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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: To preempt the religious debaters...
By nengel on 4/18/2011 6:02:24 PM , Rating: 2
I very much agree with your post, and I don't think that the army of responders who came out against your very reasonable stance refuted what you were offering, which is really quite neutral in terms of metaphysical and theological commitments.

I have done little research into this area, some on either side, and am very interested in digging deeper. The stance I take would be similar to yours, that being if we find the naturalistic processes for which we can show the possibility and plausibility for the origin of life and subsequent change leading from single cell to multi-cellular to complex organisms, then I would absolutely accept it. Theistic evolution would sit just fine with me. This is really the open minded position to take, despite the objections. This approach would use information we HAVE to make an inference to the best explanation. Be it the origin of life or the massively finely-tuned universe that is needed to support it, the teleological argument has a lot of weight. Far from stopping science or positing God as a substitute for more explanation to current processes as we observe them, it is merely open to a non-naturalistic metaphysic, that if we see in nature what appears to be trademarks of design, so be it, follow the argument where it leads. A committed materialist cannot allow a divine foot in the door, but this is a metaphysical position, not a scientific position, in fact science can say nothing to it.

So I really don't mind evolution. I do get annoyed when it is the one theory you cannot criticize, at minimum it will allow a better theory to emerge when we understand it more fully, and isn't that the goal of the scientific enterprise? It certainly does not prove atheism, it would merely push back the question of why life, to why a finely tuned universe with minds to comprehend it rather than nothing at all? And God as proposed as a metaphysically ultimate starting point needs no other creator/designer, but matter, energy, time, and space do, if you accept contemporary cosmology.

I understand why evolutionists get angry at evolution deniers, there are some ridiculously bad arguments trotted out against it, even ones that have had no merit for a while. But there is a big difference from what I have seen between denying an old universe because the Bible says "days", and propounding problems for bio-genesis or the development of radically new organs from random mutation due to the specificity of biological information we now have. I try to be as un-dogmatic either way, we may really find all the processes needed for the formation of the first cell from simple organic compounds, but me may not, and I am also willing to look down that path.


By rbuszka on 4/18/2011 8:54:07 PM , Rating: 2
I'm thankful and encouraged that somebody actually understood the true point of my post above, instead of knee-jerking into "Gaaah, die, you Creationist!" mode like everyone else did. I'm also encouraged to see that my first respondent was rated down to '0', because the first three paragraphs of his post are three different textbook logical fallacies (that is, non-arguments).

My point was that evolution in any form can't be used as a religious-political tool to exclude God from participating in events on Earth, and that a theistic evolutionary worldview can provide someone with the freedom to be in harmony with both science and theistic faith. Really, it's only at odds with Genesis Chapter 1, which most English translations of the Bible render as poetry anyway, indicating that its source is actually a poem whose writer may have been taking artistic license in order to explain that God is the first cause of the universe. Yes, I know about Multiverse Theory, but that has not yet been shown to be a provable theory, and I don't subscribe to "if you can dream it you can do it" cosmology. However, I do recognize that my above statements would be very frustrating to those who want to use the success or usefulness (not necessarily the same things) of evolutionary theory to force a post-Enlightenment naturalistic worldview on other people, because it allows one's faith to sidestep the Evolution issue entirely.


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