Mathilde Boissier

Nils Ferrand

Emmanuel Krieger

Jean-Yves Y Courtonne

Peter Sturm

Playing with flows in transition territories

à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

These environmental and social challenges of the Anthropocene require us to imagine and implement alternatives to the current global economic organization. Accounting in biophysical flows (material, energy, land use, …) is one grid of analysis providing insights on the alternatives' sustainability (strong sustainability and ecological economics frameworks) [START_REF] Brunner | Handbook of material flow analysis: For environmental, resource, and waste engineers[END_REF][START_REF] Courtonne | Downscaling material flow analysis: The case of the cereal supply chain in France[END_REF][START_REF] Gabriel | A review of socio-economic metabolism representations and their links to action: Cases in agri-food studies[END_REF]. These tools are indeed relevant to highlight systemic effects (interdisciplinary understandings, spatial and temporal scales) on resources and important pressures to consider for the transformation of territories. If this biophysical flow vision may be very useful, it however remains for expert use only. However, one of the challenges of transition territories is to involve the populations in participatory processes in order to put their knowledge, wishes and specific capacities for action in synergy [START_REF] Abrami | Paper and pebbles simulations and modelling for the governance of socio-environmental systems: a review of 8 years of experimenting with the Wat-AGame toolkit[END_REF][START_REF] Becu | Les courants d'influence et la pratique de la simulation participative: contours, design et contributions aux changements sociétaux et organisationnels dans les territoires[END_REF][START_REF] Ferrand | WAT-A-GAME: sharing water and policies in your own basin[END_REF][START_REF] Voinov | Tools and methods in participatory modeling: Selecting the right tool for the job[END_REF]. Among the several participatory tools, serious games have long since proven their ability to sensitize to sustainability issues, facilitate learning and support changes. This paper presents an exploratory work to get insights on how playing with material and energy flows, fostering biophysical accounting and systemic vision learning to support stakeholders in territories' transitions. We first discuss general needs to support stakeholders in transition territories. We then detail how biophysical flows can be a tool to improve territories' sustainability. Section 3 and 4 are related to literature and some exploratory field experiments about flows involvement into games. We finally discuss the results in Section 5.

Supporting stakeholders in transition territories

Transition of territories (cities and / or rural area) requires multiple forms of engagement and adaptation from their stakeholders [START_REF] Moser | Communicating adaptation to climate change: the art and science of public engagement when climate change comes home[END_REF][START_REF] Reed | A theory of participation: what makes stakeholder and public engagement in environmental management work?[END_REF][START_REF] Soma | Stakeholder contributions through transitions towards urban sustainability[END_REF], under several biophysical and socio-institutional constraints. In this research, we focus on two groups: in the first one, policy makers, public engineers and public administrators, in the second one, citizens, private operators, and representatives of the civil society. The first have to cope with policy design, implementation and adaptation, while the second may consider engaging in behavioral change at household, daily activities or business level. They also try to use their democratic power upon representatives to take action. New dialogue processes may be required for both. Transiting toward alternative socio-technical organizations is their common challenge, if they endorse it.

It requires coordination and compliance with various constraints in terms of resource availability and use patterns, balanced satisfaction of stakeholders' expectations, and social or institutional norms. The related problematic framework shared with them can be formulated as: "how can we restructure our activities to cope now and later with the bounded or declining resources (natural or socio-technical), considering the diversity of our needs and uses, the prevalent power structure and the current social and institutional situation?"; and to feed the methodological design: "what are the induced stakeholders' needs in terms of learning, adapting social norms, social relationships and practices?" Our assumption and analysis are based on a synthesis of the past research around the Wat-A-Game modeling toolkit and more than 180 offspring games [START_REF] Abrami | Paper and pebbles simulations and modelling for the governance of socio-environmental systems: a review of 8 years of experimenting with the Wat-AGame toolkit[END_REF][START_REF] Ferrand | WAT-A-GAME: sharing water and policies in your own basin[END_REF], and of applied research on material flow analysis (MFA) [START_REF] Courtonne | Downscaling material flow analysis: The case of the cereal supply chain in France[END_REF][START_REF] Lenglet | Material flow analysis of the forest-wood supply chain: A consequential approach for log export policies in France[END_REF] with a focus on biophysical consistency built on expertise and data reconciliation.

In this paper, we target the following stakeholders' needs:

• Discovering and endorsing the systemic dependencies between multiple resources and activities in their living territories, • Considering and assessing possible technical and social alternatives, by testing and discussing mutually their social and ecological impacts, • Reflecting on social beliefs and preferences, and their consequences, • Engaging all stakeholders in an informed deliberation and decision process, leading to actual commitments and actions. When dealing with material flow for transition support, this requires to get the users to access and explore not only the material flow dynamic under impact of adaptation actions, but also to engage in social procedures opening toward new social norms and practices.

2

Biophysical flows as a tool to evaluate sustainability

Among the diverse tools developed to support transitions, we focus here on models centered on biophysical accounting. These tools aim at representing the society's functioning, analyzed through the biophysical (material and energy) flows controlled by humans, and highlight human-nature interactions and evolution over time [START_REF] Deutsch | Flow and impact analysis[END_REF][START_REF] Gabriel | A review of socio-economic metabolism representations and their links to action: Cases in agri-food studies[END_REF]. Among various environmental assessment methods (life cycle analysis, input-output analysis, footprints, ...), we focus here on material and energy flow analysis (MFA), tracking extraction, production, transformation, trade and waste flows [START_REF] Brunner | Handbook of material flow analysis: For environmental, resource, and waste engineers[END_REF][START_REF] Courtonne | Downscaling material flow analysis: The case of the cereal supply chain in France[END_REF][START_REF] Deutsch | Flow and impact analysis[END_REF]. MFAs provide insights for resource management and related pressures in territories and, providing adapted data gathering methods, can be worked on at company, local, regional and national scales [START_REF] Binder | From material flow analysis to material flow management Part I: social sciences modeling approaches coupled to MFA[END_REF][START_REF] Gabriel | A review of socio-economic metabolism representations and their links to action: Cases in agri-food studies[END_REF].

These tools ease systemic thinking. Because they are based on biophysical coherence (thermodynamics laws dealing on mass and energy), they track all flows thus reducing blind spots [START_REF] Deutsch | Flow and impact analysis[END_REF] : the relations between sectors are highlighted, as well as indirect links and thus indirect pressures. Some systemic effects are especially pointed out, such as competition for the use of resources (many use require the same resource), geographical pressure transfer (a territory externalizes pressures when local consumption involves external production inducing pressures in the producing territory), transfer between pressures (a production alternative shifts the pressure on the environment from one type to another), …. [START_REF] Boissier | Designing Serious Games to understand the challenges of the Anthropocene[END_REF]. Such clarification also reveals linkages between resources, organization and pressures. Moreover, these tools help to discuss the social system behind and the power and dependencies between stakeholders and the resource dynamic.

