古植物學家發現了可能是傳說中的「第一朵花」

原文網址：www.sciencedaily.com/releases/2015/08/150817160613.htm

Paleobotanist identifies what could be the mythical 'first flower'

古植物學家發現了可能是傳說中的「第一朵花」

New analysis represents major change in the presumed nature of the planet's earliest angiosperms

新的分析展現了推測為地球上最早的被子植物在本質上發生的重大改變

Indiana University paleobotanist David Dilcher and colleagues in Europe have identified a 125 million- to 130 million-year-old freshwater plant as one of earliest flowering plants on Earth.

印第安納大學的古植物學家David Dilcher以及歐洲的科學家發現生活在1億2500萬至1億3000萬年前的一種淡水水生植物，可能是地球上最早的開花植物。

The finding, reported Aug. 17 in the Proceedings of the National Academy of Sciences, represents a major change in the presumed form of one of the planet's earliest flowers, known as angiosperms.

發表在8月17日的《美國國家科學院院刊》( Proceedings of the National Academy of Sciences)的發現顯示出推測為地球上最早的花朵(又稱為被子植物，angiosperm)，在型態上發生的重大變化。

"This discovery raises significant questions about the early evolutionary history of flowering plants, as well as the role of these plants in the evolution of other plant and animal life," said Dilcher, an emeritus professor in the IU Bloomington College of Arts and Sciences' Department of Geological Sciences.

「這項發現引發了更重要的問題：開花植物的早期演化史究竟為何，以及它們在其他動植物的演化中占據了何種地位。」Dilcher說，他是印第安納大學文理學院地質科學系的榮譽教授。

The aquatic plant, Montsechia vidalii, once grew abundantly in freshwater lakes in what are now mountainous regions in Spain. Fossils of the plant were first discovered more than 100 years ago in the limestone deposits of the Iberian Range in central Spain and in the Montsec Range of the Pyrenees, near the country's border with France.

雖然現為西班牙的山區，但在過去淡水湖遍佈時，名稱為Montsechia vidalii的水生植物曾一度在這些湖泊當中繁榮生長。早在一百多年前這種植物的化石就已經首度在鄰近法國邊界，西班牙中部的伊比利山脈以及庇里牛斯山蒙特塞克山脈中的石灰岩層中發現。

Also previously proposed as one of the earliest flowers is Archaefructus sinensis, an aquatic plant found in China.

在這之前另一種被認為可能是最早的花朵─中國古果(Archaefructus sinensis)，則是一種發現於中國的水生植物。

"A 'first flower' is technically a myth, like the 'first human,'" said Dilcher, an internationally recognized expert on angiosperm anatomy and morphology who has studied the rise and spread of flowering plants for decades. "But based on this new analysis, we know now that Montsechia is contemporaneous, if not more ancient, than Archaefructus."

「專業上來講，「第一朵花」其實是種迷思，就跟「第一位人類」一樣。」Dilcher說，他是享譽國際的被子植物解剖學及演化專家，鑽研開花植物的出現與散佈已長達數十年之久。「但根據最新的分析結果，我們現在確知Montsechia 就算不比中華古果還要古老，至少也會跟它生存在同一時代。」

He also asserted that the fossils used in the study were "poorly understood and even misinterpreted" during previous analyses.

他也主張他們研究的這些化石在之前的分析中，「根本沒有被仔細解析，甚至判釋錯誤」。

"The reinterpretation of these fossils provides a fascinating new perspective on a major mystery in plant biology," said Donald H. Les, a professor of ecology and evolutionary biology at the University of Connecticut, who is the author of a commentary on the discovery in the journal PNAS. "David's work is truly an important contribution to the continued quest to unravel the evolutionary and ecological events that accompanied the rise of flowering plants to global prominence."

「重新解析這些化石讓我們對這個植物學上的重大謎題有了引人注目的全新想法」。在PNAS期刊上對此論文撰寫評論的作者，康乃狄克大學生態學與演化生態學系的Donald H. Les教授說。「科學界一直致力於闡明開花植物崛起並成稱霸全球的過程中，曾伴隨哪些演化與生態事件。David的研究成果毫無疑問地對此議題有重大的實質貢獻。」

The conclusions are based upon careful analyses of more than 1,000 fossilized remains of Montsechia, whose stems and leaf structures were coaxed from stone by applying hydrochloric acid on a drop-by-drop basis. The plant's cuticles -- the protective film covering the leaves that reveals their shape -- were also carefully bleached using a mixture of nitric acid and potassium chlorate.

