fossilshk | 2008-6-18 08:22 AM |
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科學家在加拿大發現7000萬年前新種恐龍化石 (中英/圖)
[img]http://www.fossilshk.com/forum_image/f686.jpg[/img]
據美國生活科學網報道,30多年前,一位探礦地質學家在加拿大卑詩省北部偶然發現一堆排列無序的遠古動物骨骼化石,目前,最新一項研究表明這些骨骼化石可能屬于一支新恐龍物種。
現共收集到了7塊胫骨、前肢骨和趾骨,還有1塊骨骼可能是頭骨碎片。基于這些骨骼的外形和大小,古生物學家認爲它可能屬于一種小型至中型恐龍物種,類似于腫頭龍或鳥腳亞目恐龍。目前,這一新物種恐龍被命名爲蘇斯圖特恐龍,其原因是這些恐龍骨骼發現于卑詩省中北部蘇斯圖特盆地。
1971年,探礦地質學家肯尼·拉森在野外勘探放射性金屬钍時,意外地發現一堆遠古動物骨骼,随後他從碎石中将這些松散的骨骼收集起來,2004年捐贈給加拿大達爾豪西大學。
大學生維多利亞·阿伯爾對這些骨骼進行了研究,他很快意識到這是一個罕見的考古發現——骨骼保存非常完好,是迄今卑詩省發現最完整的恐龍骨骼标本。然而拉森30多年前的最初挖掘地點已找不到,因此古生物學家并不知道骨骼發現的精确位置,很難确定該恐龍物種的生活年代。基于附着在骨骼上碎石的特性,阿伯爾和她的同學們認爲這一物種生活在0.7億年前白垩紀早期。
她發現這些骨骼碎片來自兩腿行走、食草性恐龍,其中一些骨骼類似于腫頭龍,這是一種兩腿奔跑恐龍,頭骨很薄、呈圓頂狀,另一些骨骼類似于鳥腳亞目恐龍,這是一種兩足食草性恐龍,長着角狀喙。
阿伯爾說,“蘇斯圖特恐龍兼具了兩種恐龍的特點,此外它的前肢是之前我們未曾發現過的。它應該是一支新物種,但是我們仍無法确定,目前需要發現更多的該物種骨骼化石。”該項研究報告強調稱,當前所發現的骨骼化石可能來自一隻恐龍,也可能來自該物種的多隻個體。
她将這項研究報告的詳細資料發表在近期出版的《加拿大地球科學》雜志上。目前,蘇斯圖特恐龍的骨骼化石收藏于卑詩省皇家博物館内。(13/06/2006) |
fossilshk | 2008-6-18 08:24 AM |
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New Canadian Dinosaur Largely Mysterious
[img]http://www.fossilshk.com/forum_image/f686.jpg[/img]
This composite shows what bones were found and what the Sustut dinosaur may have looked like 70 million years ago.
A prospecting geologist stumbled upon a ragtag bunch of bones in the northern part of British Columbia, more than three decades ago. A new study suggests these fossils could represent a new species of dinosaur.
But beyond that, the dinosaur's identity is a mystery - sort of a Dino Doe.
The small collection of bones includes seven shin, arm and toe bones, as well as a possible skull fragment. Based on the shapes and sizes of the bones, paleontologists think they could have belonged to a type of small- to medium-sized dinosaur, possibly a pachycephalosaur or ornithopod.
The specimen is referred to as the Sustut dinosaur, because it was found in the Sustut Basin in north-central British Columbia, Canada.
Kenny Larsen found the bones in 1971 while prospecting for thorium, a radioactive element. During his fieldwork, his instruments registered above-background levels of radiation, which turned out to be emitted by the bones. Larsen collected the loose bones from the rubble and held onto them until donating them to Dalhousie University in Halifax, Nova Scotia, in 2004.
The bones were studied by then-undergraduate student Victoria Arbour who soon realized the remains were a rare find: They are well-preserved and are the most complete dinosaur specimen found in British Columbia to date.
Larsen's original field notes were lost, so paleontologists don't know the exact location where the bones were found, making them harder to date. Based on properties of the rock attached to some of the fragments, Arbour and her colleagues think the specimen may date to about 70 million years ago in the Upper Cretaceous Period.
The bone fragments resemble those from a small two-legged, plant-eating dinosaur, Arbour found. Certain bones are similar to those from pachycephalosaurs, which ran on two legs and sported thick, dome-shaped skulls, while others are similar to ornithopods, bipedal grazers with horny beaks.
"There are similarities with two other kinds of dinosaurs although there's also an arm bone we've never seen before," Arbour said. "The Sustut dinosaur may be a new species, but we won't know for sure until more fossils can be found."
The bone fragments could possibly be from more than one individual, or even more than one type of dinosaur, the study notes.
Arbour's findings are detailed in the most recent issue of the Canadian Journal of Earth Sciences. Her research was funded by the Natural Sciences and Engineering Research Council of Canada and Alberta Ingenuity.
The fossils are currently in the collection of the Royal British Columbia Museum in Victoria, British Columbia.
