Deuterostome decay - taphonomic testing of fossil anatomy and phylogenetic placement
Lead Research Organisation:
University of Leicester
Department Name: Geology
Abstract
Questions of how, when and why our earliest fish-like ancestors evolved are fundamental to understanding our place in evolution, but answers remain elusive because the fossil record of these events is hard to read. We will address this problem by investigating how the bodies of our primitive animal relatives change as they decay, shedding new light on controversial fossils that contain important clues to our own deep ancestry.
We, and all other animals with backbones, are classified as chordates, and sit together with some rather less familiar animals (sea squirts, acorn-worms, pterobranchs) on a major branch of the Tree of Life known as deuterostomes. This project will address a fundamental evolutionary question: what were our earliest chordate ancestors like, and how did they differ from their nearest deuterostome relatives? The principal difficulty in answering this question is understanding the early deuterostomes: after more than 500 million years of evolution, all the living groups of deuterostomes have modified their bodies in ways that make them quite different to one another. The evolutionary branches that sit between the living groups are all extinct, so the anatomically intermediate animals - which can lead us back down the evolutionary tree to those early ancestors - can exist only as fossils. Unfortunately these animals lacked hard skeletons. Their bodies were made entirely of soft tissues and generally rotted away when they died, leaving nothing for the fossil record. Against the odds, however, fossils have been found which seem to preserve the remains of ancient, long-extinct deuterostomes. The difficult job faced by palaeontologists is to interpret them correctly, and this is the subject of heated scientific debate. Our research project will take a new approach to analysing these controversial yet crucial fossil deuterostomes. We will study the way in which the characteristic soft-tissue features of different deuterostomes - such as muscles, tails, gill-slits and filter-feeding structures - rot and become fossilized, and determine whether we can reliably identify these characters in fossils. Fossils are essentially snapshots where decay has been frozen in time, and by decaying modern deuterostomes we will build up the kind of gory photofit - how important characters look at various stages of decay - that we need if we are to identify the characteristics of the fossils. So we will rot a variety of deuterostomes under controlled laboratory conditions. As they decompose we will carefully record the relative resistance to decay of the key features of their anatomy and how they change in appearance and position. We will also study how the soft-tissue characters of early deuterostomes actually became preserved, using a Scanning Electron Microscope to conduct detailed studies of the rare, exceptionally well-preserved fossil remains. Again, we will concentrate on important deuterostome characters, documenting their visual appearance, position and composition to determine the patterns and variability of preservation of each important feature. By analysing and comparing all these data we will be able to determine whether the fossil record can preserve recognizable early representatives of living deuterostome groups and their ancestors. Or did their remains rot too much, too fast, so that the characters that would allow them to be correctly identified were not fossilized? Nobody has ever investigated deuterostome fossils in this way (except our recent research, focussed on early vertebrates). The new project we propose builds on our expertise in this area and will allow us to develop novel methods and produce new data to address the important evolutionary questions at the heart of our proposal - the how, when and why of our own deep ancestry. Fossils have the potential to provide some answers to these big questions, but not until we learn how to correctly read the fossil record of rotted remains.
