| hunter-hunted | 2009-4-22 08:59 AM |
|
中國嘉峪關發現霸王龍祖先化石-雄關龍
美國古生物學家在中國甘肅最新找到的一批化石，為霸王龍的進化過程提供了新的線索。 化石是在嘉峪關市附近發現的，被命名為雄關龍（Xiongguanlong baimoensis）。
霸王龍又叫暴龍。此前古生物學家們證實存在的暴龍屬品種只有雷克斯暴龍（Tyrannosaurus rex），因此通常不予區分。但這次找到的雄關龍很可能是暴龍屬的更早品種，也就是雷克斯暴龍的祖先。
這套雄關龍化石據信來自白堊紀中期，它的體型比雷克斯暴龍為小，但具備了後來的雷克斯暴龍身上能找到的一些體型特徵。
此前古生物學當中有關暴龍屬恐龍的知識建基於兩組來自白堊紀恐龍化石。白堊紀即距今約1.45億年至6500萬年間的時期。
這兩批化石當中，一批是來自早白堊紀的巴列姆階，另一批則來自巴列姆階之後幾千萬年。對於這兩個時期之間的關聯，科學家們此前可謂毫無頭緒。
“嬌小”的祖先
美國芝加哥菲爾德自然歷史博物館的助理館長馬克維奇博士領導了這次中美聯合考古工作。
馬克維奇博士說，這兩批暴龍屬化石之間存在著4000萬至5000萬年的空隙，現在雄關龍成了兩者之間一個“不錯的聯繫”。
馬克維奇博士與他的研究團隊在英國《皇家學會學報B卷》（生物學卷）上發表了研究結果。他們形容雄關龍是這兩個暴龍屬群體的“種系發生的、形態學的，和時間的聯繫”。
研究人員推算，一隻成年的雄關龍臀部高1.5米，體重270公斤。相比之下，一隻成年的雷克斯暴龍臀部高4米，體重超過5公噸。
同一期《皇家學會學報B卷》裡面還刊登了另一篇關於在甘肅發現恐龍化石的論文。
這篇論文所提及的似鳥龍下目（Ornithomimosauria）恐龍化石在甘肅酒泉地區與內蒙古交接的馬鬃山地區俞井子盆地發現，被命名為馬鬃山龍（Beishanlong grandis）。這個學名意味著北山龍體型十分巨大。
[url]http://news.bbc.co.uk/chinese/trad/hi/newsid_8010000/newsid_8011500/8011562.stm[/url] |
| fossilshk | 2009-4-22 03:50 PM |
|
| 真想看看中國的t_rex是什麼樣子......:L |
|
sciencenews.org 找到報導!
[size=6]
Remains of intermediate appear in a 40-million-year–long gap in tyrannosaur fossil record[/size][img]http://www.sciencenews.org/view/download/id/43051/name/EYE_TO_EYE_[/img]
The human-sized tyrannosaur Xiongguanlong baimoensis (gray) is an evolutionary intermediate between the smallest- and oldest-known tyrannosaurs (such as Dilong paradoxus, left) and the most recent behemoths such as Tyrannosaurus rex.
A newly described species of tyrannosaur is small enough to look humans in the eye. Fossils of the new tyrannosaur, Xiongguanlong baimoensis, help fill in details about the evolution of the fearsome meat-eating dinosaurs. Xiongguanlong lived in what is now western China between 110 million and 120 million years ago, says Peter Makovicky, a paleontologist at The Field Museum in Chicago. That era lies well within a 40-million-year–long gap in the tyrannosaur fossil record, he and his colleagues note online April 21 in Proceedings of the Royal Society B.
Remains of the creature suggest that Xiongguanlong weighed about 270 kilograms and stood about 2 meters tall at the hips. So, the meat-eating biped also fills the size gap that accompanies the time gap in the fossil record, falling between small ancestors such as Guanlong wucaii — a lithe, half-meter–high creature that lived about 160 million years ago — and multiton behemoths such as Tyrannosaurus rex, which stood about 4 meters tall at the hips and lived between 68 million and 65 million years ago.
The new remains “come from the business end of the animal, where many interesting aspects of tyrannosaur evolution occurred,” Makovicky says. For instance, the fossils suggest Xiongguanlong had a long narrow snout with flesh-nipping teeth at the front of its jaws, whereas later tyrannosaurs, including T. rex, had short-snouted skulls well-suited for crushing bones. |
| oviraptor | 2009-5-5 04:22 AM |
|
| 所謂霸王龍祖先就是同屬有血統關係的吧，像以住新彊的五彩冠龍吧 |
| freefall | 2009-5-15 07:44 PM |
|
| 以前倒是有異特龍可能是暴龍遠祖的說法(不過前肢指數就不同了 |
Powered by Discuz! Archiver 4.1.0
© 2001-2006 Comsenz Inc.
Processed in 0.00511 second(s), 2 queries |