Chaneya, a New Genus of Winged Fruit from the Tertiary of North America and Eastern Asia

A new genus is recognized on the basis of wind-dispersed fruits from the Eocene of western North America and Miocene of eastern Asia. The fruits consist of an accrescent hypogynous calyx of five obovate sepals and one or more globose fruit bodies. Although the fossils were formerly placed in the extant genera Porana (Convolvulaceae) and Astronium (Anacardiaceae), our investigation of numerous specimens from several floras in the western United States (e.g., Florissant, Green River, Clarno) and Canada (Whipsaw Creek, British Columbia) and the Yilan and Shanwang floras of China reveals unique characters that indicate that the fossils are a distinct genus, which we name Chaneya. Unlike Porana and Astronium, the fossil calyces have stomata that are longitudinally aligned, and early stages of fruit development show a gynoecium of five apocarpous carpels, of which only one or two usually enlarge at maturity. Precise systematic placement of the fossil genus is uncertain, but similarities to the extant Picrasma of the Simaroubaceae are suggestive of possible affinities. Two species are recognized: Chaneya tenuis (Lesq.) comb. nov., from the Eocene of western North America and northeastern China, and Chaneya kokangensis (Endo) comb. nov., from the Miocene of eastern Asia.     

ATTACHED LEAVES,INFLORESCENCES, AND FRUITS OF FAGOPSIS,AN EXTINCT GENUS OF FAGACEOUS AFFINITY FROM THE OLIGOCENE FLORISSANT FLORA OF COLORADO,U.S.A.

Specimens showing staminate and pistillate inflorescences attached to branches bearing Fagopsis longifolia (Lesq.) Hollick foliage, from the Oligocene Florissant flora of Colorado, permit a relatively complete characterization of the extinct Fagopsis plant. The alternately arranged simple leaves have pinnate craspedodromous venation and prominent simple teeth. Staminate inflorescences are globose on a stout peduncle and contain anthers with tricolporate pollen. Pistillate inflorescences are ovoid heads with compact, helically arranged three-flower units and are interpreted to have three styles per flower. The infructescence consists of small wedge-shaped cupules, each containing three tiny fruits, and subtended by a persistent bract. The cupules unravel from the swollen peduncle at maturity and are often dispersed as strings of adhering fruit-wedges which frequently take on a regular, more or less circular appearance. Fagopsis is unlike any living genus but has characters which support a relationship to the Fagaceae. Unlike extant members of the family, which typically have fruits adapted for animal dispersal, Fagopsis is less obviously specialized and perhaps adapted for wind dispersal. The striking differences in fruiting structures between Fagopsis and extant Fagaceae parallel the differences between the extant genera Platycarya and Juglans in the Juglandaceae, and Alnus and Corylus in the Betulaceae.     

FOSSIL CERATOPHYLLUM (CERATOPHYLLACEAE) FROM THE TERTIARY OF NORTH AMERICA

Fossil fruits and a vegetative axis assignable to the extant genus Ceratophyllum are described from four North American Tertiary localities. Fossil fruits assignable to the extant species C. muricatum and C. echinatum are reported from the Eocene Green River and Claiborne formations, and the Miocene Esmerelda Formation, respectively. An extinct species, C. furcatispinum, is described from the Paleocene Fort Union Formation and represents the oldest published report of Ceratophyllum in the fossil record. The existence of extant angiosperm species in the Eocene is very unusual and may be attributable in this case to slow evolutionary rates and unusual evolutionary properties associated with hydrophily in the genus Ceratophyllum.     

