評論
打印
Scientists Find World's Oldest-known Animal
A millipede-like creature that was recently discovered in Scotland may be the oldest-known land animal. This small, fossilized creature, some 425 million years old, helped lead the way for the many animals that would eventually live on land.
Researchers said they found the creature's remains on the island of Kerrera in Scotland's Inner Hebrides. It lived close to a lake and probably ate dead plants. Fossils of the oldest-known plant with a stem were found in the same area.
While the creature, called Kampecaris obanesis, is the earliest land animal known from a fossil, soil worms are believed to have lived before them — perhaps 450 million years ago.
That information comes from Michael Brookfield of the University of Texas at Austin and the University of Massachusetts Boston. Brookfield was the lead writer of the research report that described the findings in the journal Historical Biology.
Kampecaris was about 2.5 centimeters long. It looked like modern millipedes, but it was a member of a group that died out. It was not a direct ancestor of the millipedes that live now.
Life first began in the world's oceans, with a growth in diversity some 540 million years ago. Some kinds of plants began appearing on land around 450 million years ago. The land vertebrates — animals that have a backbone or spine — showed up some 375 million years ago.
These animals were the ancestors of the reptiles, birds and mammals that are alive today — including humans.
Human beings first appeared about 300,000 years ago.
I'm John Russell.
