A possibilistic framework for modelling morphological evolutionary pathways: the example of catarrhine dental diversity

This study introduces an innovative application of qualitative and possibilistic modeling within the Ecological Discrete Event Network (EDEN) framework, to explore morphological evolution. EDEN is used to explore how qualitative rules describing trait dependencies shape the range of possible evolutionary outcomes. As a case study, we encode four qualitative dental traits representative of catarrhine molar morphology into two discrete-event models, to explore patterns of morphological evolution and responses to environmental changes. Rather than reconstructing phylogenies or estimating probabilities, EDEN exhaustively explores all trajectories compatible with these qualitative rules, allowing us to identify different evolutionary pathways. The approach reveals both known and previously unrecognized morphological states, clarifies the conditions required for transitions between them, and highlights the influence of traits such as cusp shape, enamel thickness, and loph or wrinkle development. More broadly, this work demonstrates how possibilistic modeling provides a new and complementary framework for investigating morphological evolution by exploring the complete range of trajectories compatible with explicit biological hypotheses.