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THE PLATYCARYA PERPLEX AND THE EVOLUTION OF THE JUGLANDACEAE
Abstract
We report on the leaves, fruits, inflorescences, and pollen of two fossil species in the genus Platycarya. The association of these dispersed organs has been established by their repeated co‐occurrence at a large number of localities, and for two of the organs (fruit and pistillate inflorescence, and pollen and staminate inflorescence) by apparent organic attachment of compression fossils. Each of the two species can be distinguished by characteristics of all the known megafossil organs. We also review the fossil record of dispersed platycaryoid fruits and inflorescences, recognizing three additional species of Platycarya and two of Hooleya. Two of the fossil Platycarya species are morphologically very different from the living Platycarya strobilacea Sieb. et Zucc., but they show the diagnostic features of the genus. Hooleya is a generalized member of the Platycaryeae that is probably close to the ancestry of Platycarya.
The two Platycarya species known from multiple organs provide a remarkable example of mosaic evolution in which fertile and foliar structures have attained different levels of morphological specialization. The leaves, often considered the most plastic of plant organs, retain several features that are otherwise seen only in the Engelhardieae. These similarities in leaf architecture between the fossil Platycarya species and Engelhardieae are advanced features for the Juglandaceae, and thus indicate a sister‐group relationship between the two lines. In contrast to the leaves, the fruits, inflorescences, and pollen of the fossil Platycarya species are almost as specialized as those of the extant P. strobilacea and bear little resemblance to the same structures in other genera of the family.
The morphology, taphonomy, sedimentary setting, and geographic and stratigraphic distribution of three of the fossil platycaryoid species suggest that they were wind‐dispersed, early successional plants that grew in thickets. This habit is retained by Platycarya strobilacea and is typical of many of the amentiferae (e.g. Myricaceae, Betulaceae). The r ‐selected life‐history pattern of the Platycarya line may well have contributed to its low diversity through geologic time.
... Extensive fossil records are available for Juglandaceae, including woods, leaves, pollen, inflorescence, and fruits, covering most extant genera and many extinct groups (Manchester and Dilcher, 1982;Wing and Hickey, 1984;Manchester, 1987Manchester, , 1989Manchester, , 1991Manchester, , 1994Manchester, , 2000Manchester et al., 1994;Jin, 2009;Collinson et al., 2010;Sakala and Gryc 2011;Meng et al., 2015;Chen et al., 2018;Huegele and Manchester, 2019). Except for fruits, other characters for distinguishing genera in Juglandoideae may be difficult because of overlapping characteristics (Manchester and Dilcher, 1982). ...
... In this study, Platycarya is robustly resolved as sister to Juglandeae, and then the Platycaryeae-Juglandeae clade is sister to Hicoreae (Fig. 2). A relatively long branch of the Platycarya lineage was observed, implying its long evolutionary history within the family, which is in agreement with previous population genetic studies (Chen et al., 2012;Wan et al., 2017) and fossil records (Wing and Hickey, 1984). Furthermore, the same topology was obtained with our plastid data (BS ML = 100, PP BI = 1.00, ...
... Platycarya was often considered to possess many primitive features such as female and male flowers on the same spike, a large free and unspecialized floral bract with small bracteoles, and carinal stigmas (Leroy, 1955;Manning, 1938Manning, , 1940Manning, , 1978Endress, 1986). Platycarya also has some unique morphological features including the strongly scented inflorescences, densely packed flowers, relatively small stigmas, sticky pollen grains, and some wood characters (Wing and Hickey, 1984;Manos and Stone, 2001). The chromosome number (x = 15) in Platycarya also separates the genus from most other members of Juglandaceae (x = 16; Oginuma, 1999). ...
... In particular, the opposite percurrent, straight to sinuous tertiaries and their perpendicular to obtuse junctions with subjacent secondaries are clearly but faintly visible ( Figure 5.2, 5.3). Despite the preservation, this fossil demonstrates the defining characteristics of Platycarya foliage (Wing and Hickey 1984; extant Platycarya may have simple or compound leaves depending on species). Pollen of this genus is also found in the same sediments (Frederiksen 1998;Harrington, 2003a). ...
... Pollen of this genus is also found in the same sediments (Frederiksen 1998;Harrington, 2003a). The specimen corresponds best to the Eocene Western Interior taxa P. americana (Hickey 1977) and P. castaneopsis (Lesquereux) Wing and Hickey (1984), whose leaves have many differences with living Platycarya but whose fruits and seeds are generically diagnostic (Wing and Hickey 1984). Due to preservation, one character found in Platycarya leaves, the ascending vein from sinus to superjacent tooth (Wing and Hickey 1984), was not observed. ...
... Pollen of this genus is also found in the same sediments (Frederiksen 1998;Harrington, 2003a). The specimen corresponds best to the Eocene Western Interior taxa P. americana (Hickey 1977) and P. castaneopsis (Lesquereux) Wing and Hickey (1984), whose leaves have many differences with living Platycarya but whose fruits and seeds are generically diagnostic (Wing and Hickey 1984). Due to preservation, one character found in Platycarya leaves, the ascending vein from sinus to superjacent tooth (Wing and Hickey 1984), was not observed. ...
The U.S. Gulf Coast has an extensive but poorly dated paleobotanical record. A fossil locality behind the former Red Hot Truck Stop in Meridian, Mississippi, is well-known for its unusually rich biota of late Paleocene and early Eocene mammals, fish, snakes, mollusks, and plants. The latter include palynomorphs, fruits, and leaves, which are found in the basal Bashi Formation and are studied here for the first time. Though generally not well-preserved, the Red Hot leaf flora is significant because it is reliably dated to the first e11.6 million years of the Eocene and possibly lies within the Paleocene-Eocene Thermal Maximum; in contrast, nearly all other Eocene Gulf Coast macrofloras are middle Eocene or uncertain in age. We recognize 18 leaf species and morphotypes, including Lygodium kauffussi (a climbing fern), and representatives of Lauraceae (laurel family), Myrtaceae (guava family), Fabaceae (legumes), Platycarya (Juglandaceae, walnut family), Rhus (Anacardiaceae, sumac family), and a new genus and species of Ochnaceae (ochna family), all consistent with a tropical to subtropical climate. Additionally, two dispersed cuticle morphotypes are described that probably represent a monocot and a liverwort. The occurrence of Platycarya is the first macrofossil record of this Eocene index taxon from the eastern USA and corroborates pollen occurrences from the same strata. The Ochnaceae specimens are currently the only reliable leaf fossils of this distinctly tropical group with ∼30 genera and ∼500 species today; due to their significance, we assign them to a new taxon, Rhabdophyllites diapyros gen. et sp. nov. Most of the recognizable plant taxa are present at, or near, this time in the well-dated sequences of the Rocky Mountain region, indicating their wide North American distribution. The Red Hot flora shows the potential to build a well-dated record of Paleogene floras on the Gulf Coast, improving understanding of plant migration and evolution.