As they provide evidence for resource management, these tools are already used to support decisions. Companies and supply-chains use them to optimize material flows and waste streams in the production process (industrial ecology). Regions use them as a diagnosis tool to set up monitoring programs aimed at designing suitable strategies (e.g., regional bioeconomy strategies, regional biomass plan…). It is also an evaluation tool, used to assess the impact of scenarios of socio-economic development on resources and identify the resulting pressures [START_REF] Binder | From material flow analysis to material flow management Part I: social sciences modeling approaches coupled to MFA[END_REF][START_REF] Courtonne | Downscaling material flow analysis: The case of the cereal supply chain in France[END_REF]. A more extensive review list can be found in [START_REF] Gabriel | A review of socio-economic metabolism representations and their links to action: Cases in agri-food studies[END_REF].

Yet, these models are limited. Based on quantitative description, they require data and expertise, implying consequent gathering costs (data is not always available at the scale at which the decisions can be made, especially for local problems) [START_REF] Binder | From material flow analysis to material flow management Part I: social sciences modeling approaches coupled to MFA[END_REF][START_REF] Deutsch | Flow and impact analysis[END_REF], and methodology-dependency for knowledge collection. They are static (describing the current state of a system). There is no information collected and shown on derivatives and controls. Hence they cannot support dynamic simulation or show flows' evolution over time. Moreover, if the biophysical focus is relevant to detach from market considerations and focus on material and energy flows, it does not provide any decision framework that could help users to go beyond description and couple their social considerations to the biophysical constraints. Meanwhile social control is not represented either. To support decision coping with social constraints, these biophysical models should be coupled with social models (endogenous social integration) or be included explicitly in collective decision processes through participatory modeling [START_REF] Voinov | Tools and methods in participatory modeling: Selecting the right tool for the job[END_REF] or simulation like role-playing games (procedural social integration).

The latter approach, activates transdisciplinarity1 in a post-normal perspective, and involves non-scientific stakeholders who, by their social interaction and access to biophysical models, recouple both domains. In literature [START_REF] Gabriel | A review of socio-economic metabolism representations and their links to action: Cases in agri-food studies[END_REF], this is mostly done in a « trickle-down » (from researchers towards leaders), « transfer to translate » (scientists pay an effort to transfer knowledge to managers who translate it into action) or « users-push » (users -mainly leaders-ask researchers about the knowledge they require) ways. Yet, there still exists a gap regarding the involvement of a larger scope of stakeholders into the use of these models, especially in participatory processes with co-construction of the territory's transformations [START_REF] John | Toward sustainable urban metabolisms. From system understanding to system transformation[END_REF]. Such an involvement could be an opportunity to better understand the use and impact of MFA models into public decisions : do they really facilitate systemic thinking? Are they a good boundary object, fostering debate and deliberation (see [START_REF] Martin-Ortega | Are stakeholders ready to transform phosphorus use in food systems? A transdisciplinary study in a livestock intensive system[END_REF] for example)? What could be a good decision framework to be coupled with these tools ?

3

How are flows dealt with in games in literature?

Games have long since proven their ability to foster territorial transformations. Here we wish to assess the MFA use and impact on stakeholders and this might hint towards new ways to include it into participatory simulation games. In this section, we explore some games involving flows and biophysical coherence (we do not claim any exhaustivity in the game literature, but only a preliminary exploration that seemed relevant for further interrogations). Based on the readings and on Section 2, we then introduce a framework to analyze them.

To constitute this literature, the following key-words have been used together with "serious game"and then filtered depending on how we evaluated their interest for the study. These key-words correspond to sustainability fields involving MFA : " material flow analysis", "territorial metabolism", "territorial ecology", "urban metabolism", "territorial metabolism", "social metabolism" and "socio-economic metabolism". We have chosen to present here only the games that seemed to involve biophysical flows or had an intention to sensitize to a systemic analysis of the biophysical structure. To this first category, some nexus games and games related to circular economy or industrial symbiosis have been added to the study, as well as a few resource management games involving biophysical flows without focusing on them [START_REF] Ferrante | CAP'T'EN ValDech et CAP'T'EN Bois, deux jeux participatifs d'écologie territoriale pour la transition énergétique[END_REF][START_REF] Illatou | Impacts de l'orpaillage et de l'agriculture sur la qualité des eaux du Liptako nigérien : identification des hots spots des pollutions métalliques et organiques, transferts de connaissances entre recherche et terrain[END_REF][START_REF] Kain | Serious games in support of transformative multi-stakeholder sanitation planning for increased resource recovery: Specifications for game development[END_REF][START_REF] Kurt | Models and Tools for the Design, Assessment, and Evolution of Circular Supply Chains[END_REF][START_REF] Mochizuki | Simulation games as a catalyst for social learning: The case of the water-food-energy nexus game[END_REF][START_REF]PostfossilCities Homepage[END_REF][START_REF] Vinhas Goncalves | Multi-model Simulation for Serious Games in Sustainability Research[END_REF][START_REF] Schyns | Educational Nexus Game. MAGIC (H2020-GA 689669) Project Deliverable[END_REF][START_REF] Sušnik | Multi-stakeholder development of a serious game to explore the water-energy-food-land-climate nexus: The SIM4NEXUS approach[END_REF]. A large part of this research being also inspired by the Wat-A-Game toolkit [START_REF] Abrami | Paper and pebbles simulations and modelling for the governance of socio-environmental systems: a review of 8 years of experimenting with the Wat-AGame toolkit[END_REF][START_REF] Ferrand | WAT-A-GAME: sharing water and policies in your own basin[END_REF], which is a versatile modeling and game toolkit for water and other resource dynamic, we have included it for comparison sake. This literature is not exhaustive and is only aimed towards future game and experimentation perspectives.

We propose here a framework to analyze how MFA, their assets and their drawbacks are included into sustainability games. It is structured into two main parts.

Game analysis

In this part, we differentiate 3 categories:

Game objective. This category covers the intention of the authors when having this game played in terms of learning (L.) and expected participants (P.) Learning (L.). In the learning category, we have gathered the games authors' statements into 8 specific learning goals when addressing MFAs:

• interdependencies ("interdep."): (related to systemic learning) exploring interdependencies in sectors, along a supply chain, …

• time: (related to systemic learning) exploring time interdependencies (short and long term decisions consequences), • space: (related to systemic learning) exploring space interdependencies, • relational: discovering stakeholders' representations of reality, • sustainability: raising awareness of environmental disruptions, • stress: raising urgency and stake in the decisions,

• uncertainty: on the information about the present and the future,

• circularity: on optimizing a supply chain by introducing loops in flows. Within the games studied, the main learning objectives are to understand complexity (through experiencing the impact of interdependencies between sectors, space scales and time scales), sustainability issues and to make the participants realize how different representations of reality people can have and how this might affect collective decision. Game support.

• Online: numeric interface.

• Board: physical interface.

• Hybrid: physical and numeric interfaces. Game environment and roles. Description of the situation played (S.) and the stakeholders roles involved (R.). Material and energy resources are involved. As for the representations of these resources and flows, different strategies are used. First, some games hide the flows (and underlying models: black box effect) to the players and let them discover the system functioning through the impact their actions make on indicators. Some games let the biophysical resources be created and circulate between players without any focus on their transformations along the trip. As for resource transformation, they are involved in games pointing out a "supply chain" or "circularity" (CircusSChain [START_REF] Kurt | Models and Tools for the Design, Assessment, and Evolution of Circular Supply Chains[END_REF] focuses on making a supply chain circular, Sanitation planning game focuses on the circularity of wastes, CAP'T'EN ValDech and CAP'T'EN Bois [START_REF] Ferrante | CAP'T'EN ValDech et CAP'T'EN Bois, deux jeux participatifs d'écologie territoriale pour la transition énergétique[END_REF] involve biomass and wood supply chains).