We, and all other animals with backbones, are classified as chordates, and sit together with some rather less familiar animals (sea squirts, acorn-worms, pterobranchs) on a major branch of the Tree of Life known as deuterostomes. This project will address a fundamental evolutionary question: what were our earliest chordate ancestors like, and how did they differ from their nearest deuterostome relatives? The principal difficulty in answering this question is understanding the early deuterostomes: after more than 500 million years of evolution, all the living groups of deuterostomes have modified their bodies in ways that make them quite different to one another. The evolutionary branches that sit between the living groups are all extinct, so the anatomically intermediate animals - which can lead us back down the evolutionary tree to those early ancestors - can exist only as fossils. Unfortunately these animals lacked hard skeletons. Their bodies were made entirely of soft tissues and generally rotted away when they died, leaving nothing for the fossil record. Against the odds, however, fossils have been found which seem to preserve the remains of ancient, long-extinct deuterostomes. The difficult job faced by palaeontologists is to interpret them correctly, and this is the subject of heated scientific debate. Our research project will take a new approach to analysing these controversial yet crucial fossil deuterostomes. We will study the way in which the characteristic soft-tissue features of different deuterostomes - such as muscles, tails, gill-slits and filter-feeding structures - rot and become fossilized, and determine whether we can reliably identify these characters in fossils. Fossils are essentially snapshots where decay has been frozen in time, and by decaying modern deuterostomes we will build up the kind of gory photofit - how important characters look at various stages of decay - that we need if we are to identify the characteristics of the fossils. So we will rot a variety of deuterostomes under controlled laboratory conditions. As they decompose we will carefully record the relative resistance to decay of the key features of their anatomy and how they change in appearance and position. We will also study how the soft-tissue characters of early deuterostomes actually became preserved, using a Scanning Electron Microscope to conduct detailed studies of the rare, exceptionally well-preserved fossil remains. Again, we will concentrate on important deuterostome characters, documenting their visual appearance, position and composition to determine the patterns and variability of preservation of each important feature. By analysing and comparing all these data we will be able to determine whether the fossil record can preserve recognizable early representatives of living deuterostome groups and their ancestors. Or did their remains rot too much, too fast, so that the characters that would allow them to be correctly identified were not fossilized? Nobody has ever investigated deuterostome fossils in this way (except our recent research, focussed on early vertebrates). The new project we propose builds on our expertise in this area and will allow us to develop novel methods and produce new data to address the important evolutionary questions at the heart of our proposal - the how, when and why of our own deep ancestry. Fossils have the potential to provide some answers to these big questions, but not until we learn how to correctly read the fossil record of rotted remains.
Planned Impact
The questions at the core of our project bear directly on our understanding of our own deep ancestry and relationships with other animals. What were our earliest chordate ancestors like, and how did they differ from their nearest deuterostome relatives? Fundamental curiosity about these big questions extends well beyond academic beneficiaries into the wider public, and research combining this with somewhat gory decay experiments and exceptionally well-preserved fossils provides an excellent vehicle for engaging general audiences, including non-scientists and children, with fundamental and exciting yet accessible NERC funded science. We will ensure that we engage with these wider audiences through: Distribution of press releases through Eurekalert and AlphaGalileo, leading to dissemination of information via mass media and blogs. The investigators have an excellent track record of effective promotion and presentation of their research using these methods. The PDRA will be sent on the NERC public engagement course in order to ensure full participation in this process. We will also have details of our project written in non-technical language on a project specific website. This will include time-lapse movies of rotting animals (our first crude attempts at this, with lampreys, are available on our 'rotten fish & fossils' website: www.le.ac.uk/gl/rottenfossils). We will incorporate the results of our new experiments into our public engagement exhibition 'Rotten Fish and Fossils' and participate in major public engagement events (e.g. Big Bang & Cheltenham Festival).
The combination of big questions about our origins combined with a simple experimental approach to their investigation - very much along 'horrible science' lines - provides excellent material for introducing experimental science into primary school class rooms. This is important: a recent review of the UK science curriculum concluded that a strong negative or positive primary science experience carries through for the next six or seven years, and that 56% of children thought there should be more practical science in the primary school classroom (Cerini et al. 2003). Our discussions with primary school teachers provide anecdotal support for this. The new Draft National Curriculum for science Key Stages 1 and 2 (2012) includes specific requirements such as observing closely using simple equipment, recognising and controlling variables, classifying animals based on specific characteristics, describing and comparing common animals to prehistoric life and extinct animals, fossil evidence for evolution, fossil evidence for the characteristics of living things that inhabited the Earth many years ago. Our discussions with teachers and educational professionals indicate that there will be a demand for training and teacher resources in this area. Consequently we plan to run workshops and develop simple classroom experiments (modified from our controlled laboratory experiments) to rot things under different conditions to explore the process of fossilization and anatomical change. We will modify our methods so that cheap and readily available equipment and materials can be used to produce repeatable results, and allow for experimental conditions to be varied. We will test various sealed decay vessels (coffee jars and the like), various sediment types (sand, clays, soils) and various remains to be decayed (sardines, prawns, slugs, snails, sausages). Instructions and information will be made freely available online. We will work with professionals to ensure engagement with beneficiaries, and in developing CPD. We will run workshops (in-house and in-school) following-up on the 'horrible' experiments by showing how this helps us to understand fossilization, with hands-on access to high-quality replicas of exceptionally preserved non-biomineralized fossils and reconstructions of the animals as they would have been in life, together with real fossil material.