... A summary of previous paleoclimatic analyses is shown in Table 1. Several papers on plant macrofossils have addressed the systematics and paleoecology of portions of the paleoflora (Brown, 1962;MacGinitie, 1969;Dilcher, 1982, 1997;Wing and Hickey, 1984;Manchester, 1987;Manchester and Zavada, 1987;Herendeen et al., 1990;Herendeen and Dilcher, 1991;Manchester and Chen, 1996;Gemmill and Johnson, 1997;Wilf et al., 1998a;Wilf and Labandeira, 1999). Extended discussion of previous work and stratigraphy, descriptions and photographs of many of the fossil plant species, and locality and lithologic data can be found in Wilf (1998). ...
... Nearly all of the species recovered for sample 6 were found at two previously known localities in the upper 27 m of the Niland Tongue in the northern Great Divide Basin ( Fig. 1) (see Pipiringos, 1961;Wing and Hickey, 1984, Table 3). The Niland Tongue is Lostcabinian (Gazin, 1965;Roehler, 1987;Krishtalka et al., 1987). ...
... 2). The increase in Platycarya pollen abundance in the Main Body mirrors the contemporaneous increase in the Bighorn Basin, which may be related to rising temperatures (Fig. 2;Wing and Hickey, 1984;Roehler, 1992c). ...
The warmest global temperatures of the Cenozoic Era occurred in early Eocene time, following a warming trend that started in late Paleocene time. The greater Green River Basin of southwestern Wyoming is one of the best areas in the Rocky Mountains for paleobotanical investigation of the Paleocene-Eocene climatic transition. Intensive sampling has resulted in the recovery of an estimated 189 species of plant macrofossils from the Tiffanian, Clarkforkian, Wasatchian, and Bridgerian land mammal "ages." The leaf morphologies and taxonomic affinities of these fossils were used in combination with other indicators to evaluate Paleocene-Eocene climates. Following cool humid conditions in the Tiffanian, the Clarkforkian was humid and subtropical, and several plant families with modern tropical affinities appeared. However, as in the Tiffanian, Clarkforkian floras had low diversity and were dominated by a single species in the birch family. Mean annual temperature (MAT) rose from an estimated 12 °C in the Tiffanian to 19 °C in the Clarkforkian, while mean annual precipitation (MAP) for the Tiffanian and Clarkforkian is estimated to have been 130-150 cm. Little fossil plant material is preserved from the latest Clarkforkian or the earliest Wasatchian, which is thought to have contained an interval of cooling and drying followed by renewed warming. By the middle Wasatchian, the time of the Cenozoic thermal maximum, the inferred MAT was about 21 °C, and the MAP was near 140 cm. A second influx of plant families with tropical affinities appeared in the area, and diversity increased significantly, but most plant families known from the Clarkforkian persisted. Species turnover from the Clarkforkian to the Wasatchian was greater than 80%. A second turnover of more than 80% of species (but not families) from the Wasatchian to the early Bridgerian accompanied drying and increased seasonality of precipitation. The early Bridgerian MAT is inferred to have been near 20 °C and the MAP to have been about 80 cm. Except for the Tiffanian and possibly portions of the early Wasatchian, paleoclimates during the study interval were predominantly frost free. Although the moderating influence of the Green River lake system has been suggested as a possible explanation for mild Eocene winters in Wyoming, this study shows that virtually frost-free climates existed in the area prior to and independent of significant lake development.
... The fruits are bi-winged nuts borne in globose to elongate-ellipsoidal cone-like infructescences. Infructescences with intact fruits are known from the Early Eocene of England (Reid & Chandler, 1933 as Petrophylloides;Manchester, 1987) and North Dakota (Wing & Hickey, 1984). The extinct fruit genera Hooleya from the Eocene of North America (Manchester, 1987;Wing & Hickey, 1984) and the Eocene to Oligocene of Europe (Reid & Chandler, 1926;Rasky, 1956) and Paleoplatycarya from Paleocene of North America show affinities with Platycarya (Wing & Hickey, 1984;Manchester, 1987). ...
... Infructescences with intact fruits are known from the Early Eocene of England (Reid & Chandler, 1933 as Petrophylloides;Manchester, 1987) and North Dakota (Wing & Hickey, 1984). The extinct fruit genera Hooleya from the Eocene of North America (Manchester, 1987;Wing & Hickey, 1984) and the Eocene to Oligocene of Europe (Reid & Chandler, 1926;Rasky, 1956) and Paleoplatycarya from Paleocene of North America show affinities with Platycarya (Wing & Hickey, 1984;Manchester, 1987). The triporate pollen of Platycarya has the usual diagnostic features of Juglandaceae (porate with ornamentation of evenly distributed scabrae) but is distinctive among other extant juglandaceous pollen by the presence of pseudocolpi, a pair of thin oblique troughs in the exine on both polar hemispheres. ...
... Infructescences with intact fruits are known from the Early Eocene of England (Reid & Chandler, 1933 as Petrophylloides;Manchester, 1987) and North Dakota (Wing & Hickey, 1984). The extinct fruit genera Hooleya from the Eocene of North America (Manchester, 1987;Wing & Hickey, 1984) and the Eocene to Oligocene of Europe (Reid & Chandler, 1926;Rasky, 1956) and Paleoplatycarya from Paleocene of North America show affinities with Platycarya (Wing & Hickey, 1984;Manchester, 1987). The triporate pollen of Platycarya has the usual diagnostic features of Juglandaceae (porate with ornamentation of evenly distributed scabrae) but is distinctive among other extant juglandaceous pollen by the presence of pseudocolpi, a pair of thin oblique troughs in the exine on both polar hemispheres. ...
We review the fossil history of seed plant genera that are now endemic to eastern Asia. Although the majority of eastern Asian endemic genera have no known fossil record at all, 54 genera, or about 9%, are reliably known from the fossil record. Most of these are woody (with two exceptions), and most are today either broadly East Asian, or more specifically confined to Sino-Japanese subcategory rather than being endemic to the Sino-Himalayan area. Of the “eastern Asian endemic” genera so far known from the fossil record, the majority formerly occurred in Europe and/or North America, indicating that eastern Asia served as a late Tertiary or Quaternary refugium for taxa. Hence, many of these genera may have originated in other parts of the Northern Hemisphere and expanded their ranges across continents and former sea barriers when tectonic and climatic conditions allowed, leading to their arrival in eastern Asia. Although clear evidence for paleoendemism is provided by the gymnosperms Amentotaxus, Cathaya, Cephalotaxus, Cunninghamia, Cryptomeria, Glyptostrobus, Ginkgo, Keteleeria, Metasequoia, Nothotsuga, Pseudolarix, Sciadopitys, and Taiwania, and the angiosperms Cercidiphyllum, Choerospondias, Corylopsis, Craigia, Cyclocarya, Davidia, Dipelta, Decaisnea, Diplopanax, Dipteronia, Emmenopterys, Eucommia, Euscaphis, Hemiptelea, Hovenia, Koelreuteria, Paulownia, Phellodendron, Platycarya, Pteroceltis, Rehderodendron, Sargentodoxa, Schizophragma, Sinomenium, Tapiscia, Tetracentron, Toricellia, Trapella, and Trochodendron, we cannot rule out the possibility that neoendemism plays an important role especially for herbaceous taxa in the present-day flora of Asia, particularly in the Sino-Himalayan region. In addition to reviewing paleobotanical occurrences from the literature, we document newly recognized fossil occurrences that expand the geographic and stratigraphic ranges previously known for Dipelta, Pteroceltis, and Toricellia.