Systemic learning.

In what way is this game aimed at pointing out systemic effects on resources that might otherwise remain blind spots: Interdependencies. ("I."): interdependencies in sectors (various activities/sectors related to each other), space scales, time scales (short and long terms). How these interdependencies are pointed out. ("H."):

• "relational": discussions to realize the interdependence, trade-offs and shared interests.

• "trade-off": between indicators, most solutions found to improve one indicator are actually trade-offs when considering all of them. • "game structure": the game structure (and associated flows) constraints the actions a player can take, and thus points out interdependencies. Each of these games (but CircusSChain [START_REF] Kurt | Models and Tools for the Design, Assessment, and Evolution of Circular Supply Chains[END_REF]) aims at proving how systemic thinking is important (consistent with the stated learning objectives), by putting the system under stress and forcing players to compromise. Yet, different strategies are used: some games directly use the flow structure, constraining players choice by the resource availability (token left) or pressure levels. A similar strategy is used through indicators: the constraint is not directly on the tokens availability but on sliders' choice to reach a chosen alternative in the feasible solution space left. Finally, and often used as the main strategy in nexus games, systemic learning is based upon the relationships between players: different roles involve different interests. Negotiations to improve one's interests lead to highlighting links between sectors and scales (links explicitly shown in the game or hidden in a computer code).

Decision framework.

What actions are available and how do the players' decisions intersect with the biophysical structure of the game. In most of the games, players were entitled to individual actions with consequences on the collectivity. These actions mainly depended on roles and could be

• controlling the biophysical flows (transport, production, transformation, trade, consumption and waste), • controlling the technology and infrastructures related to these flows (infrastructures and technology investments, infrastructures buildings), • controlling the social structure of these flows (resource allocation policies, resource management policies, life-style policies). Note that in each of the studied games, players are allowed to talk with each other and can thus collectively decide which individual actions each of them will take. In most of the games, socio-economic indicators have been added to force the integration of the biophysical structure in socio-environmental systems. Once again, the case of CircusSChain must be treated separately. The objective here is to optimize the supply chain by allowing its circularity, and is thus decorrelated from a real socio-environmental system. Most physical (board) games disclose and share all information, whereas digital games can keep secret some flows, processes or individual capitals. Information disclosure is anyway a key factor in the decision patterns.

Link to data. How real the data involved in the games are. Different choices can be made here, compromising between intelligibility (people can imagine the data) , accuracy (the data chosen allow a correct simulation of the phenomena at stake) and playability :

• using real data ("real"): in Table 1, this feature has been automatically chosen without mentioning otherwise in the articles for online games. This solution allows for a quantitative description of the biophysical system. In most of the games, indicators are added to help players to imagine the data and make their trade-offs. • using abstract discrete data: This solution is qualitative only and does not appear in the literature considered. The data is not related to reality. If the game might be simplified, the debriefing is then more complicated. • using discrete data transformed from real data ("disc"): in Table 1, this feature has been automatically chosen without mentioning otherwise in the articles for board games. This solution allows for the use of tokens. However, this requires hard work to remain accurate while reducing different data (types and orders of magnitude) to small integers. Note that in the games studied, we have found no purpose of pointing out data uncertainties.

4

Learning from field experimentations

In addition to literature analysis, we have conducted in this work three experiments to explore MFA and systemic based games as well as the use and impact of such models on participatory processes.

Creating a game focusing on the control of biophysical flows

Our first attempt consisted of the design of a game in which we copied a MFA structure to focus on systemic and biophysical coherence learning (spatial and sectors interdependencies) as well as sustainability issues, without introducing any money.

To this end, we chose to represent 4 territories sharing water and energy production, producing food (agriculture) and housing (wood and metals). Each territory has four slots to set up production or transformation industries. These slots take resources and transform them into other resources, GHG and pollution. The territories are related to each other through biophysical flows. To end with, each territory has work force units that must be fed and housed to be able to keep the facilities running.

We wanted to really focus on biophysical flows. Thus, we decided to represent every material and energy resource by tokens, being transformed during their journey along the different "supply chains". The systemic learning would then come through understanding how the chosen sectors were linked and how one territory could induce indirect pressures on another. The decision framework was mainly organizational: each player could decide what industry to set up in its territory and who he would trade with. Socio-economic indicators were introduced: the ability of each player to provide food and housing to its working force would determine a "social satisfaction". Finally, we fixed the numbers defining the efficiency of the different industries. We tried to choose them in coherence with reality but no real work has been done to transform continuous real data into small integers. This first attempt to play with flows happened to be far too complex. Indeed, if the initial situation allowed each player to fulfill its needs, changing this initialization required complex computations, similar to the reconciliation process 2 run to fulfill missing data for real MFA. Some flows became unknown and others remained determined: the players thus had to solve a discrete optimization problem to fill the gaps with relevance given the admissible space left. This barrier might be overcome by introducing stocks, a better designed playing time sequence. Following the literature, we could also think of introducing a calculation spreadsheet to help players.

Creating games focusing on pointing out biophysical systemic effects

In our second attempt, we chose to focus on systemic learning rather than biophysical flows representation. We chose two systemic effects and designed a game to experience each.

2 Data reconciliation is used in MFA to translate incomplete and inconsistent data to flows respecting e.g., mass conservation [START_REF] Cencic | Material flow analysis with software STAN[END_REF].

The first game (called "Chicken Game" [START_REF] Boissier | Designing Serious Games to understand the challenges of the Anthropocene[END_REF][START_REF] Vienot | Chicken game[END_REF]) aims at highlighting the geographic transfer of pressures. In this game, we follow the steps of making a roasted chicken, from the cultivation of soybeans in Brazil to the French supermarket. Each player represents a stage with its location and the pressures induced (land use, energy needs, water needs and greenhouse gas (GHG) emissions) and have information only about her/his step. One player plays the consumer. In the first phase of the game, the consumer walks up the production chain while the other players draw their way of representing the situation. In a second phase, the consumer goes back down the chain, collecting pieces materializing the different pressures and ends up in the supermarket with all the pressures induced on the chain. This game represents a supply chain. The resource that is transformed (grain towards chicken) is materialized by a magic card. The pressures are tokens. The flows are represented by the consumer's journey from the end of the supply chain to its beginning and way back. The players do not have many decision possibilities: they can only draw the situations and guess the effects of this supply chain. As for the data, small integers (because pressures represented by tokens) have been chosen with respect to Life Cycle Analysis studies. This game revealed that the process of transforming real data to small integers is a critical point. Indeed, the players couldn't project themselves in the game and discussed the realism of the settings instead of experiencing the pressure transfer effect. In MFA, several flow data are involved, sometimes with very different orders of magnitudes. Yet, "small flows" cannot always be neglected because of their relevance in the biophysical structure or their meaning in the socio-economical system. Thus, the game balancing process must be carefully chosen and strongly related to the test case considered.

