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Newly discovered fossils from China
shed light on common ancestry of
monkeys, apes and humans
- DEKALB, Ill.For the first time, scientists have discovered
skeletal parts of an extinct primate that documents an early
phase in the evolution of monkeys, apes, and humans.
- In an article published today in the prestigious British
journal Nature, the team of American and Chinese paleontologists
describe fossilized foot bones of Eosimias, an early higher
primate that lived about 45 million years ago in China.
- "We have the first unambiguous evidence that is able
to bridge the anatomical gap between lower and higher primates,"
said paleontologist Dan Gebo, a professor of anthropology
at Northern Illinois University and lead author of the Nature
- Gebos co-authors are Marian Dagosto of Northwestern
University Medical School in Chicago; K. Christopher Beard
of Carnegie Museum of Natural History in Pittsburgh; and Qi
Tao and Wang Jingwen of the Institute of Vertebrate
Paleontology and Paleoanthropology in Beijing.
- Previously, paleontologists
had found only jaws and teeth of Eosimias, a primitive tree-dwelling
primate about the size of the smallest living monkeys. Because
of the scanty anatomical evidence available for Eosimias prior
to todays report, leading paleoanthropologists had been
divided on the issue of exactly where Eosimias fits on the
primate family tree.
- Some prominent scientists even doubted that Eosimias was
a primate at all. But the new evidence, consisting of multiple
ankle bones from sites in central and eastern China, confirms
that Eosimias is a very primitive member of the lineage that
today includes monkeys, apes and humans.
- "The most interesting aspect of these new foot bones
is that they represent a mosaic," Gebo said. "They
possess primitive lower-primate features as well as several
advanced or higher-primate characteristics. No other fossil
primate in the Eocene has this interesting combination."
- Co-author Christopher Beard said the latest discovery is
important because it helps fill a major gap in the fossil
record of humans and their nearest relatives.
- "I hate to use the term missing link because
its such a cliche, but these fossils really do fill
a wide gap that previously separated higher primates, also
known as anthropoids, from their prosimian relatives,"
said Beard, who coordinates the American side of the joint
Sino-American expeditions that resulted in new fossil discoveries.
- Living anthropoids include monkeys, apes and humans. Living
prosimians include lemurs, bush babies, lorises and tarsiers.
The evolutionary origin of higher primates has stymied paleontologists
and primatologists for decades, because so little was known
regarding the ancestral anthropoid lineage until recently.
- Modern primates possess a variety of anatomical adaptations
for moving through their environment--usually the trunks and
branches of trees in tropical and subtropical forests. Many
prosimians are renowned for their ability to leap and cling
to vertical tree trunks, while monkeys tend to walk on all
fours on the tops of branches.
- The anatomy of the fossilized ankle bones of Eosimias show
that this animal
- already preferred walking quadrupedally on the tops of branches
like living monkeys.
- In addition to verifying that Eosimias is an early higher
primate, the new fossils help settle a longstanding debate
about where the anthropoid lineage arose on the primate family
- Previously, there were three main hypotheses regarding the
nearest relatives of anthropoids. Based on similarities in
the anatomy of their teeth, some scientists have argued that
anthropoids evolved from the lemur-like adapids. Genetic similarities
and the anatomy of living primates lead other scientists to
believe that living and fossil tarsiers are the nearest evolutionary
cousins of anthropoids.
- A third hypothesis accepts an evolutionary relationship
between anthropoids and tarsiers, but posits that the split
between these two lineages is very ancient, dating to at least
55 million years ago. The new ankle bones of Eosimias are
similar to those of anthropoids and fossil omomyids, a group
widely believed to be extinct relatives of tarsiers.
- "The oldest known skeletal remains of a higher primate
are inconsistent with the view that monkeys, apes and humans
evolved from the lemur-like adapids," Beard said, "but
they support a close evolutionary relationship between anthropoids
- Scientists recovered the fossils from a commercial limestone
quarry about 100 miles west of Shanghai and from a locality
in Shanxi Province (China), along the Yellow River, about
350 miles southeast of Beijing. The location of the discovery
also is significant, the researchers say.
- "Most scientists in my field believe that if the ancestor
of anthropoid primates is to be found then it should come
from Africa," Gebo said. "Thus, the bones of Eosimias
are important, as is its unusual location (Asia)."
- The new fossils were recovered during a series of expeditions
organized by scientists from Carnegie Museum of Natural History
in Pittsburgh, Pennsylvania and the Institute of Vertebrate
Paleontology & Paleoanthropology in Beijing.
- Nature article authors
- Daniel Gebo, Dept. of Anthropology
- Northern Illinois University, DeKalb, Ill.
- Tel: 815-753-0449
- Email: firstname.lastname@example.org
- Marian Dagosto, Dept. of Cell and Molecular Biology
- Northwestern University Medical School, Chicago, Ill.
- Tel: 312-503-9215
- email: email@example.com
- K. Christopher Beard, Section of Vertebrate Paleontology
- Carnegie Museum of Natural History.
- Tel: 412-622-5782
- Email: firstname.lastname@example.org
- Qi Tao and Wang Jingwen, Institute of Vertebrae Paleontology
and Paleoanthropology, Chinese Academy of Sciences, Beijing,
Peoples Republic of China.
- Eosimius illustration courtesy of Carnagie
Museum of Natural History, Pittsburgh.