CONICET | Buscador de Institutos y Recursos Humanos

A theoretical biomechanical model is proposed for the largest known 650 mm-long frond segment Neuropteris ovata var. simonii (Medullosales, Pennsylvanian, Sydney Coalfield, Canada). The study procedure includes, amongst others, a novel methodology for calculating density of fossil pinnules and rachides. This, in conjunction with the trait relationships and mathematical models that linked density and material/structural properties established for modern plant-leaf tissues, permits the estimation of tensile strength, tensile modulus of elasticity, flexural stiffness, and leaf mass per area. Results suggest that, theoretically, (a) the living frond invested a considerable amount of resources for the construction of metabolically expensive, hard, tough, and resistant pinnule and rachial tissues, which were ?made to last? and (b) were used as part of a combination of strategies that increased the plant´s biomechanical stability. This translated in resistance to damage during the application of external loads such as those exerted by strong winds or tropical storms. High leaf mass per area (dry-mass investment) of pinnules and rachial tissues points to a slow photosynthetic return that was sustained for long periods of time (long leaf lifespan). The latter possibly indicates a plant adaptation to wet, levee-top habitats, which were characterized by nutrient-deficient soils exposed to intensive solar irradiation. The 3D, chemistry-based model of the N. ovata specimen provided new insights into the hitherto poorly-known biomechanical and related traits of this iconic medullosalean plant that inhabited Pennsylvanian wetlands. Other implications of using our chemistry-based methodology include the estimation of (i) frond size and shape (plant reconstructions), (ii) plant ecophysiological adaptations to different wetland environments, and (iii) plant phylogenetic and ontogenetic adaptations.