- GENEVA(Reuters) - Dinosaur tracks discovered on a cliffside in Bolivia
show that many species of the creatures that ruled the earth for millions
of years lived side by side, according to a Swiss paleontologist. Christian
Meyer of the University of Basle, just back from the site of Cal Orcko
near the city of Sucre, told the newspaper Le Matin that it was a ``dinosaur
El Dorado'' and probably the world's most important site for their study.
Meyer said the some 3,000 footprints making up 250 different tracks over
the cliff face of 25,000 square metres dated from 68 million years ago,
or three million years before dinosaurs were wiped out, apparently when
a vast meteor hit the planet. ``The most extraordinary thing is the diversity
of the species represented and the fact that they all date back to the
same period,'' he told the newspaper. Tracks identified included those
of a meat-eating therapod that could grow up to seven metres long, a lumbering
titanosaurus which measured 15 to 25 metres, a smaller, armoured ankylosaurus,
and vegetarian ornithopods which walked on two feet. ``The whole carnival,
the whole range is there,'' said Meyer. ``This is the first site which
makes it possible to show that these species lived at the same time and
in the same place until just before their extinction.'' Many other dinosaur
tracks have been found around the world, especially in the mid-West of
the United States in the Rocky Mountains and some in Switzerland high in
the Alps near the border with France and Italy east of Mont Blanc. But
at the Bolivian site, Meyer said, the number and variety of prints was
the greatest yet discovered. One theropod track was 350 metres long. Some
prints left by the larger dinosaurs -- first identified as a common group
in 1841 by early British paleontologist Richard Owen -- were 60 cm across.
The area of the Bolivian site was once covered by a vast freshwater lake.
The dinosaur tracks were made along its shores in heavy mud which then
solidified and filled with loose shale, as in similar sites elsewhere.
Later volcanic activity raised the bank, turning it into a towering cliff
whose local name means ``Chalk Mountain.'' Meyer said the tracks were first
found in the early 1980s by workers at a local cement quarry, but it was
not until 1994 that a Bolivian geologist identified them as dinosaur footprints.
The 42-year-old scientist, with a grant from Switzerland's National Fund
for Scientific Research and backing from private sponsors, led a 15-member
international team to carry out a full survey of Cal Orcko over six weeks
in July and August. He said they had made silicone copies of the most interesting
prints, using mountaineering techniques to scale the sheer cliff face.
Another discovery in the area was the fossil of a flying reptile 40 cm
long. Most paleontologists now believe that smaller dinosaur survivors
of the meteor holocaust 65 million years ago evolved into birds.
|