... Hooleya has also been identified from the Eocene Clamo Formation of Oregon (Wing and Hickey 1984;Manchester 1987), where it occurs at the same localities as Palaeocarya and Cruciptera. Manchester and Dilcher (1982) suggested that Hooleya was most similar to Pterocarya in the Juglandeae tribe. ...
... Manchester and Dilcher (1982) suggested that Hooleya was most similar to Pterocarya in the Juglandeae tribe. Subsequently, Wing and Hickey (1984) and Manchester (1987) provided more convincing evidence for affinities within the tribe Platycaryeae. ...
... Although such recurved basilaminar extensions occur today only in the Engelardieae (in Oreomunnea mexicana [Standl.] Leroy), they also occur on leaflets of extinct Platycaryeae (Wing and Hickey 1984;Manchester 1987). The Messel leaflets correspond closely in petiole length, venation, and serration to those found in repeated association with Platycarya and Paleoplatycarya fruits from the early Eocene of North Dakota and Wyoming (Wing and Hickey 1984;Manchester 1987, pp. ...
The extinct genus Cruciptera, formerly documented only from the Tertiary of western North America, is recognized on the basis of well-preserved four-winged samaras, and a new species is described: Cruciptera schaarschmidtii. Analysis of the cuticle reveals peltate scales that complement morphological data in confirming the position of this genus in the Juglandaceae. The Messel fruits, together with two specimens from the middle Eocene pipe clays of southern England, indicate that Cruciptera was distributed in Europe as well as North America during the Eocene. A survey of juglandaceous fruits from the Eocene of Messel, Germany, reveals two additional genera: Palaeocarya and Hooleya. The tribal affinities of the Messel fruit genera are compared with those of juglandaceous foliage and pollen previously described from the same sediments. Palaeocarya and Hooleya share a similar paleogeographic distribution to that of Cruciptera, suggesting exchange via the Eocene North Atlantic land bridge.
... However, association with extinct platycaryoid fruit types such as Hooleya (Fig. 5 F) and Paleoplatycarya (Fig. 5 G) and with extinct platycaryoid foliage types suggests that very similar, possibly identical, pollen was produced by extinct genera of the Platycaryeae (MANCHESTER 1987). In examining pollen from the anthers of Platycarya americana catkins from the Early Eocene of North Dakota (Fig. 21, J), WING & HICKEY (1984) observed variation in pseudocoipi distribution and shape, from one to two per hemisphere and from straight to arcuate, circular, or Y-shaped. By implication, the various form species of Platycaryapollenites (KEDVES 1982 recognized eight species from the Paleocene of Menat, France) may represent variability within species rather than species diversity. ...
... Radiation of platycaryoid fruits. Unequivocal fruits of Piatycaryeae first occur in the earliest Eocene of Europe (REID & CHANDLER 1933) and North America (WING & HICKEY 1984), somewhat prior to the appearance of the first fruits of Engelhardieae, Fruits of Platycarya richardsoni (REID & CHANDLER) CHANDLER from the London Clay flora (Fig. 5 B) and Platycarya americana from the Golden Valley Formation of North Dakota, U.S.A. (Fig. 5 E) are virtually indistinguishable from those of the extant east Asian species P. strobilacea (Fig. 5 A, D), although the fruit wings are slightly larger. Foliage associated with Platycarya americana differs in many characters from that of the single extant species of Platycarya, and WING & HICKEY (1984) consider some of these to be simply more primitive features and some to be characters indicative of a close relationship to Engelhardieae. ...
... Foliage associated with Platycarya americana differs in many characters from that of the single extant species of Platycarya, and WING & HICKEY (1984) consider some of these to be simply more primitive features and some to be characters indicative of a close relationship to Engelhardieae. Extinct platycaryoid fruit morphotypes with large wings and prominent venation were also present during the Eocene, including Paleoplatycarya (Fig. 5 C, G) from the Lower Eocene of Wyoming (MANCHESTER 1987), Hooleya from the Eocene of Oregon (Fig. 5F) and Oligocene of England and Czechoslovakia (REID & CHANDLER 1926, WING & HICKEY 1984 indicate that the tribe was more diverse and widespread during the Early Tertiary than it is today. ...
The major radiation of theJuglandaceae occurred during the early Tertiary as recorded by the proliferation of juglandaceous pollen and the appearance of fruits representing extinct and extant genera of the family. Juglandaceous pollen types of the Paleocene were predominantly triporate and exhibited a greater diversity in patterns of exinous thinning than occurs in the family today. Analyses of in situ pollen from early Tertiary juglandaceous inflorescences confirms the taxonomic value of certain patterns of exinous thinning. Data from co-occurring fruits and pollen indicate that relatively unspecialized, isopolar triporate pollen of the type presently confined to the tribeEngelhardieae also occurred in other tribes of the family during the Paleocene. Pollination has been mostly anemophilous throughout the Tertiary. Both wind and animal fruit-dispersal syndromes were established early in the radiation of the family but a greater diversity of wind-dispersed genera has prevailed.
... The venation of these single specimens is preserved only as faint impressions in the matrix and photographs poorly; nevertheless, the marginal looping of the secondaries, the secondary veins that frequently branch before entering the teeth and the density of the venation, correspond to this genus. Despite the preservation, this fossil demonstrates the defining characteristics of Platycarya foliage (Wing and Hickey 1984). Foliage of this genus is very rare in the Greek Neogene, as it is only recorded in the Messinian-Tortonian localities of Samos (Velitzelos et al., 2014). ...
... Foliage of this genus is very rare in the Greek Neogene, as it is only recorded in the Messinian-Tortonian localities of Samos (Velitzelos et al., 2014). On the contrary, the genus is well documented on the basis of infructescences and fruits from the early Eocene of England (Reid and Chandler, 1933;Manchester, 1987a), North Dakota (Wing and Hickey, 1984), Wyoming (Dennison Cap; UF localities 18120, 18216) and from fruits first from the lower Oligocene of the Lyons and Bridge Creek floras of Oregon (Meyer and Manchester, 1997). This material indicates the first record of Platycarya sp. in the early Miocene deposits of Lesvos. ...
