Selective recovery of terrestrial arthropod feeding guilds in a Middle Triassic flora from Mendoza, Argentina

Abstract

This study surveys a discrete macrofossil assemblage from the ?Anisian–Ladinian Quebrada de los F´osiles Formation (Puesto Viejo Group) in Mendoza, Argentina. Despite the limited sample size and low floral diversity, we identified a diverse array of plant-arthropod interactions representing four feeding guilds. Notably, these interactions—including marginal damage, piercing and sucking, galling, and oviposition—were restricted to the seed fern Ptilozamites, representing the first record of insect damage on this taxon from the Southern Hemisphere. The predominance of endophytic behaviors over generalized external feeding suggests that the thick cuticular layer of Ptilozamites could have acted as both a physical barrier to generalist herbivores and a shielded microenvironment for specialized insects, protecting the larvae against environmental stressors, such as volcanic activity, prevalent in this Triassic basin. Besides adding information about Middle Triassic plant-insect interactions to the overall scarce records from the Global South, our findings demonstrate that even small, localized assemblages can provide insights into the biotic relationships in terrestrial ecosystems during the Triassic recovery. Furthermore, this study reinforces previous observations that the apparent lack of Early and Middle Triassic Gondwanan interactions reflects a historical paucity of specialized studies rather than a genuine absence of ecological complexity in the Southern Hemisphere.