(Yahoo 13/06/2006) |
Franco仔 | 2008-6-18 09:43 AM |
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中英對照,THX~~~~ |
bernizzz_fish | 2008-6-25 10:47 AM |
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為什麼從這麼少的骨頭都可以判斷出恐龍的種類? |
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恐龍主要分為蜥臀目和鳥臀目,當中也分很多的類別(參考[url]http://www.fossilshk.com/forum/viewthread.php?tid=1679&highlight=%E6%81%90%E9%BE%8D%E5%88%86)[/url]
[size=6]蜥臀目資料:[/size]
蜥臀目(學名Saurischia)也稱為龍盤目或蜥盤目。名稱源自希臘文中的σαυρος(sauros;「蜥蜴」之意)與ισχιον(ischion;「髖關節」之意)。是恐龍之下所屬兩目中的其中一目。
哈利·西列在1888年根據恐龍的骨盆結構,將恐龍分類成為兩大目,分別是蜥臀目與鳥臀目(Ornithischia)。兩者的差異在於蜥臀目的骨盆型態比較接近早期的恐龍。蜥臀目之下的獸腳亞目包含了所有的肉食性恐龍;而蜥腳形亞目則是龐大的草食性動物分支。
蜥臀目恐龍從三疊紀晚期開始出現,與鳥臀目支系分開個別演化,牠們所生存的時代一直延續到白堊紀結束為止。蜥臀目恐龍保有三叉的骨盆結構,恥骨往前;手部構造可以抓握,第二指加長[1];某些手盜龍類的先進物種改變骨盆結構,形成類似鳥臀目骨盆的平行排列。鳥臀目恐龍演化出新的臀部結構,恥骨往後轉到與坐骨平行,並有一個往前的突起,形成四叉的結構。這種臀部結構類似鳥的臀部結構,所以這群動物被命名為鳥臀目。
某些蜥臀目大約在侏儸紀時期演變成為鳥類的祖先(雖然鳥臀目也擁有類似鳥類的骨盆結構,但是這是趨同演化的結果)。
除了已經演變成為鳥類的分支之外,白堊紀晚期的白堊紀-第三紀滅絕事件使蜥臀目恐龍完全消失。
Seeley的分類經過時間的考驗,但羅伯特·巴克(Robert Bakker)在「The Dinosaur Heresies」一書中,將獸腳亞目獨立為個別的目,並將蜥腳形亞目與鳥臀目集合為一個目「Phytodinosauria」(植物恐龍)或是「Ornithischiformes」。
[img]http://upload.wikimedia.org/wikipedia/commons/thumb/8/8d/Saurischia.png/200px-Saurischia.png[/img]
[size=6]鳥臀目的資料:[/size]
鳥臀目(目名Ornithischia或Predentata)也稱為鳥盤目。是一類有喙(外觀類似鳥喙)的草食性恐龍。ornithischia之名源自希臘文中表示「鳥的」的ορνιθειος(ornitheos)與表示「髖關節」的ισχιον(ischion),意思是「如鳥類般的臀部」。之所以有這種名字,是因為牠們擁有與鳥類相似的臀骨結構。然而一般認為鳥類實際上是蜥臀目(Saurischia,「蜥蜴般的臀部」)的後代。
鳥臀目屬於草食性動物,有時群居。牠們數量比蜥臀目更多,是獸腳類(Theropoda)的獵物,且體型與蜥腳類相比較小。
[size=4]特徵[/size]
恐龍總目被Harry Seeley於1887年分為兩目:蜥臀目、鳥臀目。這種分法主要根據形狀類似鳥的骨盆(但是鳥類並非鳥臀目的後代)、脊椎骨的細節、以及是否擁有前齒骨。前齒骨是下顎前一塊從齒骨額外生長的骨頭,形狀為U形,在生前可能覆蓋者角質;而前齒骨後緣有溝槽,因此鳥臀目恐龍可轉動關節,以產生咀嚼食物的動作。[1]前齒骨與上顎的前上顎骨互相咬合。它們呈現類似鳥嘴的形狀,可以撕裂植物。
鳥臀目恐龍的恥骨(Pubis)分別指向前方與後方尾巴,往後與坐骨(Ischium)平行,與往前的突出部支撐者下腹部。使骨盆呈現一個四端分岔的結構。蜥臀目恐龍的恥骨則是別指向下方與前方,類似遠古蜥蜴那樣。鳥臀目恐龍眼窩前的洞比蜥臀目恐龍的小,但有較寬廣、穩定的骨盆。
類似鳥類的平行骨盆結構,在恐龍中分別、獨自演化出三次,分別為鳥臀目、鐮刀龍超科、以及馳龍科。
[img]http://upload.wikimedia.org/wikipedia/commons/thumb/e/eb/Ornithischia.png/250px-Ornithischia.png[/img] |
fossilshk | 2008-6-25 11:19 AM |
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[quote]原帖由 [i]bernizzz_fish[/i] 於 2008-6-25 06:47 PM 發表
為什麼從這麼少的骨頭都可以判斷出恐龍的種類? [/quote]
骨幹結構可分出種類,但另一半是側是猜想的 |
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