In the second game (called "Cooperate or compete" [START_REF] Boissier | Designing Serious Games to understand the challenges of the Anthropocene[END_REF][START_REF] Vienot | Cooperate or compete[END_REF]) players must go through each round together by creating required products (3 different types, represented by the triangle, diamond and parallelogram). Each unit can be produced through 2 recipes, consuming different raw materials, obtained by exploiting a hexagonal territory. Some of them are renewable and others are not: the latter allow more efficient recipes, but they are depleting (obtained by a roll of the die, with increasing difficulty as the territory is exploited). Gradually deprived of these efficient recipes, players must fall back on renewable resources, leading to competition in their uses. This game does not represent flows but focuses on the transformation process. The resources are tokens, used to create products. To avoid the real data barrier, the resources are here chosen abstracts. However, this complicates the way back to reality (thus the learning), and a special attention must be paid to the debriefing phase.

Put energy flow analysis to the test on territorial consultation

To better understand how MFA can be related to stakeholders transforming territories, we also have animated three workshops with an energy flow analysis on the Pays Grand Briançonnais, composed of the Pays du Briançonnais, Écrins and Guillestrois-Queyras (France), on which operates a Pôle of Territorial and Rural Equilibrium (PETR). This territory will soon be involved in a participatory resource management process. Indeed, this mountain territory is the head of the Durance basin, with a strong hydroelectric potential and contains biodiversity reserves (Parc Naturel des Écrins, Regional Park of Queyras, Natura 2000 zones). The tourist economy is strong there, summer and winter (skiing). We have been asked by the president of the PETR to structure an "upstream" debate between the various stakeholders, and to reduce the various stakeholders, and to reduce the contentious blockages.

During three workshops (they were only preliminary experiments and further work is expected), we gave the participants (11 people in total) an energy flow analysis based on a diagnosis realized for the Plan Climat Air Énergie Territoire (PCAET). Already pointing out some interdependence, people asked about more accurate data. They especially required information on specific sectors, on different space scales (where do the flows exactly come from or go to, when imported to or exported from the territory, what is my contribution in this analysis), time scales (the diagram was for a year, but what about for a month, a wee, a season). They also asked for a socio-economic analysis to be coupled to this study. In particular, besides biophysical flows, knowing the actors controlling them and the levers of action to be associated. These first tests have therefore confirmed the ability of the MFAs to enable systemic analysis and the lack of a decision framework to really make the knowledge operable.

Analysis

Based on the literature and on these exploratory experiments, we infer the following insights about playing with biophysical flows in transition towards sustainability. We focus here on a board game, in which resources would be represented by tokens.

There is a critical relationship between the biophysical structure representation and the social decision framework, materialized in the players' actions:

• for the biophysical structure, players can control various resource flows intensities directly (through stocks control) or indirectly through the transformation processes (infrastructures, technology). This control can be individual and thus distributed between players, or collective, requiring players to negotiate and decide together. • for the social and institutional structure, players choose regulation flow rules, restricting or enabling the actions they can make on the biophysical structure.

Once again, this control can be individual (one player can control distribution policies related to one resource) but are mostly collective. There are also drivers on which the players cannot act. In sustainability contexts especially, the complex dynamics due to systemic effects can counterfact the players' intention.

This decision framework is related to the information flow in the game. Indeed, to avoid complicated discrete reconciliation, players must pre-decide and share options for resource flows. Actuation comes only after the use decisions were taken "downstream" by the "consumers". Negotiation can occur, as in real life. It requires a clear time sequence regulating an information cycle before action.

Toward a relevant game design, the users, for the goals categorized in [START_REF] Bots | Functional design of games to support natural resource management policy development[END_REF], would need to visualize stocks and flows, to decide and control them, under explicit social norms, to elicit and combine constraints related to various resources, to project future transformations, to relate this to various scales starting from their individual level. Therefore we propose the following alternative apparatus including the key useful features of MFA, but extended to support transition.

6

TransKey: a prototype model and game for transition support

After this analysis, we have designed a generic model to support new transition game design, adapted from the previous MFA games and goals. The target features are : representing multiple resource stocks and flows, their dynamics, stakeholders' constraints and control, exogeneous drivers, multi-scale representations, player friendliness, data fitting when required, connecting material and digital version. The resulting structure is described in Figure 5. -Processes carry, consume and produce various resources, for which a Process Function specifies the transformations and their conditions. -Taps control the outflows of stocks and the activation ratio of processes.

TransKey model and game

-The Network is the overall structure of interaction between components.

Colored arrows only show the topology of connections. The process WWW is a "pure transport flow", moving one resource from stock P2 to stock P1, at no extra cost with any other resource.

-Tapholders are social actors (persons or groups) animated by players or the game manager, who "own" some stocks, control the taps and discuss rules. The process functions pf should be of the form:

O pf (t) = pf(I pf (t-∆t),t,c pf (t))

where t is time, O pf (t) is the (discrete or continuous) vector of produced resources at discrete time t (round), I pf (t-∆t) the vector of the input resource at time (t-∆t) with ∆t a delay (equals 0, 1 or 2: a delay of 0 to 2 rounds), and c pf (t) the control over this process at time t. Autonomous processes without control exist. Social actuation and regulation: Stocks' and processes' taps are controlled by zero to many tapholders defined in a control matrix. For any "tap group", the "control rules" are specified, as mandatory rules (from the model settings) or as players' choice (dynamic : mean rule, vote, random, deliberation, etc).

Each tapholder or group has a payoff function depending on some stocks, singleor multi-valued (e.g. current state of one stock, set of values of 2 stocks, weighted sum of 3 stocks, growth, etc).

Tapholders' Activity & Dynamics :

1. Deciding or adjusting each "tap control rule", or keeping it as it is 2. Deciding and sharing stock' tap output "offers" by each stock tap group 3. By process tap, tapholders propose individually their control preference for tap, based on the upstream flow information. 4. The process tap group applies the "tap control rule" to set the process ratio, and the outputs. It computes the input resource actually consumed. 5. The new stocks are updated (subtracting and adding). 6. The tapholders evaluate their payoff. 7. Tap groups assess and express "demands" for incoming resource flows. 8. (option) Any tapholder can ask to enter any tap group, who accepts or not. 9. (option) Tapholders can activate new processes chosen in a set. A creation cost has to be "paid" from the tapholder' controlled stocks. The dynamic ends after some rounds or when a given payoff is reached.

Conclusion

If biophysical accounting and especially MFAs are undoubtedly useful to design transitions, they remain expert tools that cannot be manipulated easily by stakeholders transforming their territories. One way to better understand the use and impact of these models would be to make people play with them during serious games. The literature gives various insights on how to play with biophysical flows, and especially about how to represent them and which control players have on them. We supplemented this work by three field experiments which pointed out the importance of data, its accuracy and its transformation from real data to small integers. It once again pointed out the care to be taken in designing the decision framework. Indeed, to make sure players can build biophysically consistent scenarios, the playing sequence involving actions and information flows is crucial. From this study, a new game structure has been sketched and further work will include a full implemented design, putting them to the tests and analyzing people's reactions to better understand how MFAs could be used to support stakeholders in transition territories.