The fossil record of Eucommia (Eucommiaceae) in North America

Reproductive and vegetative remains of Eucommia from 25 localities in the United States, Canada, and Mexico document the wide distribution of this genus in North America during the Cenozoic. Autofluorescent elastic latex filaments bearing capitate termini are preserved in nearly all of the remains and provide conclusive evidence of their affinity to Eucommia. Four species of Eucommia are recognized on the basis of the characteristic samaras: E. eocenica from middle Eocene strata of the Mississippi Embayment in Missouri, Tennessee and Mississippi; E. montana from early Eocene to early Oligocene localities in British Columbia, Washington, Oregon, Utah, Colorado, and Montana; E. constans from Neogene rocks in central Mexico; and E. jeffersonensis n. sp. from the latest Eocene or earliest Oligocene John Day Formation of Oregon. Atypical specimens of E. montana and E. eocenica are the first records of two-seeded fruits for the genus. Eucommia leaves from Eocene localities in British Columbia and Mississippi are the first records of Eucommia foliage in North America whose identifications are confirmed by the presence of capitate latex strands. These leaves and a specimen from Oregon are referred to E. rolandii n. sp. Fruit evolution in Eucommia may have involved increases in samara size and symmetry, and reduction in seed number from two to one, perhaps as adaptations for wind dispersal. All fossil Eucommia samaras from North America are smaller and less symmetrical than those of the living species, E. ulmoides. Preliminary flight tests of E. ulmoides samaras and of models of the fossils suggest that E. ulmoides fruits are aerodynamically better suited for wind dispersal than the fossils.     

FOSSIL EXTRAFLORAL NECTARIES,EVIDENCE FOR THE ANT-GUARD ANTIHERBIVORE DEFENSE IN AN OLIGOCENE POPULUS

Extrafloral nectaries are secretory glands, usually found on leaves, that have been shown to promote ant defense against the insect herbivores of many modem day plants. Extrafloral nectaries were found on the 35-million-year-old fossil leaves of the extinct Populus crassa from Florissant, Colorado. Extinct ant species (belonging to five still extant genera that have modem ant-guard species), and other predators and parasitoids (whose modem relatives frequent extrafloral nectaries) also lived at Florissant. The extrafloral nectaries of P. crassa (and perhaps other plants) probably operated to attract ants and/or other arthropod defenders as early as the Oligocene.     

A new species of Zelkova (Ulmaceae,Ulmoideae) with leaves and fruits from the Oligocene of South China and its biogeographical implications

A new fossil species of Zelkova is described from the Oligocene Ningming Formation of Guangxi, South China. Zelkova ningmingensis sp. nov. is characterized by leaves with craspedodromous venation pattern and drupaceous fruit type. The new species possesses elliptical to ovate leaves, bearing 7–12 pairs of secondary and simple toothed margin, as well as epidermal cells with straight or rounded anticlinal walls. The species is compared with extant and other fossil species hitherto reported of the genus. It is most similar to the living Zelkova schneideriana in the leaf gross morphology and epidermal characters, which may be suggested to be the ancestral type of Zelkova schneideriana. The discovery of Zelkova ningmingensis sp. nov. in Guangxi indicates that Zelkova has already existed in southern China as early as the Oligocene. In combination with Zelkova material from the Oligocene of Europe, it can be inferred that Eurasian Zelkova had begun to diversify by at least the Oligocene. Because China is the biodiversity centre of modern Zelkova, the fossil herein provides new insights into Zelkova biogeography.     

INTERCONNECTED REPRODUCTIVE AND VEGETATIVE REMAINS OF POPULUS (SALICACEAE) FROM THE MIDDLE EOCENE GREEN RIVER FORMATION,NORTHEASTERN UTAH

A new specimen from the Middle Eocene Evacuation Creek Member of the Green River Formation in northeastern Utah shows a twig with several leaves of Populus wilmattae Cockrell and a fruiting raceme attached. This specimen establishes for the first time the type of fruits borne by P. wilmattae and provides additional characters with which to assess its taxonomic and evolutionary status. An associated seed shows attached placental hairs like those of extant species of Populus. The Green River fossil differs from extant Populus species in having basically palmate leaf venation and in bearing its fruiting axis on a young twig. In other aspects, the fossil species is remarkably similar to the extant species Populus mexicana.     

Winged Fruits of Deviacer in the Oligocene from the Ningming Basin in Guangxi,South China

Deviacer guangxiensis Chen & Manchester sp. nov. is described based on asymmetric samaras from the Oligocene Ningming Formation in Guangxi, South China, representing the first documentation of Deviacer fossils in Asia. The Oligocene species, with relatively large fruits, represents the youngest record of the genus so far known; all other records are from the Paleocene and Eocene, or late Eocene—early Oligocene in western North America and Europe. It indicates that the extinct genus, Deviacer, was widely distributed in the northern hemisphere during the Paleogene.     

