Impact of global disturbances on the evolution of life in the polar regions during the early Cenozoic (PALEOPOLAR)

Lead Research Organisation: NERC British Antarctic Survey
Department Name: Science Programmes

Abstract

The greenhouse world of the Late Cretaceous to mid-Paleogene (~100 - 40 million years ago) is of particular interest to earth scientists because there is good geological evidence to show that at this time tropical/subtropical conditions extended into Antarctica in the south and into the Arctic in the north. At this time the south polar ice cap was either much smaller or absent. Many modern groups of plants and animals have their evolutionary roots in this greenhouse world and it is possible that their expansion related directly to this prolonged period of global warmth. This greenhouse world was punctuated by a mass extinction event at 65Ma at the Cretaceous - Paleogene boundary (K-Pg). In addition, this warm world was interrupted by a series of abrupt extreme warming events, or hyperthermals, probably caused by the sudden release of massive amounts of CO2 into the atmosphere and oceans. The K-Pg mass extinction event probably had a much longer-lasting effect on global ecosystems than the more transient hyperthermals but we will test this idea by investigating the geological record from the polar regions, the regions on Earth most sensitive to environmental and climate change. Much of the geological record for this time interval for the polar regions comes from deep sea drill sites but the best onshore exposure is found on Seymour Island, Antarctica. We have recently investigated this locality in detail and now have a high resolution geological record from the end of the Cretaceous period, across the K-Pg boundary and into the mid-Paleogene period. Analysis of large collections of sediments and plant and invertebrate fossils will provide us with new information about climates on land and temperatures in shallow seas around Antarctica at that time. The fossils also allow us to reconstruct the composition of faunas and floras that lived in the polar regions and to determine how their diversity changed over time. We will produce a new palaeotemperature curve for the latest Cretaceous - mid-Paleogene interval in Antarctica, and will assess whether the hyperthermal events occurred so far south. By matching fossil diversity with the climate record we will assess the time taken for plants and animals to recover from the K-Pg mass extinction and investigate whether times of high biodiversity were linked to episodes of warming. For example, do sub-tropical plant fossils and an unusual marine fossil assemblage represent poleward incursions of warmth-loving biotas during a global warming event 55 million years ago, only to go extinct when cooler conditions returned? Some studies indicate that the K-Pg mass extinction reset the global evolutionary clock forever, with new species subsequently appearing at a much higher rate in the tropics than at the poles. We will test this important theory by adding our new Antarctic fossil data to a global database for the latest Cretaceous to the mid-Paleogene. Was the radiation of species through this interval really slower at the poles, and if so, why did the change in rates occur immediately after the K-Pg boundary? How does our record of palaeoclimate and biodiversity from Antarctica compare to that from the Arctic and from low latitude sites - were high latitude communities particularly sensitive to climate change and environmental disturbance, even in a greenhouse world? How did forests at the poles affect the climate system? Does our fossil record match the evolutionary history derived from modern marine faunas by molecular studies? By using a range of palaeoenvironmental indicators and analytical techniques (isotope geochemistry, sedimentary facies analysis, palaeobotany, palaeobiology, climate modelling) we will reconstruct the greenhouse world of the past and assess the impact of dramatic global events on the evolution of life, particularly in the polar regions.

