標題: 研究者發現可能有原始羽毛結構的恐龍化石 [打印本頁]
作者:
oviraptor 時間: 2010-9-9 06:22 PM 標題: 研究者發現可能有原始羽毛結構的恐龍化石
新華網倫敦９月８日電（記者 黃堃）西班牙研究人員在新一期英國《自然》雜志上報告說，他們發現了一種奇特的恐龍化石，它的背上可能長了一個突出的肉冠，前腿骨上還有一排整齊的點狀突起，與現在鳥類羽毛根部的羽莖瘤非常相似，很可能是有原始羽毛結構的古老恐龍化石。
報告說，這具在西班牙中部地區發現的恐龍骨架化石保存完好。據分析這頭恐龍頭尾長約４米，生活在距今約１．３億年前。其前腿尺骨上有一排整齊的點狀突起，看起來很像現在鳥類羽毛根部的羽莖瘤。羽莖瘤是鳥類骨骼上長出飛行羽毛的結構，它將羽毛牢牢固定在骨骼上，對鳥類飛行能力具有重要作用。
研究人員指出，雖然以前在其他恐龍化石中發現過類似鳥類羽毛的結構，但此次發現的化石年代更早。
與其他已發現的恐龍不同，這種恐龍背上兩塊位置特殊的脊椎骨顯示，其背上應該長有一個突出的肉冠。研究人員目前還不清楚這個肉冠的作用，有觀點認為這與某些動物頭頂有炫耀作用的肉冠相似，但也有觀點認為它可能有更實際的作用，比如像大象的耳朵那樣扇風，或像駱駝的駝峰那樣儲存能量。
目前，生物學界關于鳥類的進化尚存很多疑問。一種著名理論認為，最早的鳥類是由長有羽毛的小型恐龍進化而來。
作者:
oviraptor 時間: 2010-9-9 06:24 PM 標題: 英文版補充!
Hump-backed dinosaur may yield clues to origin of birds
The dinosaur had a hump over its pelvis and attachment bumps for feathers on its forearms
Spanish palaeontologists have uncovered a new dinosaur with what may be the earliest evidence of feather follicles.
The researchers, whose findings are published in Nature, located the fossils near Cuenca, central Spain.
They named the reptile Concavenator corcovatus, meaning "meat eater from Cuenca with a hump". The type of dinosaur that was found is known as a theropod.
Theropods are mainly known from the ancient southern landmass, Gondwana.
Over time, Gondwana and other ancient landmasses broke up, forming the continents we see today.
Recently a team from Cambridge, UK, and the US showed that the theropods may have originated in the Northern landmass, Laurasia.
The most primitive forms have been found in England and now Spain. These finds date from the Lower Cretaceous, somewhere between 100 and 146 million years ago
Theropods are a very important group of dinosaurs because it is from this group that birds are known to originate. Most theropods, like the one found in Spain, are meat-eaters, though some were omnivores.
"They are a very important group of dinosaurs because within this group there are the birds. This world would not be the same without birds. Birds are really a kind of specialised winged and flying theropod dinosaur," said Professor Jose Sanz of the Universidad Autonoma de Madrid.
The dinosaur's unusual skeleton included a hump over the ilium - where the hind legs join the spine - and around five bumps on the forearm.
These bumps closely resemble the attachment points for feathers found in modern birds, and might present evidence that feathers are much older, in evolutionary terms, than previously thought.
The fossil dates from a time period when feathers or feather-like appendages have been seen, but the dinosaur is from a branch of the evolutionary tree that is more primitive.
Although these bumps have been seen in dinosaurs before - including Velociraptor, it is interesting and new to find this characteristic in a dinosaur that is so far removed from either birds or previous known feathered dinosaurs.
The bumps are very similar to those in present-day birds, with just two differences. There are fewer bumps in the Concavenator and they are not in such a regular arrangement.
The team interpret these differences in evolutionary terms. They suggest that over evolutionary time the bumps could have evolved into the feather attachments that are found in modern birds.
The hump found on the dinosaur's spine is more of a mystery, however. Humps are common in dinosaurs, and can be used for heat regulation - when they might look like a kind of sail - for display, or for food storage.
Five bumps were found on the fossil arm bones (top) whereas modern birds such as the turkey vulture (bottom) have eight to 10.
The scientists from Madrid uncovered the bones in Cuenca, central Spain
The team cannot work out what this hump might be for, though.
It is probably not for heat regulation, since normally a hump of this type would need an extensive blood supply, and there would be evidence within the surrounding bone - the team did not find this.
Also, most previous dinosaur humps have been found around the shoulders or the centre of the back - this hump is further towards the tail.
http://www.bbc.co.uk/news/science-environment-11221459
作者:
hunter-hunted 時間: 2010-9-11 06:49 PM
very strange dinosaurs
作者:
路人甲 時間: 2010-9-12 07:55 PM
But 侏羅紀後期左右已經出現了其他羽毛恐龍及鳥類，這個會算是起源嗎
作者:
megalodon 時間: 2010-9-14 04:15 PM
Wow!!!!!
作者:
oviraptor 時間: 2010-9-19 08:57 PM
QUOTE:
原帖由 路人甲 於 2010-9-12 07:55 PM 發表
But 侏羅紀後期左右已經出現了其他羽毛恐龍及鳥類，這個會算是起源嗎
牠未必是真的羽毛起源，但可以証明原始羽毛是從恐龍身上開始發展
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