The emergence of vascular plants, such as Cooksonia, had a profound impact on Earth’s Early Paleozoic biogeochemical cycles (e.g. atmospheric oxygen, nitrogen and CO2), potentially triggering global environmental and biological changes. However, the timing of Cooksonia’s terrestrial emergence remains elusive as phylogenetic models, microfossils and macrofossils provide different timings for land colonization by vascular plants. Here, hundreds of zircon grains from three siltstones were dated using Laser Ablation-Inductively Couple Plasma-Mass Spectrometry (LA-ICP-MS). The study presents detrital zircon U-Pb dates, which refine the current biostratigraphy ages assigned to Cooksonia macrofossils from the three oldest sites globally. Specifically, siltstones hosting Cooksonia macrofossils from Borrisnoe Mountain (Ireland) and Capel Horeb (Wales) yield Gorstian–Homerian maximum depositional ages (MDAs) of 426 ± 2 Ma and 427 ± 2 Ma, respectively. Additionally, Cwm Graig Ddu (Wales) yields a (Pridoli-Ludlow) maximum age of 423 ± 3 Ma. The findings provide the first detrital zircon U-Pb dates for the oldest Cooksonia macrofossils globally and contribute crucial maximum ages. These maximum ages are instrumental in refining future calibrations of molecular clocks and improving phylogenetic models, thus contributing significantly to a better understanding of Cooksonia’s evolutionary history, including its environmental and ecological impacts.

This report presents survey and excavation results from the site of Río Chico, located near the city of Puyo, Ecuador. Currently, Río Chico is the oldest multicomponent village-type mound site of the Pastaza drainage, one of the great rivers of the Amazon basin. It is part of a series of monumental sites in the Upper Amazon of Ecuador but is unique in the area because of its evidence of consumption of certain plants and interregional trade.

The Meadowcroft Rockshelter in southwestern Pennsylvania is best known for its pre-Clovis occupation. Potentially important for later times is the recovery of maize macrobotanical remains from higher strata dating as early as the 4th century BC based on radiometric radiocarbon (14C) dates on wood charcoal. These remains have been considered to be potentially as old as the earliest microbotanical evidence for maize in Michigan, New York and Québec recovered from directly dated charred cooking residues adhering to pottery. The results of accelerator mass spectrometry (AMS) dating 17 samples from maize specimens from all Meadowcroft strata producing maize, indicate that the specimens originated from historical use of the shelter, most likely after AD 1800. These results further emphasize the need to obtain direct dates on maize macrobotanical remains recovered from early contexts prior to the development and common use of AMS dating.

This paper uses the decade-long collaboration between the Indian paleobotanist Birbal Sahni (1891–1949) and his Chinese doctoral student Hsü Jen (Xu Ren 徐仁, 1910–1992) to offer a connected history of mid-twentieth century scientific activity in China and India. Possibly the first Chinese scientist to earn a PhD from an Indian university (Lucknow, 1946), Hsü was certainly the first to be appointed to a faculty position in India. Sahni and Hsü's attempts to build Asian networks of scientific activity, characterized by the circulation of experts, scientific knowledge, and specimens, provide the grounds for considering a practice of Pan-Asianism. Such a formulation adds to existing work on the Pan-Asianist articulations of intellectual and political figures and urges for an expansion of how we understand scientific activity across China and India from the 1930s to the 1960s. In so doing, the paper makes two historiographical interventions. In the first instance, the collaboration presents an opportunity to move beyond the two dominant frames through which histories of science in China and India are studied: the nation state and Non-West/West binaries. Second, a focus on science widens the scope of China–India history, a field dominated by research on cultural, intellectual, and diplomatic topics.

Until now, availability of wood from the Younger Dryas abrupt cooling event (YDE) in N. America ca. 12.9 to 11.6 ka has been insufficient to develop high-resolution chronologies for refining our understanding of YDE conditions. Here we present a multi-proxy tree-ring chronology (ring widths, “events” evidenced by microanatomy and macro features, stable isotopes) from a buried black spruce forest in the Great Lakes area (Liverpool East site), spanning 116 yr at ca. 12,000 cal yr BP. During this largely cold and wet period, the proxies convey a coherent and precise forest history including frost events, tilting, drowning and burial in estuarine sands as the Laurentide Ice Sheet deteriorated. In the middle of the period, a short mild interval appears to have launched the final and largest episode of tree recruitment. Ultimately the tops of the trees were sheared off after death, perhaps by wind-driven ice floes, culminating an interval of rising water and sediment deposition around the base of the trees. Although relative influences of the continental ice sheet and local effects from ancestral Lake Michigan are indeterminate, the tree-ring proxies provide important insight into environment and ecology of a N. American YDE boreal forest stand.