The pyroclastic rocks of the Lesvos Petrified Forest in the North Aegean comprise one of the early Miocene's most imposing megaflora assemblage. In this area, the new outcrop of Akrocheiras yielded numerous leaf compressions. Based on their macroscopic characteristics, we identified a total of sixteen different taxa, most of them of palaeotropical origin. Dominant species are Daphnogene polymorpha, Pungiphyllum cruciatum and Phoenicites sp., represented by more than 50% of the specimens. Several taxa are new for the Neogene palaeobotanical record of Lesvos Island, such as Smilax weberi, Celtis japeti, Apocynophyllum sp., Laurophyllum sp. 1, cf. Ilex sp., Ilex miodipyrena and div. Juglandaceae and provide new floristic data for the area. According to the vegetation analysis, the plant assemblage of Akrocheiras site assigned to lowland/ riparian and mesophytic forests on well drained soils. The palaeoclimatic analysis for the new flora revealeda humid warm-temperate climate with seasonal alternations from wetter to drier conditions. The floristic characteristics are outlined, and the record is compared to other records of the early Miocene period.
... Juglandaceae have an extensive fossil record in the Northern Hemisphere that includes fruits, flowers, pollen, leaves, and wood of both extant and extinct genera. We selected five fossil fruit taxa and their associated floral and vegetative organs for inclusion in the analysis (see Figs. 1, 2): Polyptera manningii Dilcher, 1982, 1997), Paleooreomunnea stoneana (Dilcher et al., 1976), Cruciptera simsonii (Manchester, 1991), Paleoplatycarya wingii (Manchester, 1987), and Platycarya americana (Wing and Hickey, 1984). These fossils were selected based on the relatively complete morphological data sets that could be compiled for them from wellpreserved and thoroughly investigated suites of specimens. ...
... Juglandaceae have been the subject of several morphological analyses derived from the distinct perspectives of researchers working with fossil and modern taxa (e.g., Wing and Hickey, 1984;Manchester, 1987;Manos and Stone, 2001). Although a moderately sized morphological data set was available for modern taxa and thought to be exhaustive (50 characters; Manos and Stone, 2001), this study shows that a paleobotanical perspective can provide additional characters (14 characters) and critical reinterpretations of several previously studied characters that had been evaluated only among extant diversity (see Appendix 2, online). ...
It is widely acknowledged that integrating fossils into data sets of extant taxa is imperative for proper placement of fossils, resolution of relationships, and a better understanding of character evolution. The importance of this process has been further magnified because of the crucial role of fossils in dating divergence times. Outstanding issues remain, including appropriate methods to place fossils in phylogenetic trees, the importance of molecules versus morphology in these analyses, as well as the impact of potentially large amounts of missing data for fossil taxa. In this study we used the angiosperm clade Juglandaceae as a model for investigating methods of integrating fossils into a phylogenetic framework of extant taxa. The clade has a rich fossil record relative to low extant diversity, as well as a robust molecular phylogeny and morphological database for extant taxa. After combining fossil organ genera into composite and terminal taxa, our objectives were to (1) compare multiple methods for the integration of the fossils and extant taxa (including total evidence, molecular scaffolds, and molecular matrix representation with parsimony [MRP]); (2) explore the impact of missing data (incomplete taxa and characters) and the evidence for placing fossils on the topology; (3) simulate the phylogenetic effect of missing data by creating "artificial fossils"; and (4) place fossils and compare the impact of single and multiple fossil constraints in estimating the age of clades. Despite large and variable amounts of missing data, each of the methods provided reasonable placement of both fossils and simulated "artificial fossils" in the phylogeny previously inferred only from extant taxa. Our results clearly show that the amount of missing data in any given taxon is not by itself an operational guideline for excluding fossils from analysis. Three fossil taxa (Cruciptera simsonii, Paleoplatycarya wingii, and Platycarya americana) were placed within crown clades containing living taxa for which relationships previously had been suggested based on morphology, whereas Polyptera manningii, a mosaic taxon with equivocal affinities, was placed firmly as sister to two modern crown clades. The position of Paleooreomunnea stoneana was ambiguous with total evidence but conclusive with DNA scaffolds and MRP. There was less disturbance of relationships among extant taxa using a total evidence approach, and the DNA scaffold approach did not provide improved resolution or internal support for clades compared to total evidence, whereas weighted MRP retained comparable levels of support but lost crown clade resolution. Multiple internal minimum age constraints generally provided reasonable age estimates, but the use of single constraints provided by extinct genera tended to underestimate clade ages.
... Sparganium globites, Cupressacites hiatipites), and palynotaxa with relatives living in tropical or dry tropical climates decline to a minimum for the time interval under study here. The low abundance of Platycarya in palynofloras and megafloras during this time, its higher abundance in Wyoming later in the Ypresian during the Early Eocene Climatic Optimum (Wing, 1984), and its abundance in Gulf Coastal Plain palynofloras (Wing & Hickey, 1984), may indicate it preferred warm, wet climates. A cooler and wetter climate during the post-PETM early Ypresian has also been inferred from other proxies including megafloral composition, leaf physiognomy, oxygen isotope composition of hematite nodules, and the common occurrence of tabular carbonaceous shale beds in the central BHB (Bao et al., 1999;Wing, 1984;Wing & Currano, 2013;Wing & Harrington, 2001;Wing et al., 2005Wing et al., , 2009). ...
To better understand the effect of the Paleocene‐Eocene Thermal Maximum (PETM) on continental ecosystems, we studied 40 new palynological samples from the Bighorn Basin (BHB), northwestern Wyoming, USA. We see palm and fern abundances increase in the last 20–40 ka of the Paleocene, then dramatically with the onset of the carbon isotope excursion (CIE) defining the base of the PETM. Palynomorphs of plant groups with modern temperate climate distributions are absent from the CIE body, and this is when tropical plants are most diverse and abundant. During the CIE recovery, pollen of mesophytic/wetland plants become more common while tropical taxa persist. In the post‐CIE early Eocene tropical taxa are rare and temperate forms abundant, similar to the late but not latest Paleocene. Changes in the palynoflora are more easily detected if reworked palynomorphs are removed from analyses. We interpret palynofloral changes to indicate warming in the latest Paleocene, rapid warming and drying with the CIE onset, dry tropical climates through the CIE body, a return to wetter floodplains during a very warm CIE recovery, and cooler wet conditions in the post‐PETM early Eocene. These inferences are consistent with geochemical and paleobotanical proxies. Strikingly similar patterns in the palynoflora and megaflora suggest changes in vegetation were a basin‐wide phenomenon. These rapid, climatically forced changes in floral composition occurred without major extinction, perhaps indicating nearby refugia in which plants adapted to cooler and wetter climates persisted through the PETM.
