By Matt McGrath, BBC News

媒體英語會帶大家一起學習 BBC 撰稿人在報道世界大事時常用到的單詞和短語。

Background: 在中國發現的一塊小型恐龍化石標本改變了多年來科學家們對鳥類起源研究的理論。一個半世紀以來，研究人員一直認為始祖鳥是最原始、最古老的鳥類，但最新發現的標本有可能改變這一看法。

Archaeopteryx has a hallowed place in science, long hailed as not just the first bird but as one of the clearest examples of evolution in action. But in recent years, doubts have arisen as older fossils with similar bird-like features such as feathers and wishbones were discovered.

Now Chinese researchers believe they have finally knocked Archaeopteryx off its perch. They've discovered another similar species named Xiaotingia which dates back 155 million years to the Jurassic era.

By carefully analysing and comparing the bony bumps and grooves of this new chicken sized fossil with Archaeopteryx, scientists now believe that both are in fact feathery dinosaurs and not birds at all.

Professor Lawrence Witmer from Ohio University, who has written a commentary on the finding, says the discovery will have huge implications for our understanding of the origins of birds. Such are the similarities between these transition species of reptiles and birds that scientists involved with this latest finding say that it certainly won't be the end of the argument. Further discoveries may change and even restore Archaeopteryx to its former glory.