Publications

10 25 50
 
Description Our PALEOPOLAR project was designed to investigate the impact of global events on the evolution of life on Earth in the Early Cenozoic era (i.e. between approximately 66 and 34 million years ago). These events included the recovery of the global system from the mass extinction event at the Cretaceous - Paleogene (K/Pg) boundary, and a series of global warming events from the latest Paleocene to Middle Eocene that saw the Earth's temperature rise abruptly over geologically rapid timescales. A particular question that we framed at the outset of the study was whether these events may have had a direct effect on the formation of some of the largest-scale patterns of life on Earth seen at the present day. These included, in particular, latitudinal gradients in taxonomic diversity that document, for many groups of organisms, far more species in the tropics than at the poles. These comprise one of the fundamental patterns of life on Earth.
Although our fieldwork has been based exclusively in the Antarctic, we have also incorporated various Arctic datasets into our analyses wherever possible. Seymour Island at the north-eastern tip of the Antarctic Peninsula was extensively studied by us and we have used the exceptionally well exposed sequence of sedimentary rocks there to establish a new chronology of Early Cenozoic events in Antarctica. Much of this has been painstaking work, involving the matching of both macro- and microfossil records through a 1000m+ thickness of strata. However, once this was accomplished we could then track the evolution of climates on a fine timescale, and to our surprise various lines of evidence pointed to predominantly cool climates through the last 2 m.y. of the Cretaceous period (i.e. just before the mass extinction event). Indeed, blooms of certain species of dinoflagellate microfossils suggest that there may even have been the formation of winter sea ice at certain levels (Bowman et al. 2013a, b). Cool conditions continued into the earliest Cenozoic (Paleocene) epoch where we used some of the latest geochemical proxies obtained from sediment samples to obtain palaeotemperature values in the region of 10° - 12°C (Kemp et al. 2014). However, these values rise sharply in the latest Paleocene, and this trend is continued into overlying Eocene strata. Here, a combination of geochemical proxies and various fossils indicate that warm temperate climates prevailed. These detailed studies provide an invaluable global reference point for palaeoclimate modellers.
Our studies have shown that the extinction of ammonites and other marine taxa at the K/Pg in Antarctica was every bit as intense as in lower latitude regions; the high-latitudes were not necessarily buffered against global change. This in turn strongly suggests that the extinction event was both global and severe; features that match well with an asteroid impact scenario. A quantitative analysis of neogastropods indicates a significant increase in rates of speciation between the K/Pg and Middle Eocene. We count this as further evidence to indicate that the mass extinction event reset the evolutionary stage on a global scale. In particular, modern marine organisms are much more common after the mass extinction event than before it.
The 700m-thick Eocene succession exposed on Seymour Island is one of the most complete and fossiliferous anywhere in the Southern Hemisphere. Detailed examination of both its stratigraphy and fossil content indicates that the mid- to upper levels are Middle Eocene in age. Molluscan fossil assemblages from these levels are particularly rich and provide further tantalising evidence that this epoch comprises a global diversity maximum for the Early Cenozoic. However, we know that the global temperature maximum for this interval occurred in the Early Eocene, and this mis-match provides important evidence that there is not necessarily a direct correlation between temperature and biodiversity.
The rise of the large neogastropod clade between the K/Pg boundary (66 Ma) and the Middle Eocene (~45 Ma) in Antarctica is matched by much steeper rises in tropical localities such as the Paris Basin and Gulf Coast, USA. In addition it is clear that those groups of neogastropods which rise to prominence in Antarctica are all trophic generalists that eat a wide variety of prey items. This in turn is thought to be a strategy to cope with the extreme seasonality of food supply in polar environments. Even though the Early Cenozoic was a period of global greenhouse warmth, the poles would still have had extremely seasonal climates. It is seasonality at the poles, and the much shorter period of primary production there, as much as temperature, that structures much of the biology we see both at the present day and in the past.
Work in progress suggests that not only was the Middle Eocene a global biodiversity maximum for the Early Cenozoic, but it was also a time when latitudinal diversity gradients steepened markedly. However, rather than reflecting the slow diffusion of species from low to high latitudes (the so-called "Out of the Tropics" hypothesis), the latitudinal diversity gradient may represent a series of primary radiations that simply progress at higher rates in the tropics than the poles. Such a process was undoubtedly enhanced later in the Cenozoic by extinctions and range retractions coincident with the onset of global cooling.
Study of Early Cenozoic polar marine biotas is providing crucial new evidence as to how modern biodiversity patterns formed, and thus in turn how stable they may be to sustained global change.
Exploitation Route The initial benefits will be mainly within the academic communities of macroecology and biodiversity. Biogeographic patterns on the grandest of spatial and temporal scales are structured by something more than latitudinal or longitudinal changes in temperature. In the sea the seasonality of primary production, which lies at the heart of the food chain, also varies strongly with latitude and plays a key role in defining the structure of polar marine communities. Climate change can affect the process of marine primary production in a number of different ways and this in turn can strongly influence the primary food source in polar marine ecosystems. It may be seasonality rather than low temperature per se that is the fundamental control on the stability of these ecosystems. This has very important implications for those monitoring biodiversity levels and commercial fish stocks in the polar regions.
However, as the full implications of our work are assessed by the wider community, including conservationists, environmental planners, and various governmental organisations, we anticipate that there will be some important implications for the global change community. Our work is helping to define more clearly the nature of large-scale biodiversity patterns, and how they may have formed through time. Given the rate at which so many natural communities are currently being destroyed, we believe that our work will provide vital background for all those working to preserve biodiversity from local to global scales.
We are taking our palaeotemperature studies forward through the award of a BAS Collaboration Voucher to Vanessa Bowman, Alistair Crame and Stuart Robinson. Using labs in Earth Sciences at both Oxford and Cambridge we aim to double-check temperature values in Antarctica through the Late Cretaceous and Early Cenozoic using the rapidly developing fields of clumped isotopes from fossil shells and geochemical proxies from sediment samples. There is still much to do to refine the precise timing of the global switch from greenhouse to icehouse states.
We are also hoping to develop our work on the link between the K/Pg mass extinction event and the rise of modern biodiversity patterns through a new NERC - National Science Foundation of China collaboration to study biosphere resilience through deep time. Using this and other new collaborations we aim to test the link between climate change and biodiversity datasets throughout the Late Mesozoic and Early Cenozoic. Temperature may correlate strongly with biodiversity at the present day but has it always done so in the past?
Sectors Agriculture, Food and Drink,Education,Environment,Government, Democracy and Justice,Culture, Heritage, Museums and Collections

