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標題: 河北省發現1.6億年前具有蝙蝠翅膀的小型恐龍  
 
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河北省發現1.6億年前具有蝙蝠翅膀的小型恐龍

河北省青龍縣侏羅系地層發現生活於約1.6億年前具有類似蝙蝠翅膀的小型恐龍——奇翼龍



  奇翼龍化石照片


  奇翼龍標本頭骨

  據中國科學院古脊椎動物與古人類研究所:鳥類及其恐龍近親的翅膀擁有一個共同特點:片狀飛羽是其關鍵組分,但珍藏于山東天宇自然博物館的一件來自我國河北青龍縣侏羅系地層的化石發現挑戰了這一認知。4月30日線上出版的英國《自然》雜誌上,由中國科學院古脊椎動物與古人類研究所徐星研究員和臨沂大學鄭曉廷教授帶領的一個科研團隊報導了一種生活於約1.6億年前的具有類似蝙蝠翅膀的小型恐龍,對於我們瞭解恐龍形態差異性和鳥類飛行起源研究具有重要意義,代表我國學者在鳥類起源研究方向取得的又一項重要成果。

  這種被命名為奇翼龍的小型恐龍屬於一個名叫擅攀鳥龍類的恐龍類群,這一類群與鳥類親緣關係非常近,但長相奇特,有著短粗的頭,手部外側手指極長,尤其是其僵硬的羽毛呈絲狀,更接近原始羽毛,而不像其他似鳥恐龍和鳥類擁有的片狀羽毛。最奇特的是奇翼龍腕部的一個棒狀長骨結構,類似結構從來沒有在其他恐龍當中發現過,但卻在一些會飛的四足動物的腕部,或者肘部,或者踝部附近存在,這些動物包括蝙蝠、翼龍和鼯鼠等,奇翼龍腕部的棒狀結構和日本鼯鼠腕部長著的棒狀結構尤其相像。在所有這些動物中,這種棒狀結構都支撐著翼膜,用於飛行或者滑翔。在奇翼龍標本上,研究者確實也在棒狀結構和手指附近發現了殘缺翼膜。這意味著奇翼龍有著和鳥類及其恐龍近親完全不同的翅膀,它的翅膀像蝙蝠和其他會飛的四足動物一樣,主要由翼膜構成,而不是像鳥類及其近親那樣主要由羽毛構成。

  徐星研究員介紹說,由於這件標本太過奇特,保存也不夠精美,研究者花費了很長時間才確認了這一結構。參與奇翼龍研究的古脊椎所加拿大籍副研究員舒克文博士介紹說“開始的時候,我們真的不知道這種棒狀骨結構是什麼,我因為另外一個完全不同的專案查閱有關飛翔和滑翔脊椎動物的科學文獻,碰巧在一篇文獻中看到這樣的章節,說鼯鼠具有一個棒狀的軟骨結構,與腕部或肘部關聯,支撐翼膜用以滑翔,隨後我在網路上發現的一個日本鼯鼠腕部棒狀結構的照片,顯示出和奇翼龍腕部棒狀結構驚人地相似,我立即告訴了徐星教授”

  為了揭示這一標本保存的重要資訊,尤其是確認這個棒狀結構的性質,徐星等採用了CT和掃描電鏡等多種儀器對化石進行分析,獲取了包括軟體組織上保存的黑色素體在內的宏觀和微觀資訊,還分析了化石圍岩和化石上的化學組分,最終確認了奇翼龍腕部的棒狀結構是翼膜翅膀的關鍵組成部分。

  鄭曉廷教授說:“有著翼膜翅膀的奇翼龍生活在侏羅紀中期,因此它算是在鳥類支系飛翔演化過程中的一個先鋒。它提醒我們,在飛翔演化的早期歷史中,充滿了創新嘗試,許多支系成為了演化的死胡同,只有現生鳥類的這種飛行模式延續至今。”

  值得一提的是,‘奇翼龍’是已知最短的恐龍名字。不僅如此,這個名字還凸顯了在恐龍向鳥類演化的過程中,這一物種演化出了一個非常奇特的翅膀,完全不同於其他似鳥恐龍和鳥類的翅膀。奇翼龍的發現,為翼膜狀飛行器官的趨同演化提供了一個絕佳實證,表明即便是在以羽翼為特徵的鳥類支系上,也曾出現過翼膜翅膀。

