Friday, November 23, 2012

Archaeopteryx might have just been dethroned by a new found fossil of Xiaotingia zhengi (adjacent pic, artist's impression)

Since its discovery in 1861, Archaeopteryx has been viewed as the iconic evolutionary link between dinosaurs and birds. But now the centrality of Archaeopteryx in the transition from dinosaur to birds is challenged. The 155-million-year old, chicken sized fossil of Xionting
ia zhengia found in 2011 in China suggest strongly that Archaeopteryx was indeed not so closer to birds after all, and now it has been removed from the avialian category and placed (along with Xiaotingia zhengi) in the category of deinonychosaurs, which has many birdlike dinosaurs. Basically meaning that Archaeopteryx may be only a birdlike dinosaur rather than a dinosaurlike true bird (Source 6).

Since the past 2 decades, the seemingly uniquely birdlike characteristics of Archaeopteryx, such as feathers, a wishbone and a three-fingered hand, have become a lot less unique.
A lot of dinosaurs with feathers and wishbone have been discovered in the recent past, resulting in the gradual erosion of the avian status of Archaeopteryx.

This has directly made the pigeon-size feathered creature known as Epidexipteryx hui recently discovered in Inner Mongolia, China, as the earliest known avialan in the category (Source 4).

"As we try to tease apart what's going on, we're left with slight differences between species, and each new find reshuffles the deck. Xiaotingia might have moved Archaeopteryx out of the birds, but the next find could move it back into birds or somewhere else. That's how it should be, how science works, new evidence changes our conclusions." said Lawrence Witmer, anatomist and paleontologist at Ohio University. (Source 2, from livescience.com)

Source:
1) Published: http://www.nature.com/nature/journal/v475/n7357/full/nature10288.html
2) http://www.livescience.com/15246-flap-flop-earth-bird-bird.html
3) http://www.the-scientist.com/?articles.view%2FarticleNo%2F30969%2Ftitle%2FOn-the-Origin-of-Birds%2F
4) http://www.livescience.com/2987-bird-dinosaur-sported-bizarre-tail-feathers.html
5) http://scienceblogs.com/pharyngula/2011/07/28/xiaotingia-zhengi/
6) http://www.nytimes.com/2011/08/02/science/02fossil.html?_r=0
Image credit: Xing Lida and Liu Yi
from: http://www.livescience.com/15246-flap-flop-earth-bird-bird.html
Archaeopteryx might have just been dethroned by a new found fossil of Xiaotingia zhengi (adjacent pic, artist's impression) 

Since its discovery in 1861, Archaeopteryx has been viewed as the iconic evolutionary link between dinosaurs and birds. But now the centrality of Archaeopteryx in the transition from dinosaur to birds is challenged. The 155-million-year old, chicken sized fossil of Xiontingia zhengia found in 2011 in China suggest strongly that Archaeopteryx was indeed not so closer to birds after all, and now it has been removed from the avialian category and placed (along with Xiaotingia zhengi) in the category of deinonychosaurs, which has many birdlike dinosaurs. Basically meaning that Archaeopteryx may be only a birdlike dinosaur rather than a dinosaurlike true bird (Source 6).  

Since the past 2 decades, the seemingly uniquely birdlike characteristics of Archaeopteryx, such as feathers, a wishbone and a three-fingered hand, have become a lot less unique. 
A lot of dinosaurs with feathers and wishbone have been discovered in the recent past, resulting in the gradual erosion of the avian status of Archaeopteryx.

This has directly made the pigeon-size feathered creature known as Epidexipteryx hui recently discovered in Inner Mongolia, China, as the earliest known avialan in the category (Source 4).

"As we try to tease apart what's going on, we're left with slight differences between species, and each new find reshuffles the deck. Xiaotingia might have moved Archaeopteryx out of the birds, but the next find could move it back into birds or somewhere else. That's how it should be, how science works, new evidence changes our conclusions." said Lawrence Witmer, anatomist and paleontologist at Ohio University. (Source 2, from livescience.com)

Source:
1) Published: http://www.nature.com/nature/journal/v475/n7357/full/nature10288.html
2) http://www.livescience.com/15246-flap-flop-earth-bird-bird.html
3) http://www.the-scientist.com/?articles.view/articleNo/30969/title/On-the-Origin-of-Birds/
4) http://www.livescience.com/2987-bird-dinosaur-sported-bizarre-tail-feathers.html
5) http://scienceblogs.com/pharyngula/2011/07/28/xiaotingia-zhengi/
6) http://www.nytimes.com/2011/08/02/science/02fossil.html?_r=0
Image credit: Xing Lida and Liu Yi
from: http://www.livescience.com/15246-flap-flop-earth-bird-bird.html

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