... They are again accompanied by typical leaves and isolated leaflets at Kučlín (Engelhardia orsbergensis), inferred to belong to the same plant as in many other sites (e.g., Holý Kluk, Suletice-Berand). (Wing and Hickey 1984) was described from the Early Oligocene to latest Eocene Bembridge Marl (Reid and Chandler 1926), Socka (Unger 1850b) and from other localities of the European Eocene (e.g., Eckfeld -Frankenhäuser and Wilde 1994, Messel -Manchester et al. 1994, rarely in Early Oligocene (Manchester 1987a). Although the whole plant is not known, typical slender, fine toothed leaflets and complete leaves accompany these juglandaceous fruits at Eckfeld (Wilde and Frankenhäuser 1998). ...
... Family remarks. Species of the Juglandaceae are successful in a warm temperate to subtropical North America, as records of both extinct and extant genera clearly demonstrate (Wing and Hickey, 1984;Manchester, 1991;Manchester and Dilcher 1997;Manos and Stone, 2001;Elliott et al., 2006;). Carya first appears in Eocene sediments in North America (Manchester, 1999). ...
The late Pliocene was an important time of relatively recent global warmth, and it heralded the end of Neogene Epoch. However, plant fossils from this time are uncommon in North America. This study provides detailed descriptions of 23 plant fossil taxa representing 14 woody angiosperm families from the late Pliocene (mid-Piacenzian) Citronelle Formation in coastal Alabama. This is the only significant late Pliocene megafossil plant assemblage in eastern North America, and one of the few from the entire Neogene of this region. Many are first records of their kind, and several are confidently identified to the species level. Overall, the floral composition is similar to that of the modern Gulf Coast. These findings, along with previous records, form the basis of quantitative paleoclimate estimates using leaf margin analysis (LMA), the Coexistence Approach (CoA), the Bioclimatic Analysis/Mutual Climate Range Technique (BA/MCRT), and the climate leaf multivariate program (CLAMP). The CLAMP analysis had the highest site-to-site disparity and provided anomalously low mean annual temperature (MAT) and mean annual precipitation (MAP) values. The LMA, CoA analysis, and BA/MCRT results are likely better proxies in this case, as the climate estimates obtained are closer to independent proxies and modern values. The BA/MCRT MAT results were most convincing at 18ºC. Nevertheless, higher MAT results were expected, as the mid-Piacenzian was a time of global warmth. Precipitation estimates below modern values obtained in all the relevant analyses are consistent with the presence of white pine in the Citronelle flora.
... Early Eocene megafossils of Platycarya (P. castaneopsis and P. americana) are thought to have been early successional plants based on their small, wind-dispersed seeds, pinnately compound leaves, and the growth habit and habitats of their living congener (Wing and Hickey 1984). Living (and presumably fossil) Platycarya are also deciduous. ...
During the first 10-20 Kyr of the Eocene temperatures warmed by 4-8°C in middle and high latitudes, then cooled again over the succeeding ∼200 Kyr. Major changes in the composition of marine and terrestrial faunas, including one of the largest mammalian turnover events of the Cenozoic, occurred during this temperature excursion. To better understand the effects of rapid climatic change on continental biotas, we studied 60 fossil pollen samples collected from 900 m of section spanning approximately three million years of the late Paleocene and early Eocene; the samples come from the Fort Union Formation and Willwood Formation in the Bighorn Basin of northwestern Wyoming, paleolatitude approximately 47°N. There are 40 samples from the 500 m of rock deposited during the one million year interval centered on the Paleocene/Eocene boundary, although pollen was not preserved well in rocks representing the short warm interval at the base of the Eocene. Overall, the palynoflora shows moderate change in composition and diversity. Two pollen taxa clearly expanded their ranges to include North America in the first 400 Kyr of the Eocene, Platycarya (Juglandaceae), and Intratriporopollenites instructus (cf. Tilia), but they account for less than 5% of pollen grains in the early Eocene. There are no last appearances of common taxa associated with the Paleocene/Eocene boundary. The most noticeable palynological changes are the decrease in abundance of Caryapollenites spp. and Polyatriopollenites vermontensis (Juglandaceae), and the increase in abundance of Taxodiaceae (bald cypress family), Ulmaceae (elm family), and Betulaceae (birch family), particularly Alnipollenites spp. (alder). There are 22% more species in the Eocene samples than in the Paleocene samples; mean richness of Eocene samples is 17% higher than the mean of Paleocene samples. The mean evenness of Eocene samples is higher than that of Paleocene samples, but the difference is not significant. The modest level of floral change during the late Paleocene and early Eocene contrasts with the major taxonomic turnover and ecological rearrangement of North American mammalian faunas observed at the same time. Faunal change probably resulted from intercontinental range expansion across Arctic land bridges that became habitable as a result of high-latitude warming, so it is surprising that climatically sensitive plants did not also experience a major episode of interchange. The absence of fossil plants from the temperature excursion interval itself could prevent us from recognizing a transient shift in floral composition, but it is clear that the flora did not undergo a major and permanent restructuring like that seen in the mammals. The contrast between the moderate floral response to warming and the strong faunal response is consistent with the idea that interactions between immigrant and native taxa, rather than climate directly, were the primary cause of terrestrial biotic change across the Paleocene/Eocene boundary.
... When anatomical and epidermal features are not preserved, fossil angiosperm leaves are most often reliably assigned using attachments, which are rare (Crane and Stockey, 1985;Manchester et al., 1986;Boucher et al., 2003;Zamaloa et al., 2006), or repeated co-occurrence (Wing and Hickey, 1984;Manchester and Hickey, 2007) with other organs considered diagnostic, most often fl owers, fruits, and seeds. This approach attains high botanical precision but usually for a small minority of the leaf species inferred to be present. ...
Abstract—The great bulk of the angiosperm fossil record consists of isolated fossil leaves that preserve abundant
shape and venation (leaf architectural) information but are diffi cult to identify because they are not attached
to other plant organs. Thus, poor taxonomic knowledge has tempered the tremendous potential of fossil leaves
for constructing fi nely resolved records of biodiversity through time, extinction and recovery, past climate
change and biotic response, paleoecology, and plant-animal associations. Moreover, paleoecological and paleoclimatic
interpretations of fossil leaves are in great need of new approaches. Recent work is rapidly increasing
the scientifi c value of fossil angiosperm leaves through advances in traditional paleobotanical reconstruction,
phylogenetic understanding of both leaf architecture and the response of leaf shape to climate, quantitative plant
ecology using measurable, correlatable leaf traits, and improved understanding of insect leaf-feeding damage.
These emerging areas offer many novel opportunities to link paleoecology and neoecology. Increased collaboration
across traditionally separate research areas is critical to continued success.
... (both Juglandaceae, relatives of the hickory and walnut), Laevigatosporites haardtii (a primary colonist fern), Alnipollenites verus, A. trina (both Betulaceae, relatives of alders) and Platycaryapollenites platycaryoides (another hickory relative), form an association characteristic of mid succession wetland communities (cf. Wing & Hickey 1984). More stable, mature areas marginal to Figure 8 Polarity information for the Faroe Islands Basalt Group of the Faroe Islands. ...