  儘管通過形態特徵的分析和飛行能力的計算,研究者相信奇翼龍的翅膀具有空氣動力學功能,但奇翼龍並不是一個具有競爭力的飛翔者,它的空中生活似乎只限于在樹木之間做短距離的飛翔,或者從高處飛翔到地面。研究者還無法確定奇翼龍是採用撲翼飛行,滑翔,還是二者兼具。最後一個方式極具可能性,但以前一直被從事鳥類飛行起源的研究者忽視,徐星認為這是未來探索的一個重要方向,奇翼龍可能以滑翔為主,輔助以撲翼飛行。

  徐星教授介紹說,很大程度上得益於中國似鳥恐龍和早期鳥類化石的大量發現,鳥類起源研究方向近年來取得了一系列重大進展,和人造探測器首次登陸彗星等一起,入選美國《科學》雜誌評選的2014年度世界10大科學突破。儘管如此,這一方向依然存在許多需要解答的問題,依然是目前古生物學和演化生物學的熱點研究方向。近年來,採用整合手段研究演化問題成為了學科新趨勢,許多學者從現生動物解剖學、生理學、發育生物學,乃至基因組學角度開始對鳥類起源問題展開了探討,取得了一批成果。我國需要加強各個學科交流,採用整合手段在鳥類起源方向展開更深入的研究,保持這一研究方向的領先優勢,推動更多相關問題的解決。

  參加本次研究工作的還有臨沂大學王孝理和王岩、中國地質大學(北京)的邢立達、天宇自然博物館的張曉梅、中科院古脊椎動物與古人類研究所的張福成和鄒晶梅與南京地質古生物研究所的泮燕紅。本項研究工作得到了中國國家自然科學基金委和科技部的資助。


奇翼龍的藝術復原圖




2015-4-30 07:38 AM#1
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fossilshk (Lung)
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Dinosaur with wings like a BAT found in China

Weird 'dinobat' discovered in China: Dinosaur with wings like a BAT may reveal clues about the origin of flight
-Yi qi is thought to have lived 160 million years ago during the late Jurassic
-The dinosaur has an unusual bone sticking out of its wrist and had a membrane that covered it to form a wing much like that of a modern bat
-Scientists say it is unlike any other dinosaur, which evolved into birds, and may have glided or even been able to fly by flapping over short distances
-The fossil was discovered by a farmer in Qinglong County in north China


A bizarre new dinosaur with bat-like wings has been discovered by a farmer in China and is now helping to shed new light on the evolution of flight.

Palaeontologists in China say the impeccably preserved fossil belongs to a small dinosaur thought to have lived 160 million years ago.

The strange-looking creature had small stiff feathers on its body and long finger-like bones extending from each wrist that were covered in a membrane like a bat’s wing.



The new dinosaur, named Yi qi (shown above in the artists reconstruction), had unusual bristle-like feathers and bat-like wings that were covered in a membrane. The dinosaur may have been able to glide and even flap


Scientists believe the dinosaur, which they have named Yi qi, meaning ‘strange wing’, may have glided or even flown through the air.The discovery has provided new insight into how vertebrates first began to take to the air.

Researchers say the dinosaur, which would have weighted just 13 ounces (380g), may have been an early evolutionary experiment with flight.

Yi qi belongs the group of carnivorous dinosaurs known as the therapods - which includes Tyranosaurus rex and velociraptor.

These dinosaurs are thought to have been the ancestors of modern birds.

But unlike modern birds, Yi qi was found to have a strange extra bone extending backwards from its wrist, rather like an entirely separate group of animals that learned to fly - the bats.

Professor Xing Xu, one of the world’s leading prolific palaeontologists at the Chinese Academy of Sciences in Beijing and who led the work, said: 'This is really something for me. It is the most unexpected discovery I ever made.

'Birds are descended from dinosaurs, but how exactly the transition occurred is not really clear. This new discovery is a new species of these bird like dinosaurs.

'This dinosaur is totally different. It has totally different wings from all other birds and their close relatives.

'Close to the origin of birds there are many lineages trying to get into the air but there was only one group that succeeded.

