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 newly discovered animal, Maotherium asiaticus, comes from famous fossil-rich beds of the Yixian Formation. This new remarkably well preserved fossil, as reported in the October 9 issue of the prestigious journal Science, offers an important insight into how the mammalian middle ear evolved.
The discoveries of such exquisite dinosaur-age mammals from China provide developmental biologists and paleontologists with evidence of how developmental mechanisms have impacted the morphological (body-structure) evolution of the earliest mammals and sheds light on how complex structures can arise in evolution because of changes in developmental pathways.
"What is most surprising, and thus scientifically interesting, is this animal's ear," says 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 in the darkness of the night and to survive in the dinosaur-dominated Mesozoic.
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. According to the Chinese and American scientists who studied this new mammal, the middle ear bones of Maotherium are partly similar to those of modern mammals; but Maotherium's middle ear has an unusual connection to the lower jaw that is unlike that of adult modern mammals. This middle ear connection, also known as the ossified Meckel's cartilage, resembles the embryonic condition of living mammals and the primitive middle ear of pre-mammalian ancestors.
Maotherium asiaticus is a symmetrodont, meaning that it has teeth with symmetrically arranged cusps specialized for feeding on insects and worms. It lived on the ground and had a body 15 cm (5 inches) long and weighing approximately 70 to 80 grams (.15 to .17 lbs). By studying all features in this exquisitely preserved fossil, researchers believe Maotherium to be more closely related to marsupials and placentals than to monotremes—primitive egg-laying mammals of Australia and New Guinea such as the platypus.
The article in Science is authored by Dr. Qiang Ji of Chinese Academy of Geological Sciences (Beijing), Dr. Zhe-Xi Luo (Carnegie Museum of Natural History) and Mr. Xinliang Zhang (Henan Provincial Geological Museum), along with other collaborators.
The researchers received support from National Science Foundation (USA), National Natural Science Foundation (China), Ministry of Science and Technology (China), and National Geographic Society.Additional information is available by contacting:
Images available at: http://www.carnegiemnh.org/news/09-oct-dec/100909maotherium-media.htm
Carnegie Museum of Natural History, one of the four Carnegie Museums of Pittsburgh, is ranked as one of the top five natural history museums in the country. It maintains, preserves, and interprets an extraordinary collection of 20 million objects and scientific specimens used to broaden understanding of evolution, conservation, and biodiversity.
Ice cave in Transylvania yields window into region's past
28.04.2017 | National Science Foundation
Citizen science campaign to aid disaster response
28.04.2017 | International Institute for Applied Systems Analysis (IIASA)
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
28.04.2017 | Event News
20.04.2017 | Event News
18.04.2017 | Event News
28.04.2017 | Medical Engineering
28.04.2017 | Earth Sciences
28.04.2017 | Life Sciences