Early Paleocene tropical forest from the Ojo Alamo Sandstone, San Juan Basin, New Mexico, USA

Earliest Paleocene megafloras from North America are hypothesized to be low diversity and dominated by long-lived cosmopolitan species following the Cretaceous-Paleogene (K/Pg) mass extinction. However, megafloras used to develop this hypothesis are from the Northern Great Plains of North America, and relatively little is known about floras from southern basins. Here, we present a quantitative analysis of an earliest Paleocene megaflora (<350 kyr after K/Pg boundary) from the Ojo Alamo Sandstone in the San Juan Basin (SJB), New Mexico. The megaflora, comprised of 53 morphotypes, was dominated by angiosperms, with accessory taxa composed of pteridophytes, lycophytes, and conifers. Diversity analyses indicate a species rich, highly uneven, and laterally heterogeneous flora. Paleoclimate estimates using multivariate and univariate methods indicate warm temperatures and relatively high precipitation consistent with a modern tropical seasonal forest. When compared to contemporaneous flora...北美古新世最早期巨型植物群（megaflora）被认为在白垩纪-古近纪（K/Pg）大灭绝事件后，呈现出多样性偏低且以长寿广布种为优势类群的特征。然而，支撑该假说的巨型植物群数据均采自北美大平原北部，而南部盆地的植物群研究相对匮乏。本研究针对新墨西哥州圣胡安盆地（SJB）奥乔阿拉莫砂岩中的古新世最早期巨型植物群（距K/Pg界线不足35万年）开展定量分析。该巨型植物群包含53个形态种，以被子植物占绝对优势，伴生类群涵盖蕨类植物、石松类植物与裸子植物。多样性分析结果表明，该植物群物种丰富、分布极不均匀且具有横向异质性。通过多变量与单变量方法开展的古气候重建结果显示，当时气候温暖、降水相对充沛，与现代热带季节性森林的气候条件相符。当与同期植物群进行对比时……