THE MID-PALAEOZOIC BIOTIC CRISIS: SETTING THE TRAJECTORY OF TETRAPOD EVOLUTION

Lead Research Organisation: National Museums of Scotland
Department Name: Natural Sciences

Abstract

This project will shed light on a key stage in the evolution of life on Earth. The advent onto land of limbed vertebrates (tetrapods) was an event that shaped the future evolution of the planet, including the appearance of humans. The process began about 360 million years ago, during the late Palaeozoic, in the early part of the Carboniferous Period. Within the 20 million years that followed, limbed vertebrates evolved from their essentially aquatic and fish-like Devonian predecessors into fully terrestrial forms, radiating into a wide range of body forms that occupied diverse habitats and ecological niches. We know this because we have an adequate fossil record of the earliest limbed vertebrates from the Late Devonian, contrasting with the terrestrial forms that lived significantly later in the Early Carboniferous, about 340 million years ago. It is also clear that a mass extinction event occurred at the end of the Devonian, following which life on land and in fresh water habitats had to be re-established. Unfortunately, the formative 20 million years from the end of Devonian times has remained almost unrepresented for fossil tetrapods and their arthropod contemporaries. Thus, we know little about how tetrapods evolved adaptations for life on land, the environments in which they did so, and the timing or sequence of these events. The evolutionary relationships among these early tetrapods and how they relate to modern forms are also unclear and controversial as a result of this lack of fossil information. The entire fossil hiatus has been called 'Romer's Gap' after the American palaeontologist who first recognized it. Now, for the first time anywhere in the world, several fossil localities representing this period have been discovered in south-eastern Scotland. They have already provided a wealth of new fossils of tetrapods, fish, invertebrates and plants, and our team is the first to have the opportunity to study this material and the environmental, depositional, and climatic context in which this momentous episode took place. We have a number of major aims. The existing fossil material will form a baseline for this study, but the project will augment this by further excavating the richest of the sites so far found and subjecting it to a detailed archaeological-style analysis. We will collect from other recently recognized sites and explore for further sites with relevant potential. The fossil material will be described and analysed using a range of modern techniques to answer many questions related to the evolution of the animals and plants. Not only that, using stratigraphical, sedimentological, palynological, geochemical and isotopic data, we will establish the conditions of deposition that preserved the fossils, the environments in which the organisms lived and died, and the precise times at which they did so. We will drill a borehole that will core through the entire geological formation in which these fossils have been found. Using this, we will integrate data from our fossil sites using the signals provided by the sedimentary record to build a detailed time line showing in which horizons the fossils were found, the age of each occurrence and their sequential relationship. We will compare and correlate our data with that from contemporaneous deposits in Nova Scotia, the only other locality with information sufficiently rich to be meaningful. Our data will allow us to infer changes to the environment and the evolutionary trajectories of the animals and plants during the deposition of this formation, covering the 20 million years following the end-Devonian mass extinction. Comparison with similar data for the Late Devonian will allow us to chart the changes around the time of the mass extinction, to infer its causes and consequences, and obtain a detailed record of exactly how changes to the environment correlated with changes to the fauna and flora.