URL http://www.lifeandplanet.net
 
Description On the very simplest of levels our work has helped to convey to government officials and ministers, various industrial and commercial companies, the general public, and school children, the sheer complexity of life in the polar regions. Many people have simply no idea that in the past the poles were green and forests covered the highest latitudes. We commissioned two pieces of "Palaeoart" to demonstrate what life may have looked like on land in the Antarctic 60 million years ago, and in the sea at the end of the Cretaceous period (66 m.y. ago). Simply by displaying these at various events we have been able to demonstrate how completely the Earth has changed over geological timescales. Similarly, we have exhibited polar rocks and fossils regularly at the Lyme Regis Fossil Festival (2012-2016), with the attendance latterly exceeding 14,000 people. In 2016 we enlisted the help of an enthusiastic amateur, and a fossil shop in Poland, to reconstruct one of the largest ammonites ever found in Antarctica. This is an uncoiled form, or heteromorph, which we collected in over 30 different pieces in Antarctica. It has now been re-assembled to the highest display standards and will be exhibited in BAS for staff and visitors alike to enjoy. In 2012 we exhibited at the Science Uncovered exhibition in the Natural History Museum, London where over 8,500 members of the public attended, along with a delegation from the EU. We have talked to three different primary schools in the region and taken with us not only rocks and fossils for the students to examine but also polar camping equipment and clothing. At all these events the interest levels have been extremely high and we know from various forms of feedback that the idea of exotic life forms at the poles was fascinating but challenging for many people. There is no simpler or more dramatic way of demonstrating the impact of global change. In January 2014 we presented our work to Mark Simmons MP, an FCO Minister, when he visited BAS and followed this up with an article on "Polar predictions" for the journal International Innovation (Crame et al. 2014). This journal specialises in disseminating science, research and technology to both government departments and industry; it is also widely distributed through the EU community. We were also co-organisers of the NERC-sponsored "Co-evolution of Life and the Planet" meeting held in the Geological Society of London, 5-6 November 2014. Although the talks and posters here were very largely academic, we made an attempt at the end to synthesise the key events in Earth history going back more than a billion years. These range from the rise of oxygen in the Precambrian, through various mass extinctions, to the descent into the modern icehouse. The talks were all videoed and are now available on the web. The Geological Society is also a powerful medium for disseminating information to a wide variety of stakeholders via the web, newsletters and various publications. Various aspects of our work have been publicised on the Life and the Planet website: www.lifeandplanet.net There is also a Twitter feed: @lifeandplanet1, and a Facebook page: "Coevolution of Life and the Planet". In addition, a palaeoclimate modelling project at the University of Bristol has made an innovative attempt to attract a more general audience to this field: http://www.bris.ac.uk/news/2013/10013.html This allows modellers to set up global climate models in their own time to simulate the climate of Tolkien's Middle Earth! But there is a serious message about using modelling to predict global change into the future. The "past as a key to the future" is a powerful message to convey to all our stakeholders. Whilst we have found that it is very easy to do this with younger audiences, we have also learnt the importance of having a short, succinct statement of our research findings for busy professionals. This is especially so for politicians and senior administrators who are constantly bombarded with information; an "elevator speech" is essential to make any sort of impact with them. As part of NERC's 50th Anniversary celebrations two members of the PALEOPOLAR team took part in a Jurassic Fossilblitz at Lyme Regis in August 2015. This involved a team of experts helping members of the public of all ages to identify fossils exposed on the beach at Lyme Regis during low tide. We helped them to identify different fossils, and then count numbers in small quadrats. All the kids got stickers and an I/d chart to take home, and it was a hugely enjoyable event. Plans are now well advanced for a permanent display of fossils resulting from the PALEOPOLAR project to be established at BAS, Cambridge.
First Year Of Impact 2011
Sector Education,Environment,Culture, Heritage, Museums and Collections
Impact Types Cultural,Societal

