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Liaoconodon hui  (Source: Jin Meng)
A new fossil, Liaoconodon hui, was found in China and has all three middle ear bones

Researchers have discovered a complete mammalian fossil that includes a transitional middle ear, which consists of three bones that paleontologists have been searching for over 150 years.  

Jin Meng, study leader and curator in the Division of Paleontology at the American Museum of Natural History, along with Wang Yuanqing and Li Chuankui, both from the Institute of Vertebrate Paleontology and Paleoanthropology at the Chinese Academy of Sciences in Beijing, have found the first complete mammalian fossil that includes the transitional middle ear.

Mammals are defined as a class of air-breathing vertebrate animals that share characteristics like hair and mammary glands in mothers with young. They also share three middle ear bones called the malleus, incus and ectotympanic. Two of these bones are found in the joint of the lower jaw in reptiles, and researchers believe that an evolutionary shift from lizards to mammals separated the quadrate and articular plus prearticular bones from the posterior lower jaw, and they became associated with hearing as the malleus and the incus.

Previous fossils show early mammals with reptilian jaw joints and reductions in these bones for both chewing and hearing while other early mammalian fossils have ossified cartilage still connected to the groove on their lower jaws. But none of these fossils had the middle ear bones, and more evidence was needed to confirm this early transition and the mysteries of the mammalian middle ear. 

"People have been looking for this specimen for over 150 years since noticing a puzzling groove on the lower jaw of some early mammals," said Meng. "Now we have cartilage with ear bones attached, the first clear paleontological evidence showing relationships between the lower jaw and middle ear." 

The new fossil, which is called Liaoconodon hui, is a medium-sized mammal measuring 35.7 cm long. It dates from the Mesozoic (about 125 to 122 million years) and was named after the fossil beds in Liaoning, China, which is where it was discovered. It was also named after Yaoming Hu, who was a graduate of the American Museum of Natural History's doctoral program and passed away recently.  

Liaoconodon hui is complete, and shows researchers that the incus and malleus are detached from the lower jaw in order to create part of the middle ear. According to the study, the incus and the malleus "remain linked to the jaw by the ossified Meckel's cartilage that rests in the groove on the lower jaw," and the eardrum was stabilized with this cartilage as support. 

"Before we did not know the detailed morphology of how the bones of the middle ear detached, or the purpose of the ossified cartilage," said Meng. "Liaoconodon hui changes previous interpretations because we now know the detailed morphology of the transitional mammals and can propose that the ossified cartilage is a stabilizer."

This study also found that the middle ear "probably" evolved twice in monotremes, marsupials and placentals. This was determined by features associated with the groove on the lower jaw and other bones, including the presence of ossified Meckel's cartilage.  

This study was published in Nature.



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RE: Why Bother?
By JonnyDough on 4/19/2011 12:54:37 AM , Rating: 1
Radioactive material doesn't become inert over long periods of time either. I think I'm seeing a trend here...you seem to believe that the universe is static and not dynamic. I believe you are limiting yourself by not considering infinite possibilities in an unlimited universe.

Those who believe in God I ask this:

Why is it so hard to believe in an endless, timeless universe? Why do you feel compelled to believe in an endless timeless God with all the knowledge to create such a universe? Is that not just adding an additional and absolutely unprovable/illogically theorized complex layer on top of what we already see as truth? The universe exists. We both take that as fact. God exists, you rely on "belief, faith, emotion" and you take that as fact.

Which do we both concur on? It must be true. The universe exists.

So if we take that as a truth, then we must believe that within the universe there can come "intelligence" (ie creation, such as the birth of more humans) but can intelligence (ie creation) create a universe out of nothingness? Seems to be a farther stretch of my imagination...perhaps you and your God have powers that the average limited man doesn't have.

Why humans believe themselves to be some sort of demigods rather than animals I do not know. We are made of earth, and we rely on it for survival. If only more people realized we are not "above" nature. Last time I checked, a polar bear could eat things that you couldn't, survive places you couldn't, and kick your ass in a fist fight. So you have centuries of learning that you can borrow from and hold a gun in your hand. Big whoop. Human beings are not superior nature. They merely have a superior ability. It's time we start to understand that.


RE: Why Bother?
By Reclaimer77 on 4/19/11, Rating: 0
RE: Why Bother?
By LRonaldHubbs on 4/19/2011 8:07:20 AM , Rating: 1
If you don't believe in Creationism, and you also don't believe in evolution of species, then what exactly do you believe?


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