'I would have said this example shows how much experimentation close to this transition.'

The discovery comes in the same week as researchers announced the discovery of a bizarre vegetarian relative of the T-Rex.

The Yi qi fossil was discovered by a local farmer in Mutoudeng, in Qinglong County, Hebei Province in China.

The fossil has preserved stiff filamentous features on the forelimb and hindlimb, along with patches of the membrane that once stretched across its wings.

However, it was the strange wrists and long rod-like bones that extended from them that baffled the attention of the palaeontologists.

There are three main groups of flying vertebrates - the birds, which evolved from dinosaurs, pterosaurs that were flying reptiles that existed alongside the dinosarus, and the bats, which are mammals that evolved after the extinction of the dinosaurs 66 million years ago.

Most winged avian dinosaurs to be discovered so far all have wing structures that are similar to those of modern birds.

However, Yi qi, which is pronounced 'ee chee', appears to be a weird hybrid between a dinosaur and a bat.

This suggests that at the time several different types of winged dinosaurs evolved wings in an attempt to fly.





The fossil of Yi qi (above) was so well preserved that bristle-like feathers and the remains of its membrane wings could be seen around the bones. The strange long bone extending from the wrist was highly unusual




This close up of the skull of Yi qi, which weighed just 13 ounces (380g), show oval like feathers near the head




Analysis by Professor Xu and his colleagues, which is published in the journal Nature, suggest that it is likely the dinosaur glided, perhaps like modern flying squirrels.

The dinosaur lacked the strong muscle attachments to the forelimb bones and its bone structure would have interfered with the flapping and rotating movements needed during powered flight.

Instead it may have launched itself from elevated perches and glided to the ground. If it did flap its wings it would probably have only been able to fly over short distances.



But Professor Xu said: 'We thought giving this animal a name meaning "strange wing" was appropriate, because no other bird or dinosaur has a wing of the same kind

'We don’t know if Yi qi was flapping, or gliding, or both, but it definitely evolved a wing that is unique in the context of the transition from dinosaurs to birds.'

It is likely that the conclusions will be controversial with other evolutionary biologists, but it could prove hugely valuable in unravelling how birds evolved from their dinosaur ancestors.

Professor Zheng Xiaoting, from Linyi University in Shandong who also took part in the study, said: 'Yi qi lived in the Jurassic, so it was a pioneer in the evolution of flight on the line to birds.

'It reminds us that the early history of flight was full of innovations, not all of which survived.'

Dr Kevin Padian, a palaeontologist at the University of California Berkeley, warned that the animal may not have been able to fly at all.





The diagrams above show how  the wing of Yi qi (a) compares to other winged tetrapods (b and c) and the wing of a bat (d), the wing of a pigeon (e), the wing of a pterosaur (f) and the wing of a Japanese flying squirrel (g)




He said: ‘As for gliding, if Yi qi’s styliform element helped to support a membranous aerofoil, it can be used to reconstruct the planform of the wing, as Xu and colleagues have done.

‘But in a gliding animal, the centre of lift of the aerofoil should be fairly congruent with the centre of gravity of the body — if the bulk of the animal’s weight falls too far behind the centre of lift, the back end will sag and the animal will stall.

‘That is clearly the case in the authors’ reconstruction of Yi qi, but an aerofoil that was swept back more, if anatomically possible, might have mitigated this problem.

‘Still, we are left in a quandary: an animal with a strange structure that looks as if it could have been used in flight, borne by an animal that otherwise shows no such tendencies.

‘And so far, there is no other plausible explanation for the function of this structure.’

Read more:
http://www.nature.com/nature/jou ... ll/nature14423.html




2015-4-30 07:41 AM#2
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unknown12
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奇翼龍



Life finds a way.
2015-4-30 04:11 PM#3
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fossilshk (Lung)
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2015-4-30 09:06 PM#4
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rock-tw (馬英走~~)
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是不是帶羽毛的翼龍???
2015-5-1 05:45 PM#5
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unknown12
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QUOTE:
原帖由 rock-tw 於 2015-5-1 05:45 PM 發表
是不是帶羽毛的翼龍???
屬於theropod,不是翼龍




Life finds a way.
2015-5-2 10:58 PM#6
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