Malvaceae ( a , b ), Nothofagaceae ( c , d ), Nyctaginaceae ( e – k ). a Maxwellia lepidota Bail. (A: Guillaumin et Baumann 13129), New Caledonia. b Pentace laxiflora Merr. (A: Leopold 78602), Sandakan, Sabah. c , d Nothofagus antartica (Forst) Oerst. (MO 1971548: M. Gusinde 9), Isla Navarino, Argentina. e Abronia fragrans Nutt. ex Hook. (GH: Forwood 42), SE Idaho. f Ammocodon chenopodioides (Gray) Standl. (MO 5827773: Siegler, Hilu & May 8497), New Mexico. g Phaeoptilum spinosum Radlk. (BARC; A: Seydol 3199), Southwest Africa. h Detail of wing striation from g . i Selinocarpus diffusus A. Gray (MO 1744905: Reverchon 4283), Texas. j Tripterocalyx micranthus (Torr.) Hook. [ Tripterocalyx pedunculatus (Jones) Standl.] (GH: B.R. & C.B. Maguire 4799), Mohave Co., Arizona. k Enlargement of wing from j . showing lateral veins merging with fimbrial vein, interspersed by a reticulum of finer veins. Scales calibrated in mm 

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... curtisii is common in the silicified shales of Almont, North Dakota (Crane et al., 1990, p. 35, 36, Fig. 23a – g). Because the fruits are often preserved flattened in shale, they may at first appear to have only two lateral wings. Brown (1962) attributed one such specimen from the Paleocene of Alkali Butte, Wyoming to Ulmus (Brown, 1962, pl. 24, Fig. 17 as Ulmus rhamnifolia ; refigured here, Fig. 23j). However, transverse sections of permineralized specimens indicate that they bore three wings, one of which often remains hidden in the sediment behind the two wings exposed in the original fracture surface. This kind of triwinged fruit is superficially similar to those of extant Wimmeria (Celastraceae) as noted by Crane et al. (1990). However, the wings in Wimmeria and related genera have thicker, more widely spaced subparallel veins, and an intervening very fine reticulum of more or less isodiametric areoles, and a fimbrial vein (Fig. 5h – j). The fine, dense pattern of subparallel reticulate venation with fusiform areoles seen in these fossils, is similar to that observed in some Combretaceae, Dioscoreaceae, some Nyctaginaceae, and Polygonaceae. This pattern, in combination with a thin pedicel, lack of a fimbrial vein, presence of longitudinal veins over the locular area and the well inset intramarginal vein narrows the affinities to Polygonaceae. The well inset intramarginal vein is a feature shared, for example, with extant Parapteropyrum and Pteropyrum (Fig. 14e). Another example of Polygonaceae from the Paleocene of North Dakota is: Podopterus antiqua sp. n. Fig. 23h – m Holotype. FMNH-PP45598 (Fig. 23h, k – m). Paratype. YPM 54383 (Fig. 23i). Diagnosis. Fruits obovate with emarginate apex and cuneate base, 13 – 18 mm high, 8 – 10.5 mm wide, with three wings. The fruit body is an elliptical, single- seeded endocarp 2.5 – 3.3 mm wide to 3 – 4 mm high, subtriangular in cross section. The pedicel is narrow (ca 0.2 mm) and joins the base of the fruit without articulation. Wings chartaceous, with a dense anastomosing network of fine venation. Fimbrial vein lacking. A funnel-like fold of wing tissue representing part of the perianth occurs at the apex with three or more protruding filaments and or style remnants. This fruit type, which Brown (1962, referring to the specimen reillustrated here in Fig. 23j) considered to represent Ulmus , was treated by Crane et al. (1990) simply as “ biwinged fruit ” . More specimens have been collected since those publications, and it is now clear that the fruits were 3-winged rather than just two, as can be seen in obliquely fractured and tranversely sectioned (Fig. 23k) specimens. P. antiqua co- occurs with Polygonocarpus curtisii , but does not have intramarginal veins and has an acute rather than emarginate base. It corresponds closely in size and morphology and wing venation to extant Podopterus (Fig. 14g). Another example that apparently represents this genus is preserved in amber from the Miocene of Chiapas Mexico (Fig. 1.65 in Taylor et al., 2008). Fossil Malvaceae Fin-winged fruits of Craigia were widespread in the Tertiary of the Northern Hemisphere and have been traced to the Eocene in eastern Asia and western North America (Kva č ek et al., 2005). We have reexamined the type specimen of the species Berry (1930) assigned to Ptelea eocenica , from Grand Junction, Tennessee (Fig. 24a). The pedicel is much to thick to be that of