The Paleocene Horse Creek florule, Tongue River Member of the Fort Union Formation, southeastern Montana, USA

We investigated leaf, cone and fruit impressions preserved in a siltstone deposit between coal seams the late Paleocene Tongue River Member near Otter, southeast Montana, to assess floristic diversity composition. document presence of Taxodium based on seed scales as well foliage branches associated pollen cones, low-diversity angiosperm assemblage about 15 genera dominated by Platanaceae (Platanus, Macginitiea, Macginistemon) Cornales (Cornus, Davidia, Amersinia, Browniea), cf. Trochodendraceae (Zizyphoides, Nordenskioeldia), augmented Aesculus, Trochodendroides, Ulmites Porosia. Most these were widespread Northern Hemisphere. The low this florule is consistent with that Tiffanian assemblages elsewhere Montana Wyoming. leaf known Phyllites demoresii Brown proposed likely candidate correspond extinct fruits called Porosia verrucosa (Lesquereux) Hickey emend. Manchester et Kodrul.