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Premise of research. Fossil infructescences of the late Paleocene Cyclocarya brownii (Juglandaceae) and winged fruits with newly recognized anatomical structure are described from Almont and Beicegel Creek, North Dakota. These fossils demonstrate that C. brownii has many similarities to extant Cyclocarya paliurus but differs in several morphological and anatomical features. Comparisons of the fossil record of Cyclocarya document the transition of characters in the evolution of the oldest extant genus of Juglandaceae. Methodology. Fossils were digitally imaged with reflected light microscopy (LM). Some specimens were embedded in Ward's Bio-Plastic synthetic resin, sectioned into wafers, mounted on microscope slides, and imaged with reflected LM. Permineralized specimens from the Beicegel Creek site were prepared with the cellulose acetate peel technique, mounted on microscope slides, and imaged with transmitted LM. Extant fruits of C. paliurus were photographed from freshly collected material. Pivotal results. Infructescences of C. brownii differ from those of modern C. paliurus in several ways. The fossils are racemes with crowded fruits borne on elongate pedicels. In contrast, extant C. paliurus has spikes bearing fewer fruits per infructescence (10 vs. 23). Fruit wall anatomy is similar to that of extant and other known fossil species of Cyclocarya but is more complex and has a distinctive idioblast layer not present in extant Cyclocarya. Fossil pollen is triporate in contrast to the tetraporate pollen in extant Cyclocarya. As in extant Cyclocarya , pollen is borne both in staminate catkins and occasionally in stamens attached to fruits. We document a fossil fruit with stamens bearing pollen. This feature, sporadic in extant Cyclocarya , was also present in the Paleogene. Conclusions. Late Paleocene C. brownii differs in comparison with extant C. paliurus and related fossil forms in infructescence architecture, fruit size and symmetry, fruit wall anatomy, and pollen aperture number. Trends in character evolution from the Paleogene to the present day include (1) changes from helically arranged, densely distributed pedicellate fruits to sessile fruits borne singly along a slender axis, (2) transition from pyramidal to round nutlets with (3) equatorial versus basal wing attachment, (4) a change in pollen aperture number from three to four, and (5) simplification of the fruit wall in extant Cyclocarya. [ABSTRACT FROM AUTHOR]

Paleosecuridaca curtisii Pigg, DeVore, and Wojciechowski gen. et sp. nov. (Polygalaceae) is described for anatomically preserved, nonschizocarpic, asymmetric samaras from the Late Paleocene (Tiffanian 3) Almont and Beicegel Creek floras of North Dakota. Paleosecuridaca is quite similar to the extant genus Securidaca L. (Polygalaceae) but has several distinctive features that warrant the establishment of a new genus. Fruits are 2.5- 3.6 cm long (x = 3:0 cm, n = 16) with a central ovoid nut 0.6-1.25 cm long (x = 0:9 cm, n = 26), 0.35-0.8 cm wide (x = 0:6 cm, n = 26), and 0.25-0.3 cm thick attached to a broad wing with a small secondary wing on its upper surface. The wing is vascularized by several veins running parallel to its long axis at the top and others in the main body of the wing arching downward and outward, with a few interreticulations occurring between the major veins. The nut contains a single, large locule with two well-developed seeds, each with a seed coat that has a prominent palisade layer like that of many extant genera of Polygalaceae. Specimens lack the broad attachment surface characteristic of Acer and instead have a short peduncle. Paleosecuridaca resembles the compressed fruit DeviacerManchester fromthe Paleogene of western NorthAmerica, Europe, and Asia and may be its anatomically preserved equivalent. The Late Paleocene Paleosecuridaca is the oldest-known megafossil representative of the Polygalaceae, a family now nested within the Fabales (sensu APG II) along with Leguminosae, Surianaceae, and QuillajaMolina on the basis of newmolecular data.Together with the earliest record of Leguminosae fromthe Late Paleocene ofWyoming, these samaras provide independent evidence for an earlier divergence of these two families. [ABSTRACT FROM AUTHOR]

Hamawilsonia boglei Benedict, Pigg & DeVore gen. et sp. nov. (Hamamelidaceae) is described from the Late Paleocene Almont flora of central North Dakota. The infructescence is an anatomically preserved spike with up to 20 sessile, robust, cuboidal to ovoid capsules borne on an elongate, thick axis up to 9.2 cm long × 0.5 cm wide. Individual fruits are 10-12 mm across and bilocular, with paired persistent, recurved styles borne on the distal carpel face. One locule is often larger than the other. Anatomically, the fruit wall is composed of a sclerified endocarp and a poorly preserved exocarp. Seeds are elliptical to slightly obovate with a sclerotic seed coat. Hamawilsonia is an extinct Late Paleocene genus with a combination of characters not seen in any extant hamamelid genus. Hamawilsonia is similar to the Asian endemic genus Sinowilsonia in its elongate spikelike infructescence, resembles the witch hazel Hamamelis in fruit and seed morphology, and has seed anatomy that combines features found in several extant genera. Affinities with Sinowilsonia are further supported by the co- occurrence of associated pollen catkins and in situ tricolpate pollen with a distinctive reticulate sculpturing. Like several other Almont taxa (Amersinia, Beringiaphyllum, Davidia, and Palaeocarpinus), Hamawilsonia is a genus with strong North American-Asian affinities. [ABSTRACT FROM AUTHOR]

