SUPPLEMENTARY MATERIAL 1 - EXPANDED METHODS Palynology Palynomorphs were recovered from samples using a modified standard palynological process in which carbonate and silicate minerals were removed with 10% hydrochloric acid followed by 48% hydrofluoric acid. Samples were then passed through a 100 sieve and the fine fractions containing organic microfossils were concentrated by centrifuging in lithium heteropolytungstate (2.1g/ml). Samples for light microscopy were oxidized with weak Schulze solution and acetolysis. Palynological processing also included the addition of exotic Lycopodium tablets to permit the calculation of palynomorph concentration. All residues were mounted in glycerine jelly. Specimens were observed with a Nikon Eclipse 80i microscope and imaged with a DXMF 1200 camera through a Plan Apo objective using Differential Interference Contrast where appropriate. Extended Depth of Field micrographs were created using Photoshop. Following Traverse (2007), 200 palynomorphs per sample were identified and counted (note, in some instances multiple samples from the same quarry were combined to reach 200) except in two instances, where 100 palynomorphs per sample were identified and counted (Table S3). Dinoflagellates were also identified concurrently but counted separately to the count of 200 palynomorphs. All identifications were made through consultation of the original descriptions and images. All residues and slides are housed in the Department of Paleobiology, National Museum of Natural History, Smithsonian Institution (see Table S2 for detailed locality data). Carbon Isotope Value of Pollen (  13 Cpollen) Pollen samples for isotopic analysis were initially treated with HCl and HF as above, but not oxidized. All processing was completed in double distilled water. Pollen grains were concentrated through sieving alone. A pollen-water slurry of each sample was placed on a microscope slide using a steel and glass syringe. Pollen grains of Cupressacites hiatipites Korasidis, V.A., et al., 2022, Reworked pollen reduces apparent floral change during the Paleocene- Eocene Thermal Maximum: Geology, v. 50, https://doi.org/10.1130/G50441.1