Scientists report evidence of billion year old worms

September 30, 1998
Webposted at 1:45 PM EDT

NEW HAVEN, Conn.(CNN) -- Yale University researchers say they have found fossil evidence that worm-like animals lived on earth more than a billion years ago. Previously, the earliest fossil evidence of multicellular animals was thought to be about 580 million years old.

The new finding suggests complex animal life evolved on earth much earlier than previously thought.

The research was conducted by Adolf Seilacher of Yale University, and colleagues.

The results are published in this week's edition of the journal Science. Significantly, the Yale team did not find fossils of the worms themselves, but rather "trace fossils" - tunnels in rock that may be burrows that were formed when the worms wriggled through sand. The burrow structures were preserved when the sand solidified into rock 1.1 billion years ago.

The sandstone rocks were discovered in what is now central India.

"Trace fossils" are somewhat controversial, because scientists cannot completely rule out the possibility that the burrow structures were formed in the rock by some geological or other physical process. In that case, the "tunnels" would have nothing at all to do with animals of any kind.

Seilacher says, however, that his team gave careful consideration to that possibility and they believe the fossils can be best explained as the trails of worm-like animals.

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