The combination of big questions about our origins combined with a simple experimental approach to their investigation - very much along 'horrible science' lines - provides excellent material for introducing experimental science into primary school class rooms. This is important: a recent review of the UK science curriculum concluded that a strong negative or positive primary science experience carries through for the next six or seven years, and that 56% of children thought there should be more practical science in the primary school classroom (Cerini et al. 2003). Our discussions with primary school teachers provide anecdotal support for this. The new Draft National Curriculum for science Key Stages 1 and 2 (2012) includes specific requirements such as observing closely using simple equipment, recognising and controlling variables, classifying animals based on specific characteristics, describing and comparing common animals to prehistoric life and extinct animals, fossil evidence for evolution, fossil evidence for the characteristics of living things that inhabited the Earth many years ago. Our discussions with teachers and educational professionals indicate that there will be a demand for training and teacher resources in this area. Consequently we plan to run workshops and develop simple classroom experiments (modified from our controlled laboratory experiments) to rot things under different conditions to explore the process of fossilization and anatomical change. We will modify our methods so that cheap and readily available equipment and materials can be used to produce repeatable results, and allow for experimental conditions to be varied. We will test various sealed decay vessels (coffee jars and the like), various sediment types (sand, clays, soils) and various remains to be decayed (sardines, prawns, slugs, snails, sausages). Instructions and information will be made freely available online. We will work with professionals to ensure engagement with beneficiaries, and in developing CPD. We will run workshops (in-house and in-school) following-up on the 'horrible' experiments by showing how this helps us to understand fossilization, with hands-on access to high-quality replicas of exceptionally preserved non-biomineralized fossils and reconstructions of the animals as they would have been in life, together with real fossil material.
Publications
Murdock DJ
(2016)
The impact of taphonomic data on phylogenetic resolution: Helenodora inopinata (Carboniferous, Mazon Creek Lagerstätte) and the onychophoran stem lineage.
in BMC evolutionary biology
Murdock, DEJ
(2014)
BEYOND THE BUCKET: TESTING THE EFFECT OF EXPERIMENTAL DESIGN ON RATE AND SEQUENCE OF DECAY
in Abstracts of the 4th INTERNATIONAL PALAEONTOLOGICAL CONGRESS
Purnell M
(2016)
Experimental taphonomy and the anatomy and diversity of the earliest fossil vertebrates (Chengjiang Biota, Cambrian, China)
in Geophysical Research Abstracts
Purnell M
(2018)
Experimental analysis of soft-tissue fossilization: opening the black box
in Palaeontology
Description | Research is ongoing, but we have already determined how various factors involved in the process of decay and fossilization of organisms do, or do not, affect what disappears and what is preserved. We have also developed new methods for analysis of whether factors, such as sediment type, organisms size, and organism type, affect the rate and timing of onset of decay. |
Exploitation Route | mainly scientific impact, but we are developing classroom based experiments for primary schools based on our research |
Sectors | Education,Environment |
Description | public engagement event - University Week 2014 |
First Year Of Impact | 2014 |
Sector | Education,Culture, Heritage, Museums and Collections |
Impact Types | Cultural,Societal |
Description | NERC Research Experience Placement |
Amount | £2,800 (GBP) |
Organisation | Natural Environment Research Council |
Sector | Public |
Country | United Kingdom |
Start | 07/2017 |
End | 09/2017 |
Description | Palaeontological Association Grants in Aid |
Amount | £4,620 (GBP) |
Organisation | Palaeontological Association |
Sector | Charity/Non Profit |
Country | United Kingdom |
Start | 04/2016 |
End | 06/2016 |
Description | Palaeontological Association Grants in Aid |
Amount | £5,850 (GBP) |
Funding ID | PA-GA201606 |
Organisation | Palaeontological Association |
Sector | Charity/Non Profit |
Country | United Kingdom |
Start | 04/2017 |
End | 06/2017 |
Description | Palaeontological Association Research Grant |