Planned Impact

The earliest Carboniferous (Tournaisian) interval (360-340 Ma) has long formed a 'bottleneck' in studies of the evolution of terrestrial ecosystems, and particularly the earliest evolution of terrestrial tetrapods, because of the almost complete lack of fossil evidence from this key time. We are now able to populate this hiatus in fossil data as a result of recent discoveries in Scotland, and to place these specimens in a palaeoecological and stratigraphic context.
Given the current paucity of data previously available for study of the faunas and floras from this time, and the profound changes to terrestrial ecosystems that took place then, we fully expect our results to be literally and metaphorically ground breaking. The material we will discover and describe will be of international significance, and enhance the reputation of the UK as a centre of excellence for Palaeozoic tetrapod fossils and their study. We anticipate publication in high profile journals including Science and Nature. Our palaeontological results will benefit interrelated disciplines from anatomists through molecular phylogeneticists to palaeoecologists. Biomechanics of locomotion, feeding, and breathing will gain from the new insight into the basal anatomical conditions at the onset of terrestriality. Studies of the evolutionary development of skeletal systems, and the timing of key innovations in tetrapod morphological adaptations will use our findings. Molecular phylogenies will benefit from new calibration points for the origins of the tetrapod and actinopterygian crown groups. The geological aspects of the proposal will benefit those modelling ancient climates in deep time, environmental and sedimentary systems, and their influence on and relationship to key evolutionary events. The refined stratigraphical, isotopic and palynological data that our studies provide will augment the, so far, relatively poorly known picture of this key period. Our comprehensive dataset from the earliest Carboniferous of Scotland will provide a future standard of comparison for contemporary deposits in other parts of the world.The industry-standard geophysical log data will be of interest to petrophysicists in academia and their industry partners, from including civil engineers, the construction industry and the hydrocarbon industries, who are studying the characterisation and prediction of physical properties in UK rock formations. As a team, we are particular well placed for high impact in the press and other media, with two members situated in nationally and internationally renowned museums, and with close links to others. Both institutions have professional in-house officers who deal with outreach on a continuing basis. Our experience talking to media representatives, the general public and other non-academics including people local to our sites, suggests that this project is of wide public interest and appeal.

Publications

10 25 50
 
Description Our understanding of the early colonization of land by vertebrates is now much better understood. We know for sure that the so-called "Romer's Gap" is not a real gap in the fossil record, but that between 360 and 345 million years ago there was a diversity of early tetrapod groups invading the land. Currently Scotland is the centre of this research, but we also know that North America is yielding some evidence to help piece together what was a pivotal step in the evolution of life on Earth. We have demonstrated beyond doubt that this was not a time of low atmospheric oxygen, as had been previously suggested, but a time of major change and the early radiation of tetrapod stook place under rapidly fluctuating and challenging environmental conditions.
Exploitation Route The concept of Romer's gap can now be put to one side, but importantly we have provided information on the ancient environments where the earliest tetrapods (vertebrate animals with four legs) lived. This will provide a much better framework for investigating this fundamental transition from water to land elsewhere in the world. Moreover the next phase in the radiation of tetrapods (particularly the amniotes) can be put into context.
Sectors Environment,Culture, Heritage, Museums and Collections

URL http://www.nms.ac.uk/national-museum-of-scotland/whats-on/fossil-hunters/
 
Description The findings of the research team have been featured in a 180 square metre temporary exhibit at National Museums Scotland that attracted over 50,000 visitors at national Museums Scotland. This exhibit later toured a number of venues in Scotland, targeting remoter areas that are not normally exposed to the direct results of scientific research. These included, Biggar and Clydesdale Museum, Montrose museum, Lews Castle in Stornoway, Nan Eilean on Benbecula and Dumfries and Galloway Museum. The exhibit was enhanced by a series of outreach programmes delivered by the research team
First Year Of Impact 2016
Sector Education,Culture, Heritage, Museums and Collections
Impact Types Cultural,Societal,Policy & public services

 
Description HLF funding for purchase of fossils associated with the project
Amount £161,700 (GBP)
Funding ID HG-12-03542 
Organisation Heritage Lottery Fund 
Sector Charity/Non Profit
Country United Kingdom
Start 01/2013 
End 11/2016
 
Description HLF funding for purchase of fossils associated with the project
Amount £161,700 (GBP)
Funding ID HG-12-03542 
Organisation Heritage Lottery Fund 
Sector Charity/Non Profit
Country United Kingdom
Start 04/2013 
End 03/2015
 
Description A public lecture to highlight the temporary Fossil Hunters exhibit at Montrose Museum 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact A public lecture, entitled: "A Fish out of water: the earliest Invasion of land by Animals with Backbones" at the opening of the temporary Fossil Hunters exhibit at Montrose Museum. One of the aims was to extend the reach of the research project to a wider audience away from the main centres of population. There were requests for additional programs in the future. In addition there were offers of support from local geologists.
Year(s) Of Engagement Activity 2016
 
Description BGS Open Day 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? Yes
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact The project was featured as part of the BGS Open Day in Edinburgh and included a display with some of the recent finds together with a poster explaining the context of the research to the wider public. In addition David Millward (BGS) Stig walsh (NMS) and Nicholas Fraser (NMS) were on hand to talk to visitors throughout the day.