  . What resources, pressures are involved and how are flows and stocks represented. Biophysical resource representations. ("res. rep."): tokens, indicators, cards, …. Biophysical flows representations. ("flows")

Fig. 1 .

 1 Fig. 1. First attempt to play with MFAs.

Fig. 2 .

 2 Fig. 2. Chicken game, going back the chain.

Fig. 3 .

 3 Fig. 3. Cooperate or compete.

Fig. 4 .

 4 Fig. 4. Workshop session, presenting an energy flow analysis (December 2022).

  TransKey = {Resources, Stocks, Processes, Taps, Network, Tapholders, Control Matrix, Control Rules, Payoff, Activation Scheme} -Resources are any consumable and transferable resource, good or product. -Stocks are specified for each resource. Many stocks can exist for the same.

Figure 5 :

 5 Figure 5 : The TransKey model specification

Table 1 .

 1 Table captions should be placed above the tables ("abst": abstract., "coll.": collective, "disc.": discrete, "ind.": individual, "interdep.": interdependency, "res.": resource, "rep.": representation, "SE": socio-economic, "spatial.": spatialized, "stkh.": stakeholders)

	Game/projet	Goal	Game environment and	Biophysical flows representation Systemic	Decision framework	Link
	(and support)		roles				to data
	Wat-A-Game	L. interdep.	S. directed graph with	Res. rep: colored tokens for	I. Multi-functional	Ind. actuation of "action
	toolkit + 180	space. relational.	places and actions -any	representation of each resource	exchange and	cards" transforming res..
	offspring [1,	sustain.	discrete resource dynamic	Flows: movable card connectors	production system	Coll. decision on res.
	10] games	P. everyone	& sharing	on which the tokens circulate	H. Relational, trade-off	management and sharing.	Disc.
	(board,		R. any type			SE indicators (with and
	multiplayer)					without money).
	The Nexus	L. interdep.,	S. 2 countries sharing a	Res. rep: tokens (water, food,	I. Sectors (competition	Ind. (sectorial) actions
	Game [20]	relational.	river.	energy, pollution).	in the use of	(res. allocation,
	(board) (multiplayer)	P. policy makers, professionals,	R. Ministers (decide) journalist (observe).	Flows: only water flows between players. No focus on res.	resources), space, time.	infrastructures policies). SE indicators (with	Disc.
		students.		transformation.	H. Relational.	money).
	Sim4Nexus	L. interdep.,	S. Abst. spatial. territory.	Res. rep: indicators (food,	I. Sectors, time.	Ind. (sectorial) actions	Real.
	[27]	relational, time.	R. Managers of each	energy, water, climate, land use).	H. Relational,	(policies).
	(online)	P. everyone.	sector.	Flows: hidden in the computer	trade-off.	SE indicators (with
	(multiplayer)			code (system dynamics). No		money).
				focus on res. transformation.

We choose to consider transdisciplinarity as the collaboration between researchers from multiple disciplines with actors from non-scientific spheres[START_REF] Lawrence | Characteristics, potentials, and challenges of transdisciplinary research[END_REF].

Magic nexus [START_REF] Schyns | Educational Nexus Game. MAGIC (H2020-GA 689669) Project Deliverable[END_REF] (online) (


Donald Davesne
email: donald.davesne@gmail.com

Jorge Mondéjar-Fernández

Vachik Hairapetian
email: vachik@khuisf.ac.ir

Martin Rücklin
email: martin.rucklin@naturalis.nl

Jobst Wendt
email: jobst.wendt@uni-tuebingen.de

Gaël Clément
email: gclement@mnhn.fr

A new large tetrapodomorph sarcopterygian from the Late Devonian of Iran

Keywords: Sarcopterygii, Tetrapodomorpha, Middle East, Palaeozoic, Gondwana, CTscan, tooth microstructure, Tristichopteridae Kurzfassung Die Reste eines großen Sarcopterygiers wurden in der mittel-bis Diese Entdeckung stellt das erste Auftreten eines großen Tetrapodomorphen Sarcopterygii, Tetrapodomorpha, Mittlerer Osten, Paläozoikum, Gondwana, Computertomographie, Zahnmikrostruktur, Tristichopteridae

Remains of a large sarcopterygian were collected in the Middle-Late Devonian Zarand Formation of Southeastern Iran. These remains consist of incomplete jaw bones of uncertain identification, preserved in a dense and heterogeneous rock matrix. The use of CTscan microtomography and 3D visualization enabled to unravel their overall anatomy, as well as the microstructure of one tooth. This large tooth shows eusthenodont-type plicidentine, found only in Devonian tetrapodomorph sarcopterygians and more specifically suggesting affinities with the family Tristichopteridae. This discovery constitutes the first occurrence of a large tetrapodomorph in the Devonian of Iran and the Middle East.

Introduction

Our understanding of the vertebrate faunas that populated the Northern coasts of Gondwana at the end of the Devonian remains largely elusive. Few Upper Devonian vertebrate-bearing localities are known from regions considered as part of Northern Gondwana. Among these, sites from Morocco, Afghanistan, Iraq and Iran (e.g., [START_REF] Blieck | Vertébrés du Dévonien supérieur d'Afghanistan[END_REF][START_REF] Lelièvre | Silurian-Devonian vertebrate biostratigraphy of western Gondwana and related terranes (South America, Africa, Armorica-Bohemia, Middle East)[END_REF]; and references therein) have provided a diverse set of sarcopterygian (lobe-finned vertebrates) remains such as onychodontids, coelacanths and dipnomorphs, but tetrapodomorphs are poorly represented, except in the case of Moroccofrom which several cranial remains have been assigned to an "Eusthenopteron-like" tristichopterid [START_REF] Lehman | Sur la présence d'un Ostéolépiforme dans le Dévonien supérieur du Tafilalet[END_REF][START_REF] Lelièvre | L'Eusthénoptéridé (Osteichthyes, Sarcopterygii) du Famennien (Dévonien supérieur) du Tafilalt (Maroc) : nouvelle description[END_REF])and Iran [START_REF] Janvier | Les vertébrés dévoniens de l'Iran central II -Coelacanthiformes, Struniiformes, Osteolepiformes[END_REF].