A combined light and scanning electron microscopy study

The uppermost Eocene Florissant Formation, Rocky Mountains, Colorado, has yielded numerous insect, vertebrate and plant fossils. Three previous comprehensive palynological studies investigated sections of lacustrine deposits of the Florissant Formation and documented the response of plant communities to volcanic eruptive phases but overall found little change in plant composition throughout the investigated sections. These studies reported up to 150 pollen and spore phenotypes. In the present paper, we used a taxonomic approach to the investigation of dispersed pollen and spores of the Florissant Formation. Sediment samples from the shale units containing macrofossils were investigated using light microscopy (LM) and scanning electron microscopy (SEM). The general picture of the palynoflora is in agreement with previous studies. However, the combined LM and SEM investigation provides important complementary information to previous LM studies. While a fairly large amount of previous pollen determinations could be confirmed, the purported taxonomic affinities of several pollen phenotypes need to be revised. For example, pollen referred to as Podocarpus or Podocarpidites sp. belongs to the Pinaceae Cathaya, Malus/Pyrus actually belongs to Dryadoideae, pollen of the form genus Boehlensipollis referred to as Proteaceae/Sapindaceae/Elaeagnaceae or Cardiospermum belongs to Sapindaceae but not to Cardiospermum, and pollen of Persicarioipollis sp. B with previously assumed affinities to Polygonaceae actually belongs to Thymelaeaceae. Pandaniidites and one type of Malvacipollis cannot be linked with Pandanaceae and Malvaceae. A few taxa are new records for Florissant (Ebenaceae: Diospyros; Mernispermaceae; Trochodendraceae: Tetracentron). In general, SEM investigations complement the LM palynological studies and improve the identification of dispersed pollen and spores and enable integration of data from dispersed fossil pollen into a wide range of comparative morphological, taxonomic, evolutionary, biogeographic and phylogenetic studies.     

An extinct genus of Salicaceae based on twigs with attached flowers, fruits, and foliage from the Eocene Green River Formation of Utah and Colorado, USA

A newly recovered twig with attached leaves and flowers from the Eocene Green River Formation of Utah provides the basis for recognizing a new, extinct genus of Salicaceae sensu lato (s.l.). Pseudosalix handleyi gen. et sp. nov. has alternate lanceolate leaves with pinnate, semicraspedodromous venation and a serrate margin with glandular teeth. The inflorescence is terminal on the twig and is unisexual, composed of flowers organized in a paniculoid cyme, with lateral paraclades of pedicellate flowers. The attached pistillate flowers have four prominent sepals that are valvate in bud, spreading but basally fused at anthesis; the single pistil of each flower is ovoid with three or four longitudinal sutures, indicating development to a capsular fruit. Three or four recurved styles radiate from the apex of the pistil, each with a distal globose stigma. The infructescence, verified by attachment to twigs with the same kind of leaves, bore capsular fruits of three and four valves. Associated but unattached, staminate flowers also have four well-developed, basally connate sepals. They are pedicellate and bear several stamens, each with a short filament and globose anther. The available morphological characters place the fossil species within the Salicaceae s.l. as an immediate sister to the clade containing Populus and Salix. Although the likely outgroup genera (including Itoa, Poliothyrsis, Carrierea, and Idesia) to tribe Saliceae all occur in Asia today and not North America, the occurrence of both Pseudosalix and Populus in the Eocene of Utah raises the possibility of a North American origin for the Saliceae.     

CIBOTIUM OREGONENSE: AN EOCENE TREE-FERN STEM AND PETIOLES WITH INTERNAL STRUCTURE

Cibotium oregonense sp. nov. is described from the Upper Eocene of Medford, Oregon. The fossil comprises petiole bases and stem periphery of a large fern preserved via permineralization. A stele devoid of sclerenchymatous sheathing and a petiole vascularized with a large number of leaf traces in a cyatheacean pattern characterize the fossil. A distinctive U-shaped interior series of leaf traces allows assignment to the genus Cibotium. This fossil provides evidence that the genus Cibotium was represented by an arborescent species with large leaves in the Early Tertiary of western North America.     