The Palaeogene volcanic succession of the Faroe Islands in the NE Atlantic Ocean is formalised using a purely lithostratigraphic approach and following international guidelines. The Faroe Islands Basalt Group (FIBG) has a gross stratigraphic thickness of 6·6 km, dominated by subaerial basalt lava flows, and is subdivided into seven formations. The Lopra Formation forms the basal 1·1 km of the Lopra-1/1A borehole, dominated by hyaloclastites, volcaniclastic sandstones and invasive basaltic lavas/sills. It is overlain by the 3·25 km-thick Beinisvørð Formation, dominated by laterally extensive basalt sheet lobes separated by minor volcaniclastic lithologies. The Beinisvørð Formation is overlain by the <15 m-thick, inter-eruption, coal-bearing facies of the Prestfjall Formation and the <50 m-thick, syn-eruption, pyroclastic and sedimentary facies of the Hvannhagi Formation. Lava flow volcanic activity resumed with the <1·4 km-thick Malinstindur Formation, dominated by thinly bedded compound basalt lava flows. The top of this formation is marked by a regional disconformity surface, overlain by sandstone and conglomerate deposits of the maximum 30 m-thick Sneis Formation, a newly recognised stratigraphic unit. The final phase of volcanism recorded on the Faroe Islands consists of the >900 m-thick Enni Formation composed of a mixture of basalt sheet lobes and compound flows with abundant volcaniclastic units, e.g. the Argir Beds, that may require a further subdivision at this stratigraphic level. The new lithostratigraphy allows for more refined biostratigraphical and sequence stratigraphic correlations and prepares for a revised geological map of the Faroe Islands.
... Remarks. The infructescence is of a general juglandaceous aspect and resembles Platycarya americana from the Lower Eocene of North Dakota (Wing & Hickey, 1984), but details of the nutlet morphology are scarcely discernible. ...
The mid-Cenomanian fish beds of Nammoura, Mont-Liban district, Lebanon contain a diverse fauna of aquatic and terrestrial vertebrates, a few crustaceans and moderately well-preserved plant remains of which a single species,Sapindopsis anhouryi , was previously described by Dilcher & Basson (1990). We add 11 species of ferns, gymnosperms and angiosperms of which Nammouria cretacea gen. et sp. nov, Nupharanthus cretacea gen. et sp. nov., Sapindopsis libanensis sp. nov. and Nammourophyllum altingioides gen. et sp. nov. are new taxa. The florule differs markedly from both Early Cretaceous and Turonian plant assemblages of the Middle East, thereby representing a distinct stage of the regional floristic evolution. Its phytogeographic affinities are with contemporaneous floras of North America, Central Europe and the Crimea. A combination of such features as xeromorphism, the prevalence of compound leaves, and the presence of deciduous angiosperm components and gymnosperms may indicate climatic conditions similar to those of the present day Mediterranean.
Platycarya strobilacea belongs to the walnut family (Juglandaceae), is commonly known as species endemic to East Asia, and is an ecologically important, wind pollinated, woody deciduous tree. To facilitate this ancient tree for the ecological value and conservation of this ancient tree, we report a new high-quality genome assembly of P. strobilacea. The genome size was 677.30 Mb, with a scaffold N50 size of 45,791,698 bp, and 98.43% of the assembly was anchored to 15 chromosomes. We annotated 32,246 protein-coding genes in the genome, of which 96.30% were functionally annotated in six databases. This new high-quality assembly of P. strobilacea provide valuable resource for the phylogenetic and evolutionary analysis of the walnut family and angiosperm.
The Paleogene lava flows of the Faroe Islands Basalt Group are divided into three relatively thick formations. The oldest, the Beinisvørð Formation is separated from the second lava flow succession, the Malinstindur Formation, by two formations composed primarily of volcaniclastic rocks. The oldest of these, the Prestfjall Formation has been interpreted as a period of eruptive quiescence and linked to changes in mantle melting. It is characterised in the south by the occurrence of coals, while the overlying Hvannhagi Formation is a sequence of primary and remobilised volcaniclastic strata. Field, laboratory, palynology, and photogrammetry studies have been used to investigate variations in facies and architecture within these volcaniclastic formations. The data reveal significantly different depositional systems in the Prestfjall and Hvannhagi formations over the ~40 km from the island of Vágar in the north to the island of Suðuroy in the south. Facies distribution in both the Prestfjall and Hvannhagi formations was found to have been controlled by a complex interaction of regional paleoslope, pre-existing topography, the eruption and local collapse of low-angle shield volcanoes, and minor brittle deformation. Lithological data and photogrammetry have enabled the identification of a > 180 m thick succession of volcaniclastic conglomerates deposited by lahars reworking a low-angle shield sector collapse. Co-occurrence of facies characteristic of the Prestfjall, Hvannhagi and Malinstindur formations indicate that volcanic eruption continued at a lower tempo throughout the Prestfjall Formation interval. Identification of a Beinisvørð Formation low-angle volcano shield northwest of the Faroe Islands alters the previous eruption model for this extensive lava field.
Leaves are the most abundant and visible plant organ, both in the modern world and the fossil record. Identifying foliage to the correct plant family based on leaf architecture is a fundamental botanical skill that is also critical for isolated fossil leaves, which often, especially in the Cenozoic, represent extinct genera and species from extant families. Resources focused on leaf identification are remarkably scarce; however, the situation has improved due to the recent proliferation of digitized herbarium material, live-plant identification applications, and online collections of cleared and fossil leaf images. Nevertheless, the need remains for a specialized image dataset for comparative leaf architecture. We address this gap by assembling an open-access database of 30,252 images of vouchered leaf specimens vetted to family level, primarily of angiosperms, including 26,176 images of cleared and x-rayed leaves representing 354 families and 4,076 of fossil leaves from 48 families. The images maintain original resolution, have user-friendly filenames, and are vetted using APG and modern paleobotanical standards. The cleared and x-rayed leaves include the Jack A. Wolfe and Leo J. Hickey contributions to the National Cleared Leaf Collection and a collection of high-resolution scanned x-ray negatives, housed in the Division of Paleobotany, Department of Paleobiology, Smithsonian National Museum of Natural History, Washington D.C.; and the Daniel I. Axelrod Cleared Leaf Collection, housed at the University of California Museum of Paleontology, Berkeley. The fossil images include a sampling of Late Cretaceous to Eocene paleobotanical sites from the Western Hemisphere held at numerous institutions, especially from Florissant Fossil Beds National Monument (late Eocene, Colorado), as well as several other localities from the Late Cretaceous to Eocene of the Western USA and the early Paleogene of Colombia and southern Argentina. The dataset facilitates new research and education opportunities in paleobotany, comparative leaf architecture, systematics, and machine learning.
Keywords
Angiosperms, cleared leaves, data science, fossil leaves, leaf architecture, paleobotany
Background: The walnut family (Juglandaceae) contains commercially important woody trees commonly called walnut, wingnut, pecan and hickory. Phylogenetic relationships in the Juglandaceae are problematic, and their historical diversification has not been clarified, in part because of low phylogenetic resolution and/or insufficient marker variability.
