Extinct lineages in a rift landscape: Middle Jurassic Bennettitales from the Otlaltepec Formation

Abstract The Bennettitales, a group of extinct gymnosperms, had outstanding species diversity throughout the Mesozoic and were abundant during the Jurassic. They were key components of terrestrial ecosystems, thriving in diverse climates and environmental conditions. However, a deeper understanding of the ecological strategies exhibited by this extinct lineage across time and space within a well-characterized geological context is still lacking for the region. Here, we examine bennettitalean assemblages from the Middle Jurassic Otlaltepec Formation (Otlaltepec Basin) and compare them with floras from two other rift basins (Tlaxiaco and Ayuquila) in low latitudes. Based on morphological features, we propose the new species Zamites ambigua , and identify the following additional taxa: Zamites lucerensis , Zamites oaxacensis , Zamites tribulosus , cf. Zamites diquiyui , Zamites sp. 1, Zamites sp. 2, Bennettitcarpus sp. 1, Bennettitcarpus sp. 2, and cf. Weltrichia xochitetlii , along with two types of gymnosperm foliage of uncertain affinities. Our findings on bennettitalean diversity in the Otlaltepec Formation reveal the presence of foliage across all three basins in both time and space, indicating a generalist element among these rift environments. In contrast, other foliage and reproductive structures exhibit two distinct distributional patterns: some are confined to a single basin over time, while others appear only during specific intervals in each basin’s history. Our findings highlight that some Bennettitales exhibited ecological resilience, maintaining their morphology and distribution despite the shifting environmental conditions caused by tectonic activity. This suggests that certain generalist taxa persisted across varying moisture regimes and depositional settings, while others displayed more localized or temporally restricted distributions.