Morphological and Behavioral Convergence in Extinct and Extant Bugs: The Systematics and Biology of a New Unusual Fossil Lace Bug from the Eocene

The bug Gyaclavator kohlsi Wappler, Guilbert, Wedmann et Labandeira, gen. et sp. nov., represents a new extinct genus of lace bugs (Insecta: Heteroptera: Tingidae) occurring in latest early Eocene deposits of the Green River Formation, from the southern Piceance Basin of Northwestern Colorado, in North America. Gyaclavator can be placed within the Tingidae with certainty, perhaps it is sistergroup to Cantacaderinae. If it belongs to Cantacaderinae, it is the first fossil record of this group for North America. Gyaclavator has unique, conspicuous antennae bearing a specialized, highly dilated distiflagellomere, likely important for intra- or intersex reproductive competition and attraction. This character parallels similar antennae in leaf-footed bugs (Coreidae), and probably is associated with a behavioral convergence as well.     

INVESTIGATIONS OF ANGIOSPERMS FROM THE EOCENE OF NORTH AMERICA: A CATKIN WITH JUGLANDACEOUS AFFINITIES

Three specimens of one type of fossil catkin from the Middle Eocene of Tennessee are excellently preserved and have been investigated morphologically. The flowers on these catkins are subtended by elongate, three-lobed bracts, are exclusively staminate, and have three conspicuous, obovate, perianth parts that bear large peltate scales. The stamens are well preserved and contain triporate pollen grains that are equivalent to the dispersed pollen genus Momipites. Floral morphology, cuticular features, and pollen indicate close affinities with the extant genera Engelhardia, Oreomunnea, and Alfaroa of the Juglandaceae; but because the fossil catkins are distinct and are a dispersed plant organ, they are placed in a new form genus: Eokachyra. These fossil flowers represent a rare opportunity to correlate the micro- and macrofossil record and to compare the relative rates of evolution of these features. The fossil catkins also demonstrate that much structural information may be gained from the study of fossil angiosperm flowers. The similarities between the staminate flowers of the fossil catkins and the staminate flowers of Engelhardia, Oreomunnea, and Alfaroa confirm the idea that this complex has had a long evolutionary history and suggest that the pollination system of certain extant genera was well developed during Middle Eocene times.     

ANGIOSPERM FLOWERS AND TRICOLPATE POLLEN OF BUXACEOUS AFFINITY FROM THE POTOMAC GROUP (MID-CRETACEOUS) OF EASTERN NORTH AMERICA

A new genus of fossil angiosperms (Spanomera gen. nov.) is established for flowers from two localities in the mid-Cretaceous Potomac Group of Maryland, eastern North America. The type species, Spanomera mauldinensis sp. nov., from the early Cenomanian Elk Neck beds, has inflorescence units with terminal pistillate, and lateral staminate flowers. The organization of inflorescences and flowers is opposite and decussate. Staminate flowers typically have five tepals: two lateral, one posterior, and two in the anterior position. Each tepal is opposed to a stamen with a short filament, dorsifixed anther, and two pairs of pollen sacs. Stamens contain pollen comparable to the dispersed pollen species Striatopollis paraneus (Norris) Singh. Pistillate flowers have two lateral tepals and two anterior-posterior tepals that are opposed to two carpels. Carpels are slightly fused basally along their ventral margins and are semicircular in outline with a long, decurrent, papillate ventral stigma. Frequently this stigmatic surface has abundant attached pollen of the Striatopollis paraneus type. Spanomera marylandensis sp. nov., from the late Albian Patapsco Formation, is similar to S. mauldinensis but is known only from isolated flowers and floral parts. Staminate flowers have four stamens with dorsifixed anthers and each is opposed to a tepal. Stamens contain pollen comparable to the dispersed pollen species Striatopollis vermimurus (Brenner) Srivastava. Carpels have pollen of S. vermimurus on the stigma. Spanomera provides further evidence of unisexual but probably insect-pollinated flowers among mid-Cretaceous, early nonmagnoliid (“higher”) dicotyledons, and is interpreted as closely related to extant Buxaceae. Characters that Spanomera shares with other taxa suggest that the Buxaceae themselves may be closely related to Myrothamnaceae and other “lower” Hamamelididae.     