In most palaeogeographical models of the Late Devonian [START_REF] Wendt | Devonian/Lower Carboniferous stratigraphy, facies patterns and palaeogeography of Iran. Part I. Southeastern Iran[END_REF][START_REF] Ruban | Review of Middle East Paleozoic plate tectonics[END_REF]), Central Iran is treated as a terrane located on the Northern margin of Gondwana (Fig. 1a). The Paleo-Tethys Ocean, evident in Iran by the presence of ophiolites [START_REF] Wendt | Devonian/Lower Carboniferous stratigraphy, facies patterns and palaeogeography of Iran. Part I. Southeastern Iran[END_REF], separated this terrane from Euramerica. The Devonian of Iran has yielded a diverse vertebrate fauna [START_REF] Golshani | Sur la paléogéographie et la paléobiologie du Dévonien dans la région de Kerman, en Iran[END_REF][START_REF] Golshani | Some aspects of the fish fauna in the late Devonian of Iran[END_REF][START_REF] Hairapetian | Devonian vertebrate biostratigraphy of central Iran[END_REF] comprising thelodonts, "acanthodians" [START_REF] Hairapetian | Early Frasnian acanthodians from central Iran[END_REF], chondrichthyans [START_REF] Long | Famennian microvertebrates from the Dalmeh area, central Iran[END_REF][START_REF] Hairapetian | Early Frasnian sharks from central Iran[END_REF], "placoderms" [START_REF] Schultze | Large Upper Devonian arthrodires from Iran[END_REF][START_REF] Janvier | Les vertébrés dévoniens de l'Iran central III : Antiarches[END_REF][START_REF] Lelièvre | Les vertébrés dévoniens de l'Iran central IV : Arthrodires et ptyctodontes[END_REF][START_REF] Lelièvre | Silurian-Devonian vertebrate biostratigraphy of western Gondwana and related terranes (South America, Africa, Armorica-Bohemia, Middle East)[END_REF], actinopterygians and sarcopterygians. The sarcopterygian fauna is composed of onychodontids, actinistians [START_REF] Janvier | Les vertébrés dévoniens de l'Iran central II -Coelacanthiformes, Struniiformes, Osteolepiformes[END_REF] and rhipidistians. Among rhipidistians, dipnomorphs are represented by dipnoan tooth plates and skull fragments and by a putative porolepiform cleithrum (Janvier and Martin, 1978).

Tetrapodomorphs are only represented by isolated scales and a fragment of a cosminecovered maxilla attributed to an undetermined "osteolepidid" [START_REF] Janvier | Les vertébrés dévoniens de l'Iran central II -Coelacanthiformes, Struniiformes, Osteolepiformes[END_REF].

Here we describe remains of a large tetrapodomorph from the Late Devonian of Southeastern Iran. Due to the heterogeneity of the surrounding siliciclastic matrix, a preparation using conventional, mechanical techniques was not suitable. It was thus decided to study the specimen by means of X-ray tomographic techniques (CT-scan) and 3Dvisualization. The scanning was performed at the AST-RX platform, MNHN, Paris (1965 transversal slices with an inter-slice spacing of 76,61 µm) and provided the basis for a digital reconstruction using the medical visualization software Mimics (version 14.0), which enabled to reconstruct structures that were hidden by the rocky matrix (Fig. 2b-d) and provided useful information on bone morphology and tooth microstructures (Fig. 3).

Institutional Abbreviations-MNHN, Muséum national d'Histoire naturelle, Paris, France

Systematic palaeontology

Osteichthyes Huxley, 1880Sarcopterygii Romer, 1955Tetrapodomorpha Ahlberg, 1991cf. Tristichopteridae Cope, 1889 (Figs. 2-3) Remarks-The presence of eusthenodont plicidentine in a Middle-Late Devonian sarcopterygian suggests an attribution of the specimen to the tetrapodomorph family Tristichopteridae (see below). However, despite the presence of an unusual combination of features, due to the incompleteness of the material we do not attempt to assign this specimen to any existing species or genus nor do we establish it as a new taxon.

Referred specimen-MNHN.F.URP 550, ensemble of jaw bones bearing teeth.

Locality and age-The specimen studied here, MNHN.F.URP 550, was collected during field work in 2001 by one of us (J.W.) in the Kerman region, Southeastern Iran (Fig. 1b). The specimen was discussed (although unnamed) by Wendt et al. (2002:138), first-by mistake from an earlier manuscript version-as an "acanthodian" and later corrected in the same publication as a sarcopterygian (Wendt et al., 2002:153, fig. 12). The specimen (Fig. 2a) comes from the sandstones of the Gask syncline, Zarand Formation (Fig. 1b,c), which is considered to be Devonian in age [START_REF] Wendt | Devonian/Lower Carboniferous stratigraphy, facies patterns and palaeogeography of Iran. Part I. Southeastern Iran[END_REF] due to the presence of Frasnian brachiopods in the upper part of the formation [START_REF] Huckriede | Zur Geologie des Gebietes zwischen Kerman und Sagand (Iran)[END_REF]. According to Wendt et al. (2002:153), the Zarand Formation is probably Givetian to Frasnian in age, spanning the Middle-Late Devonian boundary. The sedimentological model proposes that the Zarand Formation corresponds either to a shallow marine, possibly estuarine platform, or to a sebkha deposition, alternating with two episodes of marine regression that would explain the time gaps above and below the Zarand Formation [START_REF] Wendt | Devonian/Lower Carboniferous stratigraphy, facies patterns and palaeogeography of Iran. Part I. Southeastern Iran[END_REF].

Description

External morphology -Externally, MNHN.F.URP 550 appears as an elongate and narrow jaw bone association bearing teeth and measuring around 16 cm in length (Fig. 2a). The 3D reconstruction (Fig. 2b-d) shows that the specimen is divided in two parts separated by a transversal crack. This crack might match a transverse suture between two bones (hereafter called anterior and posterior bones). The overall labial curvature is sinusoidal. The labial surface lacks dermal ornamentation and, giving the rendering of the 3D model, appears smooth and unornamented. This indicates that it most probably corresponds to an internal surface of contact between bones rather than to an outer surface.

The bones appear as incompletely preserved. The anterior portion of the anterior bone is lacking and presents a longitudinal crack in its lingual margin, exposing the root of a large fang and its replacement fossa. The posterior portion of the posterior bone is also lacking and it appears that the bone has been fractured along its midline. In lingual view this fracture exposes a deep groove that could correspond to the lateral wall of a canal, possibly nervous, running throughout the bone. The anterior and posterior bones are separated by a depression that probably fitted the fangs of the opposite jaw when the mouth of the animal was shut.

The anterior bone bears a fang pair in which the posterior fang is entirely preserved; it is conical, with no remarkable curvature, and slightly compressed medially in its distal region resulting in a carinated profile (Fig. 2c). A replacement fossa, or pit, lies just anterior to it.

The posterior bone bears two fangs that are distally broken. They have roughly the same size and diameter, which suggests that they might have started growing at the same time. They are separated by a socket that presumably corresponds to a replacement fossa. This configuration can be defined as a fang triplet (two fangs and an intervening replacement fossa).

Laterally to the fang series the specimen bears a row of small teeth that spread along a vertical lamina, lining the fangs of both the anterior and posterior bones. There are six small teeth in the anterior bone and 13 in the posterior bone. The teeth series is incomplete in certain parts where teeth have been shed leaving one or two adjoining sockets with evidences of radial attachment bone at the base (Figs. 2c,3a). The close proximity of this row of teeth with the series of large fangs, as well as the lack of a visible suture in tomography images (Fig. 3a), suggest that both the fangs and the small teeth were part of the same bone(s) and thus the small teeth can be described as marginal teeth.

In front of the anterior fang pair, two large teeth are visible, although in a shedding process. These teeth are larger and stouter than the other marginal teeth. A small, older tooth is being evicted by a larger, younger tooth protruding underneath. The small tooth left an impression in the posterior margin of the larger one, which suggests that both teeth might belong to the same or to closely adjacent replacement pits. An incompletely preserved concavity in the anterior most margin of the anterior bone might correspond to a socket housing the next tooth of the marginal row.