Results: We reconstructed the backbone phylogenetic relationships of Juglandaceae using organelle and nuclear genome data from 27 species. The divergence time of Juglandaceae was estimated to be 78.7 Mya. The major lineages diversified in warm and dry habitats during the mid-Paleocene and early Eocene. The plastid, mitochondrial, and nuclear phylogenetic analyses all revealed three subfamilies, i.e., Juglandoideae, Engelhardioideae, Rhoipteleoideae. Five genera of Juglandoideae were strongly supported. Juglandaceae were estimated to have originated during the late Cretaceous, while Juglandoideae were estimated to have originated during the Paleocene, with evidence for rapid diversification events during several glacial and geological periods. The phylogenetic analyses of organelle sequences and nuclear genome yielded highly supported incongruence positions for J. cinerea, J. hopeiensis, and Platycarya strobilacea. Winged fruit were the ancestral condition in the Juglandoideae, but adaptation to novel regeneration regimes after the Creaceous-Paleogene boundary led to the independent evolution of zoochory among several genera of the Juglandaceae.
Conclusions: A fully resolved, strongly supported, time-calibrated phylogenetic tree of Juglandaceae can provide an important framework for studying classification, diversification, biogeography, and comparative genomics of plant lineages.
New fossils provide the earliest unequivocal evidence of grasses. Spikelets and inflorescence fragments with included pollen from the Paleocene/Eocene Wilcox Formation in western Tennessee have a suite of diagnostic characters that limits their affinities to Poaceae. Associated vegetative remains are also suggestive of grasses, but are not well enough preserved for an unequivocal identification. These fossils indicate a minimal time of origin for the family, are consistent with an Upper Cretaceous origin of Poaceae, and suggest that as in wind-pollinated Hamamelididae, wind pollination evolved in grasses or persisted in the grass lineage (if a wind-pollinated grass sister group is presumed) in dry tropical environments.
"New fossil provide the earliest unequivocal evidence of grasses..."
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American Journal of Botany 78 (7) :1010-1014
The phylogenetic relationships of the genera of the Juglandaceae are examined with cladistic analyses of chloroplast DNA (cpDNA) restriction site variation and morphology. Rates of evolution of the chloroplast genome are slower than in many other groups of plants, enabling the entire genome to be utilized at the intergeneric level. The trees resulting from the two independent analyses were completely congruent. The combined analysis of the two data sets produced a tree completely congruent with the cladogram from the two data sets analyzed independently. The cladogram is compared with previous classifications, cladistic analyses, and fossil history for the family. Although the topology resulting from the cladistic analyses of this study was strongly congruent with previous estimates of relationships within the family, the fossil record indicates that the basal-most lineages in the cladistic trees arose later than the more terminal lineages. This reversed order of origin indicates that perhaps the rooting of the trees is erroneous.
The first combined petrographic and geochemical investigation of coal from the Faroe Islands was performed as a case study to understand thermal effects from basaltic lava flows on immature coal. The samples were divided into two distinct groups: “normal” coal (xylite and detroxylite) and “altered organic matter” (charcoal and organic particles dispersed in samples rich in altered clastic mineral components or enriched via hydrothermal fluids). The “normal” coal consists primarily of huminite-group material dominated by ulminite. The proportions of material from inertinite and liptinite groups vary from sample to sample. The studied macerals are anisotropic with no observed reaction rims or vacuoles. According to the mean ulminite reflectance in combination with ultimate and proximate analyses, the coal reached the lignite and subbituminous stages. The maceral compositions together with coal palynology indicate a predominance of gelified wood-derived tissues and demonstrate that the coal evolved in wet forest swamps under limno-telmatic to telmatic conditions.
Palynological assemblages recovered from horizons within the late Palaeocene Reading Beds of north Essex contain an unusual Pteridopyte spore-dominated microflora. These assemblages are dominated by Camerozonosporites heskemensis (Pflanzl in Murriger & Pflanzl) Krutzsch 1959 and Leiotriletes maxoides Krutzsch 1962 and are lacking in significant numbers of angiosperm and gymnosperm pollen. It is suggested that this microflora was derived from a fern-dominated primary colonising community exploiting an unstable floodplain environment. The Pteridopyte-dominated community is contrasted with the angiospermdominated communities identified in south Essex, London and the North Sea Basin.
Comparisons of Tertiary floras of North America with those of Europe and Asia document a long history of floristic interchange. The stratigraphic and geographic ranges of selected conifer and angiosperm genera that are easily recognized in the fossil record provide a basis for discerning patterns in the routes and timings of intercontinental dispersals through the Tertiary.
Abstract The monotypic genus Platycarya (Juglandaceae) is one of the most widespread temperate tree species in East Asia. In this research, we implemented a phylogeographical study using chloroplast DNA (cpDNA) (psbA‐trnH and atpB‐rbcL intergenic spacer) sequences on Platycarya strobilacea, in order to identify the locations of the species’ main refugia and migration routes. A total of 180 individuals of P. stobilacea from 27 populations from China and Jeju Island (Korea) were collected. The results revealed that P. strobilacea had 35 haplotypes for the two intergenic spacers and high genetic diversity (h T= 0.926). This surprisingly high diversity of haplotypes indicates its long evolutionary history, which is in agreement with previous phylogenetic analyses and fossil records. Significant cpDNA population subdivision was detected (G ST= 0.720; N ST= 0.862), suggesting low levels of recurrent gene flow through seeds among populations and significant phylogeographical structure (N ST > G ST, P Document Type: Research Article DOI: http://dx.doi.org/10.1111/j.1759-6831.2012.00210.x Affiliations: , Publication date: July 1, 2012 $(document).ready(function() { var shortdescription = $(".originaldescription").text().replace(/\\&/g, '&').replace(/\\, '<').replace(/\\>/g, '>').replace(/\\t/g, ' ').replace(/\\n/g, ''); if (shortdescription.length > 350){ shortdescription = "" + shortdescription.substring(0,250) + "... more"; } $(".descriptionitem").prepend(shortdescription); $(".shortdescription a").click(function() { $(".shortdescription").hide(); $(".originaldescription").slideDown(); return false; }); }); Related content In this: publication By this: publisher By this author: CHEN, Shi‐Chao ; ZHANG, Li ; ZENG, Jie ; SHI, Fei ; YANG, Hong ; MAO, Yun‐Rui ; FU, Cheng‐Xin GA_googleFillSlot("Horizontal_banner_bottom");
Platycarya strobilacea Siebold & Zucc. is a monotypic genus and an unusual and rare tree in cultivation. Its discovery and introduction into cultivation are described.