A Review of the Fossil Record of the Genus Itea (Iteaceae, Saxifragales) with Comments on its Historical Biogeography

Itea is a genus of about 20 species of trees and shrubs that are today native to southeastern North America, eastern Asia, and eastern Africa. In this paper, I review the fossil record of Itea, which is based on four types of fossils: diporate, psilate pollen attributed to Itea or the dispersed pollen genus Iteapollis; carpofossils representing fruits and seeds attributed to Itea europaea; flowers preserved in amber and assigned to Adenanthemum iteoides; and leaf impressions attributed to Itea. The distributions of these fossils indicate that Itea was present in western North America from the early Eocene to Miocene, in eastern North America beginning no later than the early Miocene, and in western Eurasia from the late Eocene to Pliocene. Only one datapoint is known from eastern Asia; it is early Miocene in age. Based on the fossil record, it can be inferred that Itea crossed between continents over both the Bering Land Bridge and North American Land Bridge, and that it reached Africa from Europe via Anatolia. Thus, it is predicted that the sole extant North American species, I. virginica, may be most closely related to the sole extant African species, I. rhamnoides. The potential application of Itea fossils to calibrating phylogenetic trees generated from molecular sequence data is also discussed.     

EOCENE FLORAL EVIDENCE OF LAURACEAE: CORROBORATION OF THE NORTH AMERICAN MEGAFOSSIL RECORD

Numerous megafossils of Lauraceae have been reported from the early Tertiary of North America, but the subfamilial affinities are usually not well understood due to the great morphological variability found in extant taxa. The flowers of Androglandula tennessensis gen. et sp. nov. Taylor, from the Middle Eocene Claiborne Formation, are six-parted, pedicellate, bracteate, and have stamens with paired basal staminal glands. The flowers have ethereal oil cells and paracytic stomates throughout. The fossil species has affinities with the subtribe Cinnamomineae, and this supports suggestions that the Middle Eocene climate of the southeastern U.S. was subtropical. The existence of this fossil, and reports of the subtribe from the Eocene of Europe, indicate a South American-North American-European-southeast Asian paleodistribution suggesting that extinction in North America and Europe was the cause of the tribe's current disjunct distribution.     

BOTANICAL AFFINITIES OF SOME TRIPROJECTACITES FOSSIL POLLEN

During Late Cretaceous to Oligocene times, fossil pollen of the Triprojectacites group (also known as Aquilapolles or triprojectates), comprised a temporally and environmentally distinctive element of palynofloras in eastern Asia and western North America. Several species of this group serve as biostratigraphic index fossils for this interval. Using electron microscope and numerical analyses, primarily of North American triprojectate pollen, it is possible to recognize the presence of three distinct subgroups. One group, corresponding to the fossil genus Mancicorpus, has no morphologically close modern representative. Characters resembling those in Santalaceae (Santalales, Rosidae) occur in the second group, which is represented by a previously underscribed fossil triprojectate genus. The third group contains retipilate, isopolar pollen and strioreticulate, isopolar pollen. Forms exhibiting the latter morphology are commonly assigned to the genus Integricorpus, while the retipilate morphology characterizes another underscribed genus. This third group may have some phylogenetic connection to Apiaceae (Apiales, Asteridae). Pollen of some other extant families exhibits triprojectate features, although no close fossil representative can be presently identified. The triprojectate morphology is thus interpreted in modern and fossil forms as resulting from convergence rather than close phylogenetic relationships at the group level.     

CAESALPINIA SUBGENUS MEZONEURON (LEGUMINOSAE,CAESALPINIOIDEAE) FROM THE TERTIARY OF NORTH AMERICA

Legume fruits from the Eocene of Tennessee and Wyoming and the Miocene of Idaho are described and assigned to Caesalpinia subgenus Mezoneuron (Caesalpinioideae), an extant Paleotropical taxon that does not occur in North or South America today. Morphological and anatomical details of the fruits are used in evaluating their systematic relationships. The features of the fossil fruits are accommodated only within this extant subgenus. These fossils represent the only reliable known occurrence of C. subgenus Mezoneuron in the paleobotanical record. These fossils suggest that subgenus Mezoneuron was distinct from subgenus Caesalpinia by the Middle Eocene. Further, they document the widespread occurrence of this currently Paleotropical group for at least 30 million years in North America.