Susiea newsalemae Taylor, DeVore & Pigg gen. et sp. nov. is described for distinctive seeds referable to the water lily family Nymphaeaceae from the Late Paleocene Almont Flora of central North Dakota, U.S.A. Seeds are oval to barrel shaped, 5 mm long × 3 mm wide, and have an apical operculum and a prominent lateral raphe. The outer surface of the seeds is composed of palisade, shinglelike cells 40 µm high × 150 µm wide with smooth cell margins lacking papillae. The operculum is 1 mm across and surrounded by a narrow furrow, covering the micropyle but not the hilum. The raphe and micropyle are separated by several cells. Several specimens have a small embryo cavity surrounded by a small area of presumed endosperm below the micropyle and a well-developed perisperm filling the rest of the seed cavity. Susiea seeds are most similar to those of extant Euryale but differ in features of the epidermal cells, seed coat, and raphe morphology. They also share some features with Nymphaea, Nuphar, and Victoria. Susiea appears distinct from the permineralized fossil seeds of the middle Eocene Allenbya from the Princeton chert, Nuphar wutuensis from the Eocene of China, and Nuphar cf. wutuensis from the same Almont beds. Susiea is the oldest fossil taxon of the Euryale lineage, extending the previous Oligocene record back to the Late Paleocene and documenting a significantly older age for the Euryale/Victoria clade that is clearly a derived lineage based on phylogenetic analyses of modern taxa. [ABSTRACT FROM AUTHOR]

Paleoactea nagelii Pigg & DeVore gen. et sp. nov. is described for a small, ovoid ranunculaceous fossil fruit from the Late Paleocene Almont and Beicegel Creek floras of North Dakota, USA. Fruits are 5–7 mm wide, 4.5–6 mm high, 10–13 mm long, and bilaterally symmetrical, containing 10–17 seeds attached on the upper margin in 2–3 rows. A distinctive honeycomb pattern is formed where adjacent seeds with prominent palisade outer cell layers abut. Seeds are flattened, ovoid, and triangular. To the inside of the palisade cells, the seed coat has a region of isodiametric cells that become more tangentially elongate toward the center. The embryo cavity is replaced by an opaline cast. This fruit bears a striking resemblance to extant Actaea, the baneberry (Ranunculaceae), an herbaceous spring wildflower of North Temperate regions. A second species, Paleoactaea bowerbanki (Reid & Chandler) Pigg & DeVore nov. comb., is recognized from the Early Eocene London Clay flora, based on a single fruit. This fruit shares most of the organization and structure of P. nagelii but is larger and has a thicker pericarp. This study documents a rare Paleocene occurrence of a member of the buttercup family, a family that is today primarily herbaceous, and demonstrates a North Atlantic connection for an Actaea-like genus in the Paleogene. [ABSTRACT FROM AUTHOR]

Palaeocarpinus dakotensis Manchester, Pigg, et Crane sp.n. (Coryloideae, Betulaceae) is described from the Late Paleocene Almont and Beicegel Creek floras of North Dakota based on infructescences with associated staminate catkins, pollen, and leaves. The well-preserved, silica-permineralized specimens provide both anatomical and morphological data for this widely distributed genus of the Northern Hemisphere Paleogene. Characters that were previously unknown for the genus are described from anatomically preserved specimens, supporting earlier suggestions that Palaeocarpinus combines features found separately in the extant Coryleae and Carpineae. Features of Coryleae include infructescences composed of cymes with paired nuts, each enclosed within two highly dissected bracts of equal size quite similar to those of some species of modern Corylus, and staminate catkins with four to six bifurcate stamens per bract. Similarly, there are four bifurcate stamens per bract in extant Corylus and four to six in Ostryopsis, whereas more numerous stamens are found in Carpinus and Ostrya. Other features, however, are characteristic of the Carpineae, including external longitudinal ribs on bracts, many fruits per infructescence, and small, ribbed nuts with vascular bundles lying outside the endocarp. Pollen from the stamens of associated catkins is triporate with a scabrate exine and apparently lacks opercula on the apertures, as in Corylus. Simple, cordate-based elliptical leaves with pinnate, craspedodromous secondary veins and serrate margins referred to Corylites sp. are also found in association and are thought to represent the same coryloid plant. The appearance of Palaeocarpinus in the fossil record apparently predates that of extant genera in the Coryloideae, and it is likely that Palaeocarpinus-like plants were the forerunners of both Coryleae and Carpineae. [ABSTRACT FROM AUTHOR]