Amount | £5,844 (GBP) |
Organisation | Palaeontological Association |
Sector | Charity/Non Profit |
Country | United Kingdom |
Start | 07/2012 |
End | 12/2012 |
Description | Palaeontological Association undergraduate research experience bursary |
Amount | £1,600 (GBP) |
Organisation | Palaeontological Association |
Sector | Charity/Non Profit |
Country | United Kingdom |
Start | 07/2015 |
End | 09/2015 |
Description | Pigmented and Organically preserved soft-bodied fossils - using taphonomic mode to interpret anatomy |
Amount | £75,000 (GBP) |
Funding ID | 1802213 |
Organisation | Natural Environment Research Council |
Sector | Public |
Country | United Kingdom |
Start | 10/2016 |
End | 03/2020 |
Title | systematic analysis of the relationship between decay in extant models/experiments and data from exceptionally well-preserved fossils |
Description | We establish a quantitative approach that unites data from decay experiments of extant taxa with preservation mode of fossils, allowing evaluation of both information loss and information retention, and their interaction, in non-biomineralized fossils. We demonstrate that frequency of occurrence of characters in fossil taxa is significantly correlated with sequences of character decay observed in extant comparator organisms, and that decay prone and decay resistant characters have distinct preservation modes; the former are mineralized and the latter are organically preserved. The methods and principles applied here to non-biomineralized vertebrates are applicable to other exceptionally-preserved fossils and allow for identification of systematic biases in fossil specimen completeness, character retention and the mode of their preservation. Furthermore, our analyses validates experimental decay in supporting the interpretation of anatomy in non-biomineralized fossils. |
Type Of Material | Improvements to research infrastructure |
Year Produced | 2021 |
Provided To Others? | Yes |
Impact | method underpins a number of research outputs not yet published |
Title | quantitative modelling and comparison of anatomical decay sequences in experiments and character composition of fossils |
Description | We unite data from decay experiments of extant taxa with preservation mode from fossil specimens, allowing evaluation of both information loss and information retention, and their interaction, in non-biomineralized fossils. The methods and principles are generally applicable to exceptionally-preserved fossils and allow for identification of systematic biases in fossil specimen completeness, character retention and the mode of their preservation. Furthermore, our analyses validates experimental decay in supporting the interpretation of anatomy in non-biomineralized fossils. |
Type Of Material | Data analysis technique |
Year Produced | 2021 |
Provided To Others? | Yes |
Impact | n/a |
Description | Yunnan Key Laboratory for Palaeobiology |
Organisation | Yunnan Key Laboratory for Palaeobiology |
Country | China |
Sector | Academic/University |
PI Contribution | collaborative research programme, involving joint research and co-authored outputs, and likely exchange of research students |
Collaborator Contribution | collaborative research programme, involving joint research and co-authored outputs, and likely exchange of research students |
Impact | Cong et al 2014 |
Start Year | 2014 |
Description | Rotten fish and Fossils activity |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | Yes |
Geographic Reach | National |
Primary Audience | Schools |
Results and Impact | lots of engagement and dialogue - stimulated interaction not simply delivery of information increased interest in science as a career; increased interest in curiosity driven research |
Year(s) Of Engagement Activity | 2012,2013,2014 |
Description | Zombie fossils press release |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | Press release on 'zombie fossils' linked to paper on our research published in Palaeontology generated significant attention, including interview of team member on BBC Radio 4 'Today' Programme, and some articles. |
Year(s) Of Engagement Activity | 2018 |
Description | engagement at open days |
Form Of Engagement Activity | Participation in an open day or visit at my research institution |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Other audiences |
Results and Impact | public engagement activity presented to prospective geology students and their families as part of open day activities |
Year(s) Of Engagement Activity | 2015,2016 |