經由細心分析超過一千個用以下方法處理的樣品後，他們才做出這些結論。他們將鹽酸一滴一滴地慢慢滴在岩石上，以逐漸分離出嵌在其中的Montsechia化石的莖部以及葉片構造。葉片表面薄薄一層用來保護用的角質層，也利用硝酸與氯酸鉀的混合液來仔細脫除。

Examination of the specimens was conducted under a stereomicroscope, light microscope and scanning electron microscope.

這些經過處理後的樣品分別利用解剖顯微鏡、光學顯微鏡與掃描式電子顯微鏡來詳盡檢視。

The age of the plant at 125 million to 130 million years is based upon comparisons to other fossils in the same area, notably the freshwater algae charophytes, which places Montsechia in the Barremian age of the early Cretaceous period, making this flowering plant a contemporary of dinosaurs such as the brachiosaurus and iguanodon.

藉由比對同一地區出土的其它化石，其中又以輪藻(charophytes)這種淡水藻類最為重要，可以知道Montsechia的生存年代約在1億2500萬年至1億3000萬年前之間，白堊紀早期的巴姆雷期(Barremian age)。同時間與此開花植物共享棲地的恐龍包括了腕龍與禽龍。

The precise, painstaking analysis of fossilized structures remains crucial to paleobotany, in contrast to other biological fields, due to the current inability to know the molecular characters of ancient plants from millions of years ago, Dilcher said.

Dilcher說，由於目前的技術仍無法取得數百萬年以前的古代植物的分子特徵，因此相對於生物學的其他領域，分析化石結構這種需要高精確度且耗費心力的工作，對古植物學家而言仍然相對重要。

This careful examination was particularly important to Montsechia since most modern observers might not even recognize the fossil as a flowering plant.

對於Montsechia這種時下大部分的科學家甚至不認為它是開花植物的化石來說，細心的觀察更是至關重要。

"Montsechia possesses no obvious 'flower parts,' such as petals or nectar-producing structures for attracting insects, and lives out its entire life cycle under water," he said. "The fruit contains a single seed" -- the defining characteristic of an angiosperm -- "which is borne upside down."

「Montsechia 外觀上並沒有明顯與花相似的部分，像是用來吸引昆蟲的花瓣或是可以製造花蜜的構造，而且它們畢生都生活在水面以下。」他說。「它們的果實之中含有一顆種子，」─這是被子植物的決定性特徵─「以上下顛倒的方式生長。」

In terms of appearance, Dilcher said, Montsechia resembles its most modern descendent, identified in the study as Ceratophyllum. Also known as coontails or hornworts, Ceratophyllum is a dark green aquatic plant whose coarse, tufty leaves make it a popular decoration in modern aquariums and koi ponds.

Dilcher說就外觀上而言，Montsechia與金魚藻相當類似。這是他們在此研究中判斷出來，Montsechia生存於現代的後裔。金魚藻又稱為松藻，是一種深綠色的水生植物，其粗長且叢生的葉片使得它們成為現代水族箱與景觀池中的熱門造景用水草。

Next up, Dilcher and colleagues want to understand more about the species connecting Montsechia and Ceratophyllum, as well as delve deeper into when precisely other species of angiosperms branched off from their ancient forefathers.

接下來Dilcher與其同僚想要更了解連結Montsechia與金魚藻之間的物種為何，並且更深入探究其他被子植物與它們的老祖宗分家的準確時間點。

"There's still much to be discovered about how a few early species of seed-bearing plants eventually gave rise to the enormous, and beautiful, variety of flowers that now populate nearly every environment on Earth," he said.

「關於這些僅帶有種子的少數遠古物種，是如何演化出幾乎在現今地球上任何環境都能見到，為數眾多、繽紛且千變萬化的花兒，仍有許多事物有待我們去發現。」他說。

引用自：Indiana University. "Paleobotanist identifies what could be the mythical 'first flower': New analysis represents major change in the presumed nature of the planet's earliest angiosperms." ScienceDaily. ScienceDaily, 17 August 2015.