We had offers of volunteer support for fieldwork and invitations for the wider group to give talks to other groups including local natural history societies
Year(s) Of Engagement Activity 2012,2013,2014
 
Description Edinburgh International Science Festival 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact The Edinburgh International Science Festival attracts a wide ranging audiences including, the general public, college students, other members of the science community and many visitors to the area (including international tourists). The presentation was an opportunity to place our research into context alongside a number of other scientific advances and it received positive feedback from other academics, foreign tourists and residents of the Borders where the primary field localities for our research are situated.
Year(s) Of Engagement Activity 2016
 
Description Lecture and Field Trip in Berwick and Northumberland. 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact A lecture and field trip excursion to local palaeontological sites associated with our project. This event was organized at the specific request from the Lindisfarne Peregrini Landscape project. Some members of the audience were professional geologists but many members of the audience were completely unfamiliar with our project. The event generated much keen interest and also highlighted some previous field work in the area that our group only had a little knowledge.
Year(s) Of Engagement Activity 2017
 
Description Lecture to the East Berwickshire U3A group 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Other audiences
Results and Impact This was lecture to an established University of the Third Age group. the attendees were all from the area where the majority of the field work for the research was carried out. It had the benefit of publicising the international importance of the audience's home to palaeontology. It has engendered in the local community a sense of belonging and pride together with a strong a desire to have future similar presentations. There were also numerous expressions of interest in volunteering for future fieldwork.
Year(s) Of Engagement Activity 2018
 
Description Presentation Berwick Educational Association 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Other audiences
Results and Impact A talk entitled: The Earliest Tetrapods for a local group of educators and retired professional. The aim was to raise awareness of the international significance of local fossil discoveries.
Year(s) Of Engagement Activity 2016
 
Description Public Lecture in Dumfries 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact As part of the Fossil Hunters touring exhibit that resulted from our research project, this was a public lecture in Dumfries and Galloway Museum. The audience largely interested lay people and included young adults, family groups and local politicians. This region has limited exposure to new scientific research and the lecture generated a good deal of discussion about the geology of Scotloand.
Year(s) Of Engagement Activity 2018
 
Description Public talk at Exhibit opening 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact A public lecture at the opening of the Fossil Hunters exhibit at Biggar and Upper Clydesdale Museum. The aim was to extend the reach of the research project to a wider audience in a rural part of Scotland. As a consequence there were request for additional such programs in the future and a request for regular updates on the progress of the research into early tetrapod life on land. Biggar and Upper Clydesdale Museum is one of a series of more remote communities in Scotland where we are taking the travelling exhibit.
Year(s) Of Engagement Activity 2016
 
Description Talk at Opening of Fossil Hunters Exhibit 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact The Fossil Hunters touring exhibit documenting the research findings of the team had an extended run in the Outer Hebrides (Lewis and then Benbecula). These are remote audiences that typically do not have access to this type of exhibit. The audience consisted of families, professionals, older adults and local dignitaries. Both the people attending and the museum expressed a desire to have other similar types of outreach programs in the future.
Year(s) Of Engagement Activity 2017
 
Description Temporary public exhibit and National Museums Scotland webpage 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact A special temporary exhibit entitled Evolutions Missing Chapter was developed and displayed at NMS from 6 March -29 April 2012. This featured some of the new material Willie's Hole material and was widely covered by the media in Scotland (newspaper, television and radio). This has since been developed into a webpage:





This is directly linked to the Consortium's web pages: www.tetrapods.org and www.tetrapodworld.com

Significant public interest was generated in the project including media interest
Year(s) Of Engagement Activity 2012
URL http://www.nms.ac.uk/about-us/services-and-expertise/science-engagement/the-tweed-project-evolution-...