Tooth microstructure -The internal microstructure of the complete anterior fang was revealed by the CT-scan data (Fig. 3). It shows a folded structure of the dentine (i.e., plicidentine).

The superficial orthodentine is folded with primary and secondary bends (Fig. 3a-b).

The folds are complex and subdivided in secondary folds towards the surface of the tooth (Fig. 3b). In the basal part of the tooth the bone of attachment extends between the dentine folds (Fig. 3c). In the centre there is a wide pulp cavity filled with matrix (in black), whereas in higher sections (Fig. 3a-b) the pulp cavity is filled by osteodentine, appearing less dense than the surrounding matrix. However, the osteodentine appears not to fill the pulp cavity completely, but is limited to its central part. This combination of structures matches the eusthenodont pattern, defined by [START_REF] Schultze | Die Faltenzähne der Rhipidistiiden Crossopterygier, der Tetrapoden und der Actinopterygier-Gattung Lepisosteus[END_REF][START_REF] Schultze | Folded teeth and the monophyletic origin of tetrapods[END_REF] in the fang of the genus Eusthenodon.

Discussion

The external and internal features displayed by MNHN.F.URP 550 and its virtual tomographic data are too partial and lack diagnostic characters that could undisputedly confirm whether the bones belong to an upper or a lower jaw. Given the state of the preservation and nature of the specimen, comprising two dermal jaw bones, two interpretations are possible (Fig. 2):

-the specimen corresponds to an upper jaw. The anterior bone then would probably correspond to a portion of the dermopalatine bone, while the posterior bone would be the ectopterygoid.

-the specimen corresponds to a lower jaw. In this case, the two bones would be better interpreted as two successive coronoids. Both interpretations will be taken into account for the forthcoming discussion.

External morphology -The anterior most portion of the specimen has proven difficult to interpret. There is no evidence of a choana, or of a lower jaw parasymphysial plate, but the anterior most portion of the bone complex is possibly lacking altogether. The enlarged anterior teeth, caught in a replacement process, are intriguing. They can correspond to a fang triplet on the dermopalatine/anterior coronoid. If the specimen is a lower jaw, a close resemblance can be signalled with the enlarged marginal teeth, anterior to the first coronoid, that are found in Gondwanan tetrapodomorphs such as Gogonasus (Long et al. 1997, fig. 38) and Mandageria [START_REF] Johanson | A new tristichopterid (Osteolepiformes: Sarcopterygii) from the Mandagery Sandstone (Late Devonian, Famennian) near Canowindra, NSW, Australia[END_REF].

The occurrence of a marginal dentition in the lingual jaw bones is a variable feature in tetrapodomorphs. Marginal teeth are always present on the dermopalatine/ectopterygoid complex, except on the anterior portion of the dermopalatine in some Gondwanan tristichopterids such as Mandageria [START_REF] Johanson | A new tristichopterid (Osteolepiformes: Sarcopterygii) from the Mandagery Sandstone (Late Devonian, Famennian) near Canowindra, NSW, Australia[END_REF]. On the coronoids, marginal teeth are unambiguously present in Eusthenopteron [START_REF] Jarvik | On the dermal bones, sensory canals and pit-lines of the skull in Eusthenopteron foordi Whiteaves, with some remarks on E. säve-söderberghi Jarvik[END_REF][START_REF] Zupiņš | A new tristichopterid (Pisces, Sarcopterygii) from the Devonian of Latvia[END_REF], Notorhizodon (G. C. [START_REF] Young | Crossopterygian fishes from the Devonian of Antarctica: systematics, relationships and biogeographic significance[END_REF], Langlieria [START_REF] Clément | A new tristichopterid (Sarcopterygii, Tetrapodomorpha) from the Upper Famennian Evieux Formation (Upper Devonian) of Belgium[END_REF], Heddleichthys [START_REF] Snitting | Heddleichthys -a new tristichopterid genus from the Dura Den Formation, Midland Valley, Scotland (Famennian, Late Devonian)[END_REF], Bruehnopteron [START_REF] Schultze | A tristichopterid sarcopterygian fish from the upper Middle Devonian of Nevada[END_REF] and in "elpistostegalians" [START_REF] Ahlberg | Lower jaws, lower tetrapods-a review based on the Devonian genus Acanthostega[END_REF][START_REF] Daeschler | A Devonian tetrapod-like fish and the evolution of the tetrapod body plan[END_REF]). On the other hand, they are absent in the tristichopterids Cabonnichthys [START_REF] Ahlberg | Second tristichopterid (Sarcopterygii, Osteolepiformes) from the Upper Devonian of Canowindra, New South Wales, Australia, and phylogeny of the Tristichopteridae[END_REF], Eusthenodon [START_REF] Johanson | Late Devonian sarcopterygian fishes from eastern Gondwana (Australia and Antarctica) and their importance in phylogeny and biogeography[END_REF] and Hyneria (J. M.-F. pers. obs.).

The depression that separates anterior and posterior bones is reminiscent of the intercoronoid fossae, typical in the lower jaw of tetrapodomorphs (e.g. [START_REF] Ahlberg | Second tristichopterid (Sarcopterygii, Osteolepiformes) from the Upper Devonian of Canowindra, New South Wales, Australia, and phylogeny of the Tristichopteridae[END_REF][START_REF] Parfitt | A large, anatomically primitive tristichopterid (Sarcopterygii: Tetrapodomorpha) from the Late Devonian (Frasnian) Alves Beds, Upper Old Red Sandstone, Moray, Scotland[END_REF]. In contrast, there is rarely a fossa separating the dermopalatine from the ectopterygoid.

The posterior bone bears only one fang triplet. There is classically only one fang pair or triplet on the middle coronoid and two on the posterior coronoid in tristichopterids [START_REF] Ahlberg | Osteolepiforms and the ancestry of tetrapods[END_REF]. There are also two fang pairs/triplets on the ectopterygoids in tristichopteridsexcept Tristichopterus and Spodichthys [START_REF] Snitting | A redescription of the anatomy of the Late Devonian Spodichthys buetleri Jarvik, 1985 (Sarcopterygii, Tetrapodomorpha) from East Greenland[END_REF]. The latter configuration might contrast with our specimen if it is interpreted as an upper jaw, but the ectopterygoid could also be posteriorly broken, explaining the absence of a second fang pair.

All fangs preserved in MNHN.F.URP 550 are straight, as clearly seen in the completely preserved anteriormost fang, which also shows two carinae or cutting edges. This condition approaches that of tristichopterids in which the fangs are usually straight and show carinated margins, at least in the dermopalatine-ectopterygoid complex and in the lower jaw [START_REF] Jarvik | On the dermal bones, sensory canals and pit-lines of the skull in Eusthenopteron foordi Whiteaves, with some remarks on E. säve-söderberghi Jarvik[END_REF].

