Polish Scientists’ Discovery Will Force Rewrite of Books

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http://www.polamjournal.com/News/Feature/feature.html

Polish Scientists’ Discovery Will Force Rewrite of Books

by Leo Kretzner

WARSAW, Poland — Polish scientists led by Dr. Grzegorz Niedzwiedzki of Warsaw University have made a major fossil discovery near Zachelmie, Poland. It is something even rarer than fossil bones — fossilized footprints.

These tracks are preserved in mud that became stone, which Dr. Niedzwiedzki and colleagues have shown to be 397 million years old. Their discovery’s significance lies in the fact that this is 18 million years earlier than the first animals with limbs and feet – the first land animals - were thought to have existed.

The earliest known fossils of four-limbed animals are about 380 million years old, with no evidence they existed before that.

“Dr. Niedzwiedzki and colleagues lob a grenade” into the accepted timing of animal evolution, according to Dr. Philippe Janvier and Dr. Gael Clement of the French Museum of Natural History, in a commentary announcing the discovery in the journal Nature. A photo of the tracks appears on the cover of Nature, which many consider to be the topmost weekly scientific magazine in the world.

The dozen sets of tracks were discovered in a quarry in the Holy Cross Mountains (Gory Swietokrzyskie). They were left by animals between 20 inches and 8 feet long, based on analysis of their size and spacing. Many of the prints show clear signs of early claws or digits of some kind. The biologists showed the patterns and spacing of the tracks was consistent with how four-legged animals move.

“The match between these tracks and the limb anatomy of Ichthyostega [the oldest limbed fossil] is impressively close,” say Drs. Janvier and Clement in their comments.

Dr. Niedzwiedzki was joined in his work by colleagues Piotr Szrek, also of Warsaw University, Katarzyna Narkiewicz, and Marek Narkiewicz, of the Polish Geological Institute, Warsaw, and Per Ahlberg of the University of Uppsala, Sweden.

The Polish scientists’ discovery indicates that older fossils of the earliest land animals remain to be found. They must have been there — after all, they clearly ‘walked the walk’.

Leo Kretzner is a biologist and science writer in Claremont, Ca.