Ptelea , however, and appears to have supplied a multivalved fruit. The pedicel is similar in thickness to, and has a similar perianth scar to the fruits of extant Craigia (Fig. 11h) and Maxwellia (Fig. 12a). The fusiform locular area, and organization of venation is also similar to these genera, but we hesitate to make a formal generic reassignment based on the single available specimen. Fossil Rhamnaceae Two specimens from the Eocene Green River Formation of Utah appear to represent a fin-winged fruit of Rhamnaceae similar to those of Gouania : Rainbowia gen. n. Rainbowia rhamnoides sp. n. Fig. 24b, c Holotype. DMNH 24492 (Fig. 24b). Paratypes. UF18054-22809 (Fig. 24c). Etymology. This genus is named for the town of Rainbow, Utah, situtated near the localities from which these fossils were collected. The species refers to the similarity with Rhamnaceae. Diagnosis. Fruit valves are cordate, with a retuse apex, base obtuse except for the narrowed, stipitate proximal end. Each valve or mericarp with two auriform wings spreading from an obovate thickened central body; veins irregular in course and spacing, with large areoles. One or two prominent intramarginal veins are connected by occasional straight to arched cross veins with the central body. The venation pattern on the wings of Rainbowia is very similar to that observed on those of extant Gouania , Crumenaria and Reisseika . The shape and size are similar to Gouania (Fig. 15e, g), however we did not observe any extant species with the sharply protruding base seen in these fossils. That feature could be an indication that these fruits belong to another family, and are only convergent in some of the features with Rhamnaceae, or it could represent an extinct morphological feature for fruits of Rhamnaceae. A more secure placement of this taxon may require a study of more fossil specimens, but currently these are the only two known. Fossil Rutaceae Although we have rejected some earlier assignments of fossil fruits to the genus Ptelea , we infer that the following species from the Eocene of western North America is a valid representative of the genus. Ptelea paliuruoides (Brown) comb. n. Fig. 24d – g Basionym. Carpolithus paliuroides Brown 1934, p. 67, pl. 15, Fig. 12. Description. Fruit orbicular to more or less cordate, with a cuneate obtuse to right- angle base and slightly retuse apex, (10 – )15 – 16 mm high and (10 – )15 – 19 mm wide, similar in height and width, with two (or more?) wings symmetrical about the median axis. In face view, a coarse vascular bundle extends straight from the pedicel to the style bisecting the locular area which is positioned near the center of the fruit. Each locule bearing at least one large elliptical smooth rounded seed (Fig. 24f). Pedicel, relatively narrow (0.2 mm thick) and 4 – 6 mm long. A thickened disk/perianth scar at junction between pedicel and fruit. A thin stylar protrusion, ca 1 mm long, sometimes persisting. A moderately strong, sinuous vein outlining the locular area. Venation across the wing irregularly sinuous, with smaller irregular cross veins forming subangular, more or less isodiametric polygonal areoles (Fig. 24d, e, g). Fimbrial vein present. Wing area dotted with dark spots, 10 – 20 μ m diameter. This species is based on rare fin-winged fruits from the Middle Eocene Parachute Creek Member of the Green River Formation of Colorado and Utah. The prominent scar at top of pedicel (Fig. 24d, e, g) indicates that this fruit developed from a hypogynous perianth. Candidate families with hypogynous perianth and fin-winged fruits with at least two wings include Zygophyllaceae, Sapindaceae, Malvaceae and Brassicaceae. Because only complete specimens have been found (no mericarps), we infer that the fruits were nonschizocarpic, which would rule out many Brassicaceae, Zygophyllaceae and Sapindaceae. The narrow pedicel distinguishes this fruit from most extant genera in these families, and indicates that this fruit was probably only bicarpellate and two winged, because a thicker pedicel would be required to vascularize a multicarpellate fruit. The fruit is similar to that of Brossardia (Brassicaceae, Fig. 4a), but that genus differs in having an inflated locular area that extends from the base of the fruit to near the apex. The locular area in this fossil is confined to the central portion of the fruit (as in extant Ptelea ) and does not appear ...