 
Description BAS Collaboration Voucher
Amount £5,000 (GBP)
Organisation British Antarctic Survey 
Sector Academic/University
Country United Kingdom
Start 01/2016 
End 01/2017
 
Title Neogastropod species dataset 
Description Crame, J. Alistair "Neogastropod species lists from the Early Cenozoic of Seymour Island Antarctica, US Gulf Coast and Paris Basin" (2018) Polar Data Centre, Natural Environment Research Council, UK doi:10.5285/e3a0d52f-b974-414b-9e13-41b171ed659c 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
Impact These files comprise lists of neogastropod species from the Early Cenozoic of Seymour Island, Antarctica and tropical counterparts in both the US Gulf Coast and Paris Basin. They comprise a key part of the raw data analysed in the paper Crame et al. (2018). For each of these three localities species are listed in taxonomic order, following conventional taxonomic notation. Faunas are listed for the Paleocene, Early Eocene and Middle Eocene time intervals for the two tropical localities, but only for the Paleocene and Middle Eocene of Antarctica. The accurate location of all the localities is given in a series of published papers. The Seymour Island samples were collected across three field seasons; 1999, 2006 and 2010. The US Gulf Coast and Paris Basin data were constructed from existing literature. Funding was provided by the NERC grants NE/I005803/1 and NE/C506399/1. 
URL https://ramadda.data.bas.ac.uk/repository/entry/show/?entryid=e3a0d52f-b974-414b-9e13-41b171ed659c
 
Description Lecture to University of the 3rd Age (U3A) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Other audiences
Results and Impact U3A provides a set of structured learning courses for retired people from all sorts of backgrounds. This was part of a set of lectures on the polar regions and was set at a level suitable for both professionals and enthusiastic amateurs. The title was "The Cretaceous - Paleogene mass extinction event in Antarctica, and its aftermath". This was one of the most dramatic extinctions in Earth history and set in place the rise of modern mammals, including humans. The extinction event was no less severe in Antarctica than in any other part of the world.
Year(s) Of Engagement Activity 2018
 
Description Participation in the University of Cambridge Summer Programmes 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Undergraduate students
Results and Impact Lecture and demonstration entitled "The geological and evolutionary past of the world's coldest continent". The University of Cambridge Summer Programmes are designed to give undergraduate students from around the world the chance to learn about a whole series of topics to increase their general knowledge and awareness of current topical issues. This lecture formed part of a week-long series on the biology of Antarctica, with special reference to climate change.
Year(s) Of Engagement Activity 2018
 
Description The Cretaceous - Paleogene mass extinction event in Antarctica, and its aftermath 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Study participants or study members
Results and Impact Lecture and demonstration given to the Oxford branch of the Open University Geological Society. The audience comprised mostly enthusiastic amateur geologists of all ages; they were amateurs with an intelligent interest in all types of geology. The talk described not only current geological research but also how we live and work in the polar regions. The talk was subsequently written up for the OUGS Oxford Branch Newsletter.
Year(s) Of Engagement Activity 2016