 |
- Contact: Tom Parisi
- NIU Public Affairs
- (815) 753-3635
|
|
- Notes to media:
-
- 1) The research team’s paper to be published
in the Journal of Human Evolution can be accessed beginning
March 16 at: http://www.academicpress.com/jhevol
-
- Researchers discover fossils
- of tiny, thumb-length primates
-
 DEKALB, Ill.—A
team of researchers led by Northern Illinois University paleontologist
Dan Gebo has discovered the fossils of 45 million-year-old, thumb-length
primates.
-
- Recovered from the fissure-filled sediments of a limestone
quarry in China in 1996, the fossils easily represent the smallest
known primates, with one species estimated to have weighed only
10 grams. These distant relatives of monkeys, apes and humans
were once the prey of owls, the researchers say.
-
- The discovery of the smallest primates may have widespread
implications as scientists plot out the evolutionary family tree
leading from lower to higher primates. Living lower primates,
also known as prosimians, include lemurs and tarsiers. Living
higher primates include monkeys, apes and humans.
-
- "Few would have predicted such a diminutive monkey-like
creature at such a key branch of evolution," said Gebo,
a professor of anthropology at NIU. "These are the smallest
primates ever discovered, alive or extinct. Some of these fossils
are one-third the size of the living mouse lemur from Madagascar,
which at one ounce (31 grams) is the smallest known primate."
-
- Gebo’s research team includes Marian Dagosto of Northwestern
University Medical School in Chicago; K. Christopher Beard of
Carnegie Museum of Natural History in Pittsburgh; and Qi Tao
of the Institute of Vertebrate Paleontology and Paleoanthropology
in Beijing.
-
- Writing in the April edition of the Journal of Human Evolution
(London), the team reports on two of the tiny primate fossils.
- Estimated to have weighed 15 grams, the larger species is
believed to have been a higher primate belonging to the extinct
family Eosimiidae.
-
- "Both of the fossils are related to a branch of primate
evolution that eventually leads to humans," Gebo said.
-
- Primates are mammals, characterized by having bigger brains,
grasping hands and feet, nails instead of claws and eyes located
in the front of the skull. Hundreds of animal fossils, including
those of at least three minute primate species, have been culled
from a commercial limestone quarry 100 miles west of Shanghai.
-
- "The limestone itself is of Triassic age—from the
very beginning of the Age of Dinosaurs some 220 million years
ago," researcher Christopher Beard said.
-
- "The chemical composition of limestone makes this rock
dissolve easily in rainwater, leading to the creation of numerous
small fissures or limestone caverns that are often much younger
than the original limestone itself," Beard added. "As
chance would have it, the Triassic limestone in the quarry near
Shanghai is crisscrossed by fissures dating to the middle Eocene
(some 45 million years ago), in the middle of the interval in
which a poorly known lineage of higher primates must have existed."
-
- During the middle Eocene, a rainforest occupied the site.
However, unlike other prehistoric forests across the globe that
had a mix of large and small primates, the Shanghuang rainforest’s
fossil record is nearly absent of the larger creatures.
-
- "There is no place that mirrors what we’re finding
in China," Gebo said. "Other forests in the past have
had a few smaller species but they also had lots of big creatures."
-
- According to Beard, "The fact that we are sampling a
whole radiation of tiny primates at these Chinese sites indicates
for the first time that we are glimpsing a part of the evolutionary
tree of primates that previously eluded paleontologists."
-
- The researchers have no complete skeletons but as many as
50 foot bones belonging to primates weighing less than 100 grams.
Markings on the fossils have led the researchers to believe the
primates were once the prey of owls.
-
- Researcher Marian Dagosto discovered the heel bone of the
smallest primate as she sifted through a cardboard box filled
with matrix retrieved from the site and processed at the Institute
of Vertebrate Paleontology and Paleoanthropology in Beijing.
-
- Both Gebo and Dagosto, who in addition to being research
partners are husband and wife, are experts in identifying foot
bones.
-
- "We had literally thousands of bones from all sorts
of animals," Dagosto said. "It’s usually a matter
of going through them one by one. I found the primate heel bone
in the corner of the box, almost under the paper lining. Once
I realized just how tiny it was, it did strike me as really odd.
I remember calling Dan over right away."
-
- Dagosto said the researchers used a statistical technique
called regression, comparing the bone size with living animals,
to estimate the primate’s size and weight.
-
- The researchers say the tiny primates were tree dwellers
that relied on a steady diet of insects, fruit and nectar to
fuel their high metabolisms. Unlike contemporary higher primates,
the tiny primates likely were nocturnal and solitary creatures.
-
- "The implication is staggering," Gebo said. "You
would think that early higher primates would have a lot of characteristics
of later higher primates, which were social creatures that occupied
a daytime niche. It probably means we’re getting close to
the transition between higher and lower primates."
-
- Calling the China site a treasure trove of fossils, the researchers
added that 90 percent of the recovered specimens have not yet
been analyzed.
-
- —30—
-
- (See next page for a list of research authors.)
-
- Journal of Human Evolution article authors
-
- Daniel Gebo, Dept. of Anthropology
- Northern Illinois University, DeKalb, Ill.
- Tel: 815-753-0449
- Email: dgebo@niu.edu
-
- Marian Dagosto, Dept. of Cell and Molecular Biology
- Northwestern University Medical School, Chicago, Ill.
- Tel: 312-503-9215
- email: m-dagosto@nwu.edu
-
- K. Christopher Beard, Section of Vertebrate Paleontology
- Carnegie Museum of Natural History.
- Tel: 412-622-5782
- Email: eosimias@alphaclp.clpgh.org
-
- Qi Tao, Institute of Vertebrae Paleontology and Paleoanthropology
- Chinese Academy of Sciences, Beijing, People’s Republic
of China.
|
 |
|