Tooth microstructure -The CT-scan data revealed the presence of eusthenodont-type plicidentine in the large anterior fang of MNHN.F.URP 550 (Fig. 3). Plicidentine is present in different vertebrate taxa: extant lepisosteiforms and several other predatory actinopterygians [START_REF] Meunier | Presence of plicidentine in the labial teeth of Hoplias aimara (Erythrinidae; Ostariophysi; Teleostei)[END_REF], most fossil non-tetrapod sarcopterygians [START_REF] Schultze | Die Faltenzähne der Rhipidistiiden Crossopterygier, der Tetrapoden und der Actinopterygier-Gattung Lepisosteus[END_REF][START_REF] Schultze | Folded teeth and the monophyletic origin of tetrapods[END_REF], most of the first tetrapods (colloquially known as ''labyrinthodonts''), and several amniotes [START_REF] Maxwell | The structure and phylogenetic distribution of amniote plicidentine[END_REF]. Amongst Devonian vertebrates, plicidentine is found only in sarcopterygians, but not in onychodontids and actinistians [START_REF] Vorobyeva | Evolutionary modifications of the teeth structure in the Palaeozoic Crossopterygii[END_REF]. The polyplocodont plicidentine is the most general one amongst sarcopterygians as demonstrated by its presence in the early dipnomorphs Powichthys and Youngolepis [START_REF] Clément | Powichthys spitsbergensis sp. nov., a new member of the Dipnomorpha (Sarcopterygii, lobe-finned fishes) from the Lower Devonian of Spitsbergen, with remarks on basal dipnomorph anatomy[END_REF]. The dendrodont plicidentine of porolepiforms, the eusthenodont plicidentine and the labyrinthodont plicidentine of Panderichthys and tetrapods are certainly derived forms of polyplocodont plicidentine [START_REF] Schultze | Folded teeth and the monophyletic origin of tetrapods[END_REF].

Eusthenodont plicidentine is exclusively found in Devonian tetrapodomorph sarcopterygians such as Litoptychus [START_REF] Schultze | Die Faltenzähne der Rhipidistiiden Crossopterygier, der Tetrapoden und der Actinopterygier-Gattung Lepisosteus[END_REF]) andmost specificallyin the tristichopterids Eusthenodon [START_REF] Schultze | Die Faltenzähne der Rhipidistiiden Crossopterygier, der Tetrapoden und der Actinopterygier-Gattung Lepisosteus[END_REF], Platycephalichthys [START_REF] Vorobyeva | Evolutionary modifications of the teeth structure in the Palaeozoic Crossopterygii[END_REF], an isolated tooth from Belgium, possibly belonging to the genus Langlieria [START_REF] Clément | Large Tristichopteridae (Sarcopterygii, Tetrapodomorpha) from the Late Famennian Evieux Formation of Belgium[END_REF][START_REF] Clément | A new tristichopterid (Sarcopterygii, Tetrapodomorpha) from the Upper Famennian Evieux Formation (Upper Devonian) of Belgium[END_REF], and in the large Gondwanan tristichopterid Edenopteron (B. [START_REF] Young | A gigantic sarcopterygian (tetrapodomorph lobe-finned fish) from the Upper Devonian of Gondwana (Eden, New South Wales, Australia)[END_REF].

The reconstructed position of central Iran during the Middle-Late Devonian times is at the Northern margin of Gondwana [START_REF] Wendt | Devonian/Lower Carboniferous stratigraphy, facies patterns and palaeogeography of Iran. Part I. Southeastern Iran[END_REF][START_REF] Ruban | Review of Middle East Paleozoic plate tectonics[END_REF]. Given this palaeobiogeographic context, the only other coeval Gondwanan taxon showing a tooth microstructure similar to the one of our specimen is the tristichopterid Edenopteron from Australia (B. [START_REF] Young | A gigantic sarcopterygian (tetrapodomorph lobe-finned fish) from the Upper Devonian of Gondwana (Eden, New South Wales, Australia)[END_REF]).

Conclusions

The highly incomplete nature of the specimen MNHN.F.URP 550 renders a detailed anatomical description difficult, and a precise systematic attribution nearly impossible.

However, the overall morphology of the specimensuch as the presence of large fangs paralleled by smaller, marginal teethsuggests that it corresponds to the remains of a tetrapodomorph sarcopterygian. More specifically, the tooth microstructure matches the eusthenodont pattern, suggesting an affinity with the Devonian family Tristichopteridae for the specimen. This identification would not be surprising in the context of the reconstructed localisation of Iran at this time: right between Eastern (Australia) and Western Gondwana (Morocco) tristichopterid-bearing localities.

Although further fieldwork might retrieve more complete sarcopterygian remains from the region that would help to confirm the systematic position of MNHN.F.URP 550, this discovery adds up possible tristichopterids to the already diverse fauna of the Zarand Formation. This discovery is also significant because all other Gondwanan tristichopterids were found either in the eastern part of the supercontinent (G. C. [START_REF] Young | Relationships of tristichopterids (osteolepiform lobe-finned fishes) from the Middle-Late Devonian of East Gondwana[END_REF]B. Young et al. 2013), or in North Africa [START_REF] Lelièvre | L'Eusthénoptéridé (Osteichthyes, Sarcopterygii) du Famennien (Dévonien supérieur) du Tafilalt (Maroc) : nouvelle description[END_REF]. It showcases the need of further research on the Devonian faunas of the Middle East, with potentials implications on the comprehension of biogeography and biodiversity patterns at this time.

Figure captions

Fig. 1

 1 Fig. 1 Geographical and stratigraphical context. a Palaeogeographical map of the Late

Acknowledgements

The authors thank Arnaud Mazurier (Université de Poitiers) and the MNHN AST-RX platform 'Accès Scientifique à la Tomographie à Rayons X' (UMS 2700 'Outils et Méthodes de la Systématique Intégrative' CNRS-MNHN) for access to CTscanning facilities. Florent Goussard (MNHN) is warmly thanked for his support in 3D visualisation and software training. Philippe Loubry (CNRS-MNHN) took the photograph of Fig. 2a. Philippe Janvier (CNRS-MNHN), Per Ahlberg and Daniel Snitting (Uppsala University), Martin Brazeau (Imperial College, London), Zerina Johanson (Natural History Museum, London) and Jonathan Jeffery kindly provided helpful comments and discussions on jaw morphology. We warmly thank the editor Oliver Rauhut, as well as John Long and Hans-Peter Schultze for their thorough reviews of the manuscript. The specimen was discovered by J.W. during a fieldwork for the joint project initiated in 1995 by the Geological Survey of Iran (GSI), Tehran, and the Department of Geology of the University of Tübingen (Germany). We are indebted to the past and present directors of the GSI, Prof. Dr. M. Ahmadzadeh-Heravi and Dr. M. T. Korehie, and to Dr. M. Ghorashi (GSI Teheran) for their cooperation as well as the logistic and financial support of this project. Funding for the German counterparts was provided by the Deutsche Forschungsgemeinschaft (DFG, grant We 239/13-1-4). M. R. was supported by funds awarded to M. D. Brazeau from the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013) / ERC Grant Agreement number 311092. J. M.-F. was supported by 'La Caixa' Foundation (Spain). This work is a contribution to the TERRES project (n°ANR-2010-BLAN-607-0) of the French National Research Agency (ANR).