Mapping monstrosity: Malformed sporomorphs across the Smithian/Spathian boundary interval and beyond (Salt Range, Pakistan)

Abstract

In the last 500 million years, Earth's biota experienced periods of crises with extinctions on a large scale and significant turnover events, one of them being the Permian-Triassic extinction event. The following Early Triassic was a critical time marked by a series of biological and environmental changes with a complex recovery pattern of marine faunas and ecosystems. Generally, animals and plants respond to stress by using different strategies that help them tolerate or recover from unfavourable environmental conditions. In this contribution, we quantitatively and qualitatively describe a variety of malformations of spores and pollen grains from the extensively studied Nammal section (Salt Range, Pakistan) across the Smithian/Spathian boundary interval (Early Triassic). High dominance of malformed sporomorphs is recorded throughout the studied interval, indicating stressful conditions for plants on the Indian margin during the Early Triassic. One of the highest abundances of malformed sporomorphs coincides with the spore spike and the negative carbon isotope excursion during the middle Smithian, emphasising this intense biotic stress. Either a cocktail of volcanic gases, acid rains, soil acidification, and heavy metal pollution as a consequence of a late pulse of the Siberian Trap large igneous province or climatic extremes might have been responsible for these malformations. Here teratology is used as a tool/means to assess the severity of biotic crises in the plant kingdom, indicating its potential value as a signal of ecological disturbance. • Fossil spores and pollen morphology as a proxy for ancient environmental pollution. • Sporomorphs identification schemes to quantify morphological change. • Evaluation of possible causes triggering morphological variation in sporomorphs.