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Article from yesterday's Mercury News



Ocean floor sediment yields clues on dinosaurs

         
            BOSTON (Reuter) - Layers of sediment collected from the
ocean floor off the coast of Florida suggest that a massive
meteorite struck the earth 65 million years ago and led to the
extinction of dinosaurs, scientists said Wednesday.
            Sediment cores collected by an international team of
scientists aboard the JOIDES Resolution drilling ship indicate
that 70 to 80 percent of the Earth's species were killed in the
collision, they said.
            The cores contain ``a really beautifully preserved record of
what the oceans were like in the distant past,'' Dr. Richard
Norris, a paleontologist from the Woods Hold Oceanographic
Institute in Massachusetts told Reuters from the vessel.
            ``We can go back and look in the distant past and look at
the oceans and the climate and the kinds of organisms that were
alive at that time, what they were really like,'' he said.
            JOIDES, the Joint Oceanographic Institutions for Deep Earth
Sampling, is funded by 20 countries and is managed by Joint
Oceanographic Institutions Inc, a non-profit group of 10 major
U.S. oceanographic institutes.
            Scientists theorize that the impact of the six-mile
-wide meteor caused dust and gases and other materials to be
spewed into the atmosphere, blocking out the sun and killing off
micro-organisms, setting off a chain reaction. The blast is
dated at about the same time the dinosaurs died out.
            Drilling 10,000 feet under water, about 240 miles east of
Florida, the scientists found green clay pellets which they said
were fragments of glass thrown into the atmosphere when the
meteorite hit.
            Sharply differentiated layers of mud and clay, which could
mark the periods before and after the collision, contained
different kinds of microscopic plants and animals -- including
some which are the predecessors of today's micro-organisms,
Norris said.
            Shallower sediment from 35 to 45 million years ago, when the
world was much warmer, may provide clues of what would happen if
the Greenhouse Effect takes place, he said.
            ``We would like to know what the world would be like if we
keep on pumping carbon dioxide into the atmosphere and create
our own little greenhouse,'' he said.
         ^REUTER@