http://casemed.case.edu
Does new fossil link Homo erectus and Homo sapiens?
CLEVELAND (April 2006) – Case Western Reserve
University paleontologist Scott Simpson, Ph.D., began to relax, Feb. 16, after
a day of exploration in the Gona area in
For
the field scientist hunting for the fossils of our human ancestors, the ruckus
meant one thing—a big and important find.
Not
usually given to great displays of emotions, Jay Quade—the geologist for Gona
Paleoanthropological Research Project and from the
Inside
were fossils found by Asahamed Humet, a local nomadic pastoralist and longtime
member of the field team.
Humet’s
dedication and keen knowledge of the landscape, along with what Simpson
describes as a sixth sense for knowing where to find fossils, has led the field
team to some of their most important discoveries.
Quade
teased Simpson as he opened the smallest bag first containing a tooth, then
another with part of an upper jaw, then another and another until the pieces
formed nearly complete hominid skull.
Scott, a professor of anatomy in the Case Western Reserve
University School of Medicine who has a secondary appointment in anthropology
in the College of Arts and Sciences, has intensely studied many of few, and
very rare, hominid fossil skulls. He also has found hominid remains as old as
4.5 million years old (reported Nature
in 2005; see http://www.nature.com/nature/journal/v433/n7023/index.html).
He knew immediately by the anatomical shape of the new cranium
that this fossil, dating from 200,000 to 500,000 years ago, provided
significant information about the transition time between Homo erectus and Homo sapien, the rise of modern man.
The project’s principal investigator and archeologist, Sileshi
Semaw, from the Stone Age Institute of Indiana University, along with Simpson,
Quade, Humet and others returned to the site the next day. On hands and knees
and shoulder-to-shoulder, they crawled across a 50-foot square area in search
of any missing pieces. None were found. Assisting them was Case alumna
Stephanie Melillo (B.A., Anthropology 2005), who served as Simpson’s field
assistant.
Normally, news about important finds is
kept quiet until reported in major science journals. This time, according to
Simpson, the excitement was so high. “We’re like proud parents and wanted to
share the news with everyone,” he said.
Further research on the teeth along with sediment samples will
refine the age within that 300,000-year time span.
Through analyses of the material, Simpson and the team will
reconstruct a picture of life for this hominid. Because of isotopes of carbon
left in the enamel of the teeth along with those found in the sediments, they
will be able to determine whether this was grassland, forests or a mixture of
forests and grasses.
Along with the skull, they discovered early stone tools and the
fossils of large animals. One surprise was a large number of microfossils of
rats, mice and shrews in this sediment layer that has led them to believe that
barn owls lived there once—even though there is no fossil evidence. The
researchers can tell by broken fossil bones how they died and what might have
eaten them.
Also this amazing quantity of rodent fossils is found at scattered
sites of the research project in the same age layer of sediment. Simpson said
this requires further study.
The Gona area, a site assigned by the Ethiopian government for
this team’s research, has proven to be one of the most age diverse regions for
paleontology, said Simpson. The site’s time span ranges from 10,000 to 5.6
million years old.
“Our project differs from others in that
we can look at the major behavioral and technological changes over this wide
span of time,” explained Simpson.
Since the field team has arrived at the site in 1999, it has
yielded many historic treasures due to its location. The exploration is being
done at the geologically active intersection of three junctions in the Great
Rift, where
As the land shifts and separates, the earth’s crust thins out and
dips where water collects in lakes that have attracted animals and man’s
ancestors. Sediment also washes off the sides of hills and cliffs to collect
downstream.
Over time, erosion and faults expose the fossils that are found by
patient observation of the landscape that may take countless, and sometime,
fruitless of hours of scanning.
The Gona Project collects all hominid and monkey skeletal bones
and teeth found. They also gather the skulls of the large animals, foot bones
of antelopes and pigs (another research interest for Simpson). Sometimes photos
are taken of large animals like elephants and hippos.
“These fossils are a time machine,” said Simpson. “It is the only
direct evidence we have of what was our past.”
To read more about Simpson’s research, see http://cerebrum.case.edu/newsrelease/Simpson2.htm.
Also see http://cerebrum.case.edu/newsrelease/Simpson3.htm.
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