Credit: Andrey Zhuravlev, Lomonosov Moscow State University
Extreme fluctuations in atmospheric oxygen levels corresponded with evolutionary surges and extinctions in animal biodiversity during the Cambrian explosion, finds new study led by UCL and the University of Leeds.
The Cambrian explosion was a crucial period of rapid evolution in complex animals that began roughly 540 million years ago. The trigger for this fundamental phase in the early history of animal life is a subject of ongoing biological debate.
The study, published today in Nature Geoscience by scientists from the UK, China and Russia, gives strong support to the theory that oxygen content in the atmosphere was a major controlling factor in animal evolution.
The study is the first to show that during the Cambrian explosion there was significant correlation between surges in oxygen levels and bursts in animal evolution and biodiversity, as well as extinction events during periods of low oxygen.
Dr Tianchen He, study lead author and postdoctoral researcher at the University of Leeds, began this research while at UCL. He said: “The complex creatures that came about during the Cambrian explosion were the precursors to many of the modern animals we see today. But because there is no direct record of atmospheric oxygen during this time period it has been difficult to determine what factors might have kick started this crucial point in evolution.
“By analysing the carbon and sulphur isotopes found in ancient rocks, we are able to trace oxygen variations in Earth’s atmosphere and shallow oceans during the Cambrian Explosion. When compared to fossilised animals from the same time we can clearly see that evolutionary radiations follow a pattern of ‘boom and bust’ in tandem with the oxygen levels.
“This strongly suggests oxygen played a vital role in the emergence of early animal life.”
Study co-author Professor Graham Shields from UCL Earth Sciences, said: “This is the first study to show clearly that our earliest animal ancestors experienced a series of evolutionary radiations and bottlenecks caused by extreme changes in atmospheric oxygen levels.
“The result was a veritable explosion of new animal forms during more than 13 million years of the Cambrian Period. In that time, Earth went from being populated by simple, single-celled and immobile organisms to hosting the wonderful variety of intricate, energetic life forms we see today.”
The team analysed the carbon and sulphur isotopes from marine carbonate samples collected from sections along the Aldan and Lena rivers in Siberia. During the time of the Cambrian explosion this area would have been a shallow sea and the home for the majority of animal life on Earth.
The lower Cambrian strata in Siberia are composed of continuous limestone with rich fossil records and reliable age constraints, providing suitable samples for the geochemical analyses. The isotope signatures in the rocks relate to the global production of oxygen, allowing the team to determine oxygen levels present in the shallow ocean and atmosphere during the Cambrian Period.
Study co-author Dr Benjamin Mills, from the School of Earth and Environment at Leeds, said: “The Siberian Platform gives us a unique window into early marine ecosystems. This area contains over half of all currently known fossilised diversity from the Cambrian explosion.
“Combining our isotope measurements with a mathematical model lets us track the pulses of carbon and sulphur entering the sediments in this critical evolutionary cradle. Our model uses this information to estimate the global balance of oxygen production and destruction, giving us new insight into how oxygen shaped the life we have on the planet today.”
Study co-author Maoyan Zhu from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, said: “Understanding what triggered the Cambrian explosion requires multidisciplinary study. That’s why with Graham Shields we organized together such a multidisciplinary team funded by NERC and NSFC in past years. I am so excited about the results through this collaborative project.”
“On the other hand, it took a long time to get this result. We already got samples from Siberia in 2008. The sections in Siberia are difficult to access. It took time for us to organize the expedition and collect the samples there. Without support from Russian colleagues, we could not do the project.”
Study co-author Andrey Yu Zhuravlev from Lomonosov Moscow State University said: “This has been an incredibly successful and exciting joint study. The question of the Cambrian Explosion trigger has puzzled scientists for years. Now, the results give us convincing evidence to link the rapid appearance of animals as well as mass extinction during the early Cambrian with oxygen.”
###
Further information
The paper Possible links between extreme oxygen perturbations and the Cambrian radiation of animals is published in Nature Geoscience 06 May 2019. (DOI: 10.1038/s41561-019-0357-z)
Full list of authors: Tianchen He, Maoyan Zhu, Benjamin J. W. Mills, Peter M. Wynn, Andrey Yu. Zhuravlev, Rosalie Tostevin, Philip A. E. Pogge von Strandmann, Aihua Yang, Simon W. Poulton and Graham A. Shields
This work was facilitated and supported by a joint Sino-UK-Russia research collaboration.
UK institutes: UCL; University of Leeds; Lancaster University; University of Oxford
Chinese institutes: Nanjing Institute of Geology and Palaeontology, CAS; University of Chinese Academy of Sciences; Nanjing University
Russian institute: Lomonosov Moscow State University
For additional information please contact University of Leeds press officer Anna Harrison [email protected] or +44(0)113 343 4031
University of Leeds
The University of Leeds is one of the largest higher education institutions in the UK, with more than 38,000 students from more than 150 different countries, and a member of the Russell Group of research-intensive universities. The University plays a significant role in the Turing, Rosalind Franklin and Royce Institutes.
We are a top ten university for research and impact power in the UK, according to the 2014 Research Excellence Framework, and are in the top 100 of the QS World University Rankings 2019.
The University was awarded a Gold rating by the Government’s Teaching Excellence Framework in 2017, recognising its ‘consistently outstanding’ teaching and learning provision. Twenty-six of our academics have been awarded National Teaching Fellowships – more than any other institution in England, Northern Ireland and Wales – reflecting the excellence of our teaching. http://www.
About UCL (University College London)
UCL was founded in 1826. We were the first English university established after Oxford and Cambridge, the first to open up university education to those previously excluded from it, and the first to provide systematic teaching of law, architecture and medicine.
We are among the world’s top universities, as reflected by performance in a range of international rankings and tables, and are committed to changing the world for the better.
Our community of over 41,500 students from 150 countries and over 12,500 staff pursues academic excellence, breaks boundaries and makes a positive impact on real world problems.
http://www.
Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences
The Nanjing Institute of Geology and paleontology of the Chinese Academy of Sciences (NIGPAS) is the only academic institution specialized in invertebrate palaeontology and palaeobotany in China and is said to be one of the best research institutions of palaeontology and stratigraphy in the world.
The institute is engaged in basic and applied basic researches in palaeontology and stratigraphy, education and science communication. It is equipped with the advanced modern observational and analytical facilities for studies of fossil and sedimentary strata.
The institute has received many important awards, including a National Natural Science Award 1st Prize in 2003 for the work on Chengjiang fauna and the Cambrian explosion. In addition, seven out of 11 Global Boundary Stratotype Sections and Points (GSSPs) established in China have been defined by NIGPAS scientists.
NIGPAS is also actively engaged in international academic exchange, research collaboration and cooperation in graduate education. http://english.
Public Information Officer: Xiaozheng CHEN, E-mail: [email protected]
Oxford University
Oxford University has been placed number 1 in the Times Higher Education World University Rankings for the third year running, and at the heart of this success is our ground-breaking research and innovation.
Oxford is world-famous for research excellence and home to some of the most talented people from across the globe. Our work helps the lives of millions, solving real-world problems through a huge network of partnerships and collaborations. The breadth and interdisciplinary nature of our research sparks imaginative and inventive insights and solutions.
Through its research commercialisation arm, Oxford University Innovation, Oxford is the highest university patent filer in the UK and is ranked first in the UK for university spinouts, having created more than 170 new companies since 1988. Over a third of these companies have been created in the past three years.
Media Contact
Anna Harrison
[email protected]
Related Journal Article
http://dx.