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Fossil find lends an ear to science
Source: Xinhua |
October 10, 2009, Saturday
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Print Edition
Print Edition
AN international team of paleontologists has discovered a new species of mammal that lived 123 million years ago in what is now the Liaoning Province in northeastern China.
The animal, Maotherium asiaticus, comes from famous fossil-rich beds of the Yixian Formation. The remarkably well preserved fossil, a report in the current issue of the journal Science noted, offers an important insight into how the mammalian middle ear evolved.
"What is most surprising, and thus scientifically interesting, is this animal's ear," said Dr Zhe-Xi Luo, curator of vertebrate paleontology and associate director of science and research at Carnegie Museum of Natural History.
"Mammals have highly sensitive hearing, far better than the hearing capacity of all other vertebrates, and hearing is fundamental to the mammalian way of life. The mammalian ear evolution is important for understanding the origins of key mammalian adaptations."
Thanks to their intricate middle ear structure, mammals (including humans) have more sensitive hearing, discerning a wider range of sounds than other vertebrates. This sensitive hearing was a crucial adaptation, allowing mammals to be active when it was dark and to survive in the dinosaur-dominated Mesozoic era.
Mammalian hearing adaptation is made possible by a sophisticated middle ear of three tiny bones, known as the hammer (malleus), the anvil (incus), and the stirrup (stapes), plus a bony ring for the eardrum (tympanic membrane). These mammal middle ear bones evolved from the bones of the jaw hinge in their reptilian relatives.
Paleontologists have long attempted to understand the evolutionary pathway via which these precursor jawbones became separated from the jaw and moved into the middle ear of modern mammals.
To evolutionary biologists, an understanding of how the sophisticated and highly sensitive mammalian ear evolved may illuminate how a new and complex structure transforms through evolution.
Because Maotherium asiaticus was preserved three-dimensionally, paleontologists were able to reconstruct how the middle ear attached to the jaw.
The animal, Maotherium asiaticus, comes from famous fossil-rich beds of the Yixian Formation. The remarkably well preserved fossil, a report in the current issue of the journal Science noted, offers an important insight into how the mammalian middle ear evolved.
"What is most surprising, and thus scientifically interesting, is this animal's ear," said Dr Zhe-Xi Luo, curator of vertebrate paleontology and associate director of science and research at Carnegie Museum of Natural History.
"Mammals have highly sensitive hearing, far better than the hearing capacity of all other vertebrates, and hearing is fundamental to the mammalian way of life. The mammalian ear evolution is important for understanding the origins of key mammalian adaptations."
Thanks to their intricate middle ear structure, mammals (including humans) have more sensitive hearing, discerning a wider range of sounds than other vertebrates. This sensitive hearing was a crucial adaptation, allowing mammals to be active when it was dark and to survive in the dinosaur-dominated Mesozoic era.
Mammalian hearing adaptation is made possible by a sophisticated middle ear of three tiny bones, known as the hammer (malleus), the anvil (incus), and the stirrup (stapes), plus a bony ring for the eardrum (tympanic membrane). These mammal middle ear bones evolved from the bones of the jaw hinge in their reptilian relatives.
Paleontologists have long attempted to understand the evolutionary pathway via which these precursor jawbones became separated from the jaw and moved into the middle ear of modern mammals.
To evolutionary biologists, an understanding of how the sophisticated and highly sensitive mammalian ear evolved may illuminate how a new and complex structure transforms through evolution.
Because Maotherium asiaticus was preserved three-dimensionally, paleontologists were able to reconstruct how the middle ear attached to the jaw.
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