Contact: Leigh Kish (412) 622-3361
New mammal from the Late Middle Eocene sheds light on the relationships
of early even-toed ungulates
An international team of researchers led by Carnegie Museum of Natural
History paleontologist Mary Dawson has discovered the first record of
a primitive artiodactyl (even-toed ) herbivore. This new genus of mammal
suggests that an early evolutionary split of artidactyls led to the
living mouse deer and their extinct relatives on the one hand and the
ruminant (cud-chewing) artiodactyls on the other.
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In an article published in the Journal of Mammalian Evolution (Volume
7, No. 4), the team of American and Chinese paleontologists describe
the new artiodactyl as Zhailimeryxjingweni. The discovery may
have widespread implications as scientists plot out the evolutionary
family tree of even-toed animals such as camels, deer and giraffes.
"Prior to the discovery of Zhailimeryx, scientists had difficulty
determining how modern day artidactyls were related," said Dr.
Dawson. "The dental characteristics of Zhailimeryx indicate
that the mouse deer and their relatives can be traced back as a separate
lineage to at least 40 million years ago in the Middle Eocene."
Zhailimeryx is one of the earliest distant and extinct relative
to mammals such as giraffes, camels and deer. It is more closely related
to the mouse deer of the tropics than the larger herbivores of Europe,
Asia, Africa and North America.
Zhailimeryx co-existed in the Middle Eocene with early rhinos,
primates, early dog-like carnivores, numerous rodents, and lizards.
It probably browsed on soft vegetation and plants that grew in marshy
areas. Scientists recovered the fossils from a small quarry in southern
Shanxi Province (China), along the Yellow River, about 350 miles southeast
of Beijing. This site has yielded numerous fossils including the primate
Eosimias, which bridges the evolutionary gap between early and
The discovery also and extends the geographic boundary of these now
"The species only existed in Asia during the Middle Eocene,"
added Dr. Dawson. "Its later relatives expanded in to Europe about
5 million years later when the Turgai Strait, which acted as a natural
barrier, dried up."
Dr. Dawson's research team included K. Christopher Beard of Carnegie
Museum of Natural History and Jianwei Guo, Jingwen Wang, Yongsheng Tong,
and Xhishi Huang of the Institute of Vertebrate Paleontology and Paleoanthropology,
Chinese Academy of Sciences.
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