Burgess Shale--Evolution's Big Bang
February 2 - April 28, 2002
An ancient underwater earthquake
preserved startling proof of early life forms
Earth formed 4.6 billion years ago, and about a billion
years later the most primitive life-form--single celled bacteria--became
dominant, and remained so for the next three billion years.
Then a burst of evolutionary creativity, beginning about
600 million years ago, produced complex multicellular animals that appear
in the fossil record. Much of what
science knows about the "Cambrian Explosion" of life comes from
the fossil record in the Canadian Rockies, and especially a site known for
its "Burgess Shale," discovered in 1909 by Charles Walcott, then
secretary of the Smithsonian Institution.
The shallow waters of the ancient sea once teamed with
unusual organisms, as all types of life-forms diversified in the quest for
survival. During the Cambrian period
the blueprint for virtually all the major groups of animals was laid down
in a blink of geologic time. Among
these organisms was the two-inch, slightly flattened worm, Pikaia, the
first primitive chordate in the sea, ancestor to all vertebrates, such as reptiles,
dinosaurs, birds, and mammals. One
giant for its time, the 40-inch Anomalocaris,
roamed the seas preying with large claws on smaller creatures.
Then at one point along the edges of the Continental
Shelf a great underwater mud slide, probably triggered by an underwater
earthquake, suddenly buried every living organism within reach in a mass of
fine clay silt that filled even their insides, preserving their
three-dimensional shapes. The
organisms were permanently buried in the dark, in water up to 100 feet
deep, with no bacterial life to decay or destroy their bodies. The preserved bodies of this rich, watery
biozone were locked forever in a clay-like mud, anatomically true to life, and
faithful in every delicate detail of their soft body parts.
Millions of years after the seas had been dried up, the fossil-rich sedimentary rock was raised up by
gigantic forces of the Earth. In
1909,
paleontologist Charles Walcott stumbled on this mother-lode
of exquisitely detailed fossils.
Near the Burgess Pass Trail in the Canadian Rockies, he saw an
amazing snapshot of the diversity of life from more than 500 million years
ago, and glimpsed the "Big Bang" of evolution. Walcott collected
tirelessly, and through the years brought back to the Smithsonian more than
65,000 fossils, one of the Institution's greatest treasures.
The evidence of Cambrian life forms in Burgess Shale
called for many scientists to rethink the Darwinian theory popular in the
Victorian Age, which proposed that evolving life forms moved logically and
inevitably along a ladder of progress towards the development of the highest form of life. Instead, the evidence of the shale is
that an astonishing diversity of life, much of it now extinct, was subject
to random accidents and dangers, and only sheer chance has made homo sapiens the dominant life form
on Earth today.
Burgess Shale:
Evolution's Big Bang is a traveling exhibition from the Department of
Paleobiology, National Museum of Natural History, Smithsonian
Institution. It is one of the Smithsonian
Institution Traveling Exhibition Service (SITES) programs, which share the
treasures of the Smithsonian with the general public.
Earth Explorers and the Silk
Road --Lectures and Travel
March
and April are busy months for the "Earth Explorer" lecture series
at the museum. In addition a second presentation about the famous Silk Road region in China will be given.
Thursday, March 7
The Silk Road: A Cradle of Primate and Human Evolution
Museum
scientist Chris Beard, whose expeditions have uncovered exciting new fossil
primates along the Silk
Road, talks about
northwest China as an important crucible of evolution. Museum of Art
Theater, 7 pm. members/students/seniors $5; nonmembers, $8.
Travel to the Silk
Road yourself! The museum is sponsoring a
trip from September 17 to October 3, 2002. For
information contact Barbara MacQuown, 412.578.2618.
Thursday,
March 14 Exploring
Active Volcanoes: What can be learned from an often deadly field-based
science? Dr. Michael Ramsey
of the Department of Geology and Planetary Science, University of Pittsburgh, shares his experiences and research in this
often risky and hazardous profession.
7 pm, Carnegie Museum of Art Theater. Free..