The biogeographic affinities of the Cretaceous and early Tertiary angiosperm floras of the North American area (which includes Meso-America, and the Greater Antilles) have been the subject of considerable interest. Although recent treatments of isolated taxa have shown affinities between North American, European, east Asian and Neotropic floras, the relationships have not been quantified. This study compiles the records of fossils whose familial relationships seem secure. This provides a carefully culled, and uniformly presented review of the Cretaceous and Paleogene record from 1950 to 1989 and supplements LaMotte (1950). A subset of these records, which showed compelling evidence of subfamilial relationships, was analyzed to quantify the relationships of the Cretaceous, Paleocene, Eocene and Oligocene floras to other regions. The analysis suggests that for the entire period 24% of the fossil species had affinities with extant taxa from the Northern Hemisphere; 10% with taxa from the Northern Hemisphere that have a few species in South America; 17% with taxa from Eurasia; 3% with taxa with a disjunct Eurasian-South American pattern; 19% with taxa from South America and/or Africa; 8% with taxa from South America and/or Africa that have an important sister group in southeast Asia; 5% with taxa from the Old World; and 13% with taxa having other distribution patterns. Those fossils with affinities to Laurasian taxa are mostly found in the northern and western portions of the North American area. The fossils with affinities to South American and/or African taxa are found in the southern portions of North America, Meso-America, and the Greater Antilles. The taxa with disjunct distributions show both patterns. These patterns suggest that during this time there were wide-spread temperate elements, found throughout Laurasia; Boreotropical flora elements, distributed in North America, Europe and along the Tethys seaway to southeast Asia; and West Gondwana elements which show dispersion from South America across the proto-Caribbean. The paleobotanical data are compatible with current geological, paleontological and biogeographical studies.
Synopsis
BGS borehole 77/7, located to the north of Scotland, drilled through Quaternary deposits into Neogene and Palaeogene sediments before terminating in Lewisian basement. The pre-Quaternary rocks have been analysed using a variety of petrological, geochemical and bio-stratigraphical techniques. The basement comprises amphibolite schist, and has a deeply weathered surface which, it is argued, is likely to have developed during the early Eocene. Overlying terrestrial lignitic deposits are palynologically dated as upper Oligocene; they were deposited in a forest swamp environment at a time of hinterland uplift, and are comparable with sediments of similar age and character found in basins along the length of western Britain. Following a rise in sea level, marine conditions prevailed during the Miocene, as recorded by glauconitic siltstones which are of a facies that is extensively developed on the outer shelf and slope NW of Scotland.
Jones. J.H., Manchester, S.R and Dllcher, D.L., 1988. Dryophyllum Debey ex Saporta, juglandaceous not fagaceous. Rev. Palaeobot. Palynol., 56: 205-211. Type specimens of Dryophyllum subcreta.ceum Debey ex Saporta 1868 from the Paleocene of France, representing the type species of Dryophyllum, have been reexamined. Although Dryophyllum has long been used for fossil leaves of supposed fagaceous affinities, the leaf architecture observed in the type specimens of D. subcretaceum indicates affinitles with the JugLandaceae and excludes it from the Fagaceae. The diagnoses of the genus and type species have therefore been emended. As revised, the name Dryophylll11n may be used for fossil leaflets with architecture similar to that of extant Pterocarya, Juglans, Cyclocarya. and Ca.rya.
Palaeogene volcanism on the NW margin of the Faroe-Shetland Basin is represented by the Faroes Lava Group, within an age range of 57.5–60.56 Ma. The volcanic sequence comprises >1000 m of basaltic volcaniclastic rocks deposited in estuarine or marginal lagoons, overlain by three laterally-extensive formations of subaerial facies basaltic lavas: Lower, c. 3250 m; Middle, c. 1400 m; Upper, at least 900 m (top not preserved). The Lower and Upper formations comprise high-volume sheet flows, commonly with ferrallitized tops, interbedded with reddened, thin, fluvial claystone and basaltic siltstone deposits. Laterally-impersistent coals occur within the Lower Lava Formation. The Coal-bearing Formation (c. 20 m) was deposited in an overbank floodplain environment during an hiatus in the volcanism between the Lower and Middle formations. The Volcaniclastic Sandstone Sequence comprises hydroclastic and pyroclastic deposits which post-date the Coal-bearing Formation and represent a return to volcanism, prior to the eruption of the Middle Lava Formation which is mainly characterized by inflated pahoehoe flows. The onshore sequence of the Faroes Lava Group can be correlated with basaltic flows within the Faroe-Shetland Basin, where lavas in Well 205/9-1 are interpreted to be of Lower Lava Formation affinity, possibly erupted from a local vent system. Seismic and gravity mapping and modelling suggest that the offshore extension of the Lower Lava Formation, together with the oldest part of the Middle Lava Formation, comprise subaqueous hyaloclastites deposited in a prograding Gilbert-type lava delta system. The youngest part of the Middle Lava Formation and all of the Upper Lava Formation occur as subaerial facies lavas within the basin.
Palaeogene sedimentary strata from beneath the basaltic lavas of East Greenland have yielded a suite of palynofloras which determine the age and environment of deposition of these rock units. These palynofloras include Apectodinium augustum, Deflandrea oebisfeldensis and a pollen assemblage containing common Caryapollenites veripites with Camerozonospotites heskemensis and Stereisporites in assemblages characteristic of the latest Paleocene to earliest Eocene Sequence T40. This allows a correlation to be established, complementing an already established framework based on lava geochemistry, which shows that lava eruption in East Greenland was initiated somewhat later than in the Faroe Islands. It also highlights the presence of a widespread major unconformity in the East Greenland succession, spanning the late Maastrichtian to the end of the Paleocene. The lack of sedimentation throughout the Early Paleocene, and majority of the Late Paleocene, highlights the possibility of Paleocene sedimentary systems bypassing the East Greenland shelf, with clastic deposition forced eastwards towards the area of the Faroe Islands and the More and Voring basins.
A variety of nut-producing plants have mutualistic seed-dispersal interactions with animals (rodents and corvids) that scatter
hoard their nuts in the soil. The goals of this review are to summarize the widespread horticultural, botanical, and ecological
literature pertaining to nut dispersal inJuglans, Carya, Quercus, Fagus, Castanae, Castanopsis, Lithocarpus, Corylus, Aesculus, andPrunus; to examine the evolutionary histories of these mutualistic interactions; and to identify the traits of nut-bearing plants
and nut-dispersing rodents and jays that influence the success of the mutualism. These interactions appear to have originated
as early as the Paleocene, about 60 million years ago. Most nuts appear to have evolved from ancestors with wind-dispersed
seeds, but the ancestral form of dispersal in almonds (Prunus spp.) was by frugivorous animals that ingested fruit.
Nut-producing species have evolved a number of traits that facilitate nut dispersal by certain rodents and corvids while serving
to exclude other animals that act as parasites of the mutualism. Nuts are nutritious food sources, often with high levels
of lipids or proteins and a caloric value ranging from 5.7 to 153.5 kJ per propagule, 10–1000 times greater than most wind-dispersed
seeds. These traits make nuts highly attractive food items for