原文網址：https://www.birmingham.ac.uk/news/latest/2021/09/dinosaurs-ascent-driven-by-volcanoes.aspx
一項新研究得出恐龍在2億3000多萬年前崛起的同時，大型火山爆發事件也造成了環境變遷。
2億3000萬年前強烈的火山活動造成了生態變化，為恐龍的統治奠下了基礎。圖片來源：University of Birmingham
在三疊紀晚期的「喀尼期洪積事件」(Carnian Pluvial Episode，CPE)可以看到全球氣溫與濕度增加，這對動植物的發展過程造成了重大影響，同時造就了現代的裸子植物。
研究人員分析中國北部濟源盆地的沉積物與植物化石紀錄，發現火山活動的高峰期和重大環境變遷的發生時間彼此吻合，像是2億3400萬年前到2億3200萬年前CPE的「超級季風」氣候。
包括伯明罕大學的專家在內的國際研究團隊，今日在《美國國家科學院院刊》(Proceedings
of the National Academy of Sciences)發表了他們的發現。結果顯示這段期間有四次獨立的火山活動事件，最有可能來自蘭格利亞大型火成岩區域的劇烈火山噴發，這些事件的痕跡至今仍保存在北美西部。
伯明罕大學地理、地球與環境科學院的古植物與古環境教授Jason
Hilton是共同作者之一，他評論：「在兩百萬年間，全世界的動物和植物經歷了某些重大變化，像是海洋生態系中特定生物的滅亡，以及陸上動植物族群的多樣化。這些事件都發生在一段雨量大增的特殊時期，稱為喀尼期洪積事件。」
「透過中國北方一座湖泊當中的詳細記錄，我們的研究得出這段時期事實上可以分成四次獨立事件，原因皆為強烈的火山活動達到另一次高峰。這會釋放非常多的二氧化碳到大氣當中，引發全球溫度與濕度增加。」
研究人員發現每次火山噴發的時候，全球碳循環都會遭到強烈的擾動，氣候也朝更加濕潤的方向大幅變動；於此同時，該湖泊也變得更深，氧氣與動物的數量也跟著減少。
在類似的時間範圍，從歐洲中部、格陵蘭東部、摩洛哥、北美、阿根廷……等地看到的地質事件，也指出雨量增加使得水域的面積大幅擴張。它們通常是匯集成湖泊或沼澤，而非河流與海洋。
「我們的結果顯示大型火山爆發事件可以達到好幾次不同的高峰，也證明了它們的能力非常強大，足以改變全球碳循環，擾動氣候與水文系統，並且驅動演化作用，」共同作者，同為伯明罕大學地理、地球與環境科學院的資深講師Sarah
Greene博士補充。
伯明罕大學的古生物學家Emma
Dunne博士並未參與這項研究，對此她評論：「這段相對長時間的火山活動與環境變遷勢必會對陸生動物造成可觀的影響。當時恐龍的多樣性才剛開始增加，如果沒有這次事件，牠們可能無法像我們在接下來的1億5000萬年看到的，成為生態系的主宰。」
Hilton教授也表示：「除了恐龍之外，這段地球歷史上的特殊時期對於現代裸子植物族群的崛起也至關重要；它也大幅影響了陸地生態系以及其他動植物的演化歷程，像是蕨類、鱷魚、烏龜、昆蟲和第一批哺乳類。」
Dinosaurs' ascent driven
by volcanoes powering climate change
The rise of
dinosaurs coincided with environmental changes driven by major volcanic
eruptions over 230 million years ago, a new study reveals.
The Late Triassic
Carnian Pluvial Episode (CPE) saw an increase in global temperature and
humidity - creating a major impact on the development of animal and plant life,
coinciding with the establishment of modern conifers.
Researchers analysed
sediment and fossil plant records from a lake in northern China’s Jiyuan Basin,
matching pulses of volcanic activity with significant environmental changes,
including the CPE’s ‘mega monsoon’ climate, some 234 million to 232 million
years ago.
The international
research team, including experts at the University of Birmingham, today
published their findings in Proceedings
of the National Academy of Sciences (PNAS)
– revealing four distinct episodes of volcanic activity during this time
period, with the most likely source being major volcanic eruptions from the
Wrangellia Large Igneous Province, the remnants of which are preserved in
western North America.
Co-author Jason Hilton,
Professor of Palaeobotany and Palaeoenvironments at the University of
Birmingham’s School of Geography, Earth and Environmental Sciences, commented:
“Within the space of two million years the world’s animal and plant life
underwent major changes including selective extinctions in the marine realm and
diversification of plant and animal groups on land. These events coincide with
a remarkable interval of intense rainfall known as the Carnian Pluvial Episode.
“Our research shows, in
a detailed record from a lake in North China, that this period can actually be
resolved into four distinct events, each one driven by discrete pulses of
powerful volcanic activity associated with enormous releases of carbon dioxide
into the atmosphere. These triggered an increase in global temperature and
humidity.”
The researchers found
that each phase of volcanic eruption coincided with large perturbation of the
global Carbon cycle, major climatic changes to more humid conditions, as well
the lake’s deepening with a corresponding decrease in oxygen and animal life.
Geological events from a
similar timeframe in Central Europe, East Greenland, Morocco, North America,
and Argentina, among other locations indicate that increased rainfall resulted
in widespread expansion of drainage basins converging into lakes or swamps,
rather than rivers or oceans.
“Our results show that
large volcanic eruptions can occur in multiple, discrete pulses -demonstrating
their powerful ability to alter the global carbon cycle, cause climate and
hydrological disruption and drive evolutionary processes,” added co-author Dr Sarah
Greene, Senior Lecturer also in the School of Geography, Earth and
Environmental Sciences at the University of Birmingham.
Dr Emma Dunne, a
Palaeobiologist also at the the University of Birmingham, who was not involved
in the study, commented: “This relatively long period of volcanic activity and
environmental change would have had considerable consequences for animals on
land. At this time, the dinosaurs had just begun to diversify, and it’s likely
that without this event, they would never have reached their ecological
dominance we see over the next 150 million years.”
Professor Hilton also
added “In addition to dinosaurs, this remarkable period in Earth history was
also important for the rise of modern conifer groups and had a major impact on
the evolution of terrestrial ecosystems and animal and plant life - including
ferns, crocodiles, turtles, insects and the first mammals.”
原始論文：Jing
Lu, Peixin Zhang, Jacopo Dal Corso, Minfang Yang, Paul B. Wignall, Sarah E.
Greene, Longyi Shao, Dan Lyu, and Jason Hilton. Volcanically driven lacustrine ecosystem changes during the Carnian
Pluvial Episode (Late Triassic). PNAS,
2021; DOI: 10.1073/pnas.2109895118
引用自：University
of Birmingham. “Dinosaurs' ascent driven by volcanoes powering climate change.”
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