Thursday, March 21 Earth's Early Atmosphere and Climate. Dr. James
Kasting, Professor of Geosciences Meterology, ESSC, Pennsylvania State
Univbersity, explains the evolution of Earth's atmosphere, the Snowball
Earth episodes that triggered global glaciations, and how organisms and
early life survived. 7pm, Carnegie Museum of Art
theater. Free.
Saturday, March 23 The
Cambrian Explosion: Exploring the Burgess Shale
Join
Invertebrate Paleontology collection manager Albert Kollar for a look at
the exhibit The Burgess Shale:
Evolution's Big Bang, and see the museum's own collection. Workshop 9 am to 1 pm, Orange Classroom, members/students/seniors
$5; nonmembers, $8.
Saturday, April 6 Clues from Crocodiles Dr.
Mary Dawson, the museum's curator of Vertebrate Paleontology, gives an
expert look at the millions of years following the extinction of the
dinosaurs, as portrayed in When
Crocodiles Ruled, now at the museum.
members/students/seniors $5; nonmembers, $8.
Thursday,
April 11 Time Traveler: The Search for dinosaurs and ancient mammals from Montana and Mongolia. A lecture and book signing by Dr. Michael
Novacek, curator of Vertebrate Paleontology at American Museum of Natural
History, looks back on his life--the trials and events of a career that took him to every continent
in the world and the discovery of fabulous fossils of mammals and
dinosaurs. 7 pm, Carnegie Museum of Art Theater. Free.
The Earth Explorer Lecture Series is co-sponsored by
CMNH, the Department of Geology and Planetary Science of the University of Pittsburgh, and the National Science
Foundation.
Tim
Pearce--New Curator of Malacology
Tim Pearce, former curator of Mollusks, Delaware Museum
of Natural History, has joining the scientific staff of Carnegie Museum of
Natural History as the new curator of Malacology, which most of us know as
shellfish, and snails. "Malacology" comes from the Latin for
"soft" (mollis) and is
the study of all those soft-bodied, backboneless creatures that have
inhabited the earth for hundreds of millions of years, and often protected
themselves with hard shells.
The museum has an important collection of approximately
three million shells which, when combined with the fossil
examples in Invertebrate Paleontology, make a scientific resource of about 3.5
million specimens. For the last 20 years the shell collection has been kept
active and maintained by dedicated volunteers and supportive museum
scientists. There have been
arrangements for donations, loans, and scientific visitors, but no
full-time curator.
Tim Pearce, as an experienced and well-published expert
on mollusks, will give the collection higher visibility as a resource of
Carnegie Museum of Natural History.
After completing current research on the biogeography of land
snails, he expects to research the distribution of land snails of Western
Pennsylvania, and produce an atlas of value to agricultural managers interested invasive species, and to
conservationists and nature enthusiasts interested in native and rare
species.
As with other scientific collections, a computerized
data base and organization of the material in new cases such as metal
compactors (which allow great economy of space) would bring the collection
up to the high standard of accessibility and preservation that other research
collections now have. Pearce says he
is "looking forward to having so many scientific colleagues in the same
building, and to being part of a vibrant academic community in Oakland that
includes both museum and university experts."
Tinysaurus
When Discover magazine (January, 2002)
highlighted the top scientific discoveries for the year 2001, it included
the tiny mammal Hadrocodium wui,
which was scientifically described by Dr. Zhe-Xi Luo, associate curator of
vertebrate paleontology at Carnegie Museum of Natural History. Weighing no more than a paperclip, this
tiny shrew-like creature scurried amid Jurassic-era dinosaurs 195 million
years ago. Hadrocodium had a big brain and a tiny body. But, Luo points out, the big brain did not mean the animal was
particularly bright, since, "Mammals, even tiny ones, need big brains
just to coordinate all their bodily systems."
Dance to the Fossil Record
To
accompany the museum’s current exhibit on the Burgess Shale, the Museum of Natural History Store is offering a book titled Planet Ocean: Dancing to the Fossil Record by Brad Matsen and
Ray Troll. Writer Matsen and
illustrator Troll combine their skills with a playful sense of humor as
they journey through the fossil record in this engaging and entertaining history
of evolution suitable for teens through adults.
|
