Print 53 comment(s) - last by callofduty1000.. on Apr 22 at 1:27 PM

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.

Comments     Threshold

This article is over a month old, voting and posting comments is disabled

RE: Why Bother?
By LRonaldHubbs on 4/18/2011 4:05:59 PM , Rating: 1
A tenuous connection?
lacking a sound basis, as reasoning; unsubstantiated

The fossil record is a major component of the theory of evolution. Any fossil, especially a fossil which is a new, transitional specimen like this one, is absolutely connected to the theory of evolution. This article didn't use any baiting or weasel words; it simply presented the information. Any flaming which occurs on this page is introduced by users, not by the article.

What’s next, you’ll print a highbrow article about how humans used to have spiny penises…?

The whole point of that article was that humans evolved to not have spiny penises. Any ancestor of humans which had a spiny penis was just that, an ancestor, not a human.

RE: Why Bother?
By Suntan on 4/18/2011 4:36:32 PM , Rating: 1
The whole point of that article was that humans evolved to not have spiny penises. Any ancestor of humans which had a spiny penis was just that, an ancestor, not a human.

The point of my post was to call out the absurdity of running an article about spiny penises... Not to question the mechanics of evolution.

I happen to believe in evolution, however I get tired of reading endless articles about obscure references to it for the sake of bringing out the Bible Thumpers on one hand, and the folk that like to use the term “Occam’s Razor” on the other.

The article here doesn’t even go into a discussion of these bones, or even give a picture of these bones, showing what they look like in this early mammal. Further, there is little to no effort to put it into a chronological context. Read the one source article (the one link that doesn’t point to a lot of other sensationalistic Dailytech evolution posts) that all of this article was cribbed from gives a better understanding. But a true understanding of this article isn’t needed. Just a good ol’ reference or two to evolution and then the arguments will get going in the discussion section…

…I also happened to notice that there has yet to be a single comment posted actually discussing the *topic* of this article… Coincidence?


RE: Why Bother?
By Skywalker123 on 4/18/11, Rating: 0
RE: Why Bother?
By Kurz on 4/19/2011 9:14:15 AM , Rating: 1
Dont read the comments?

"If a man really wants to make a million dollars, the best way would be to start his own religion." -- Scientology founder L. Ron. Hubbard

Most Popular ArticlesSmartphone Screen Protectors – What To Look For
September 21, 2016, 9:33 AM
UN Meeting to Tackle Antimicrobial Resistance
September 21, 2016, 9:52 AM
Walmart may get "Robot Shopping Carts?"
September 17, 2016, 6:01 AM
5 Cases for iPhone 7 and 7 iPhone Plus
September 18, 2016, 10:08 AM
Update: Problem-Free Galaxy Note7s CPSC Approved
September 22, 2016, 5:30 AM

Copyright 2016 DailyTech LLC. - RSS Feed | Advertise | About Us | Ethics | FAQ | Terms, Conditions & Privacy Information | Kristopher Kubicki