiosperms in the fossil record confounded Darwin, who worried that it might pose a problem for his theory of evolution by natural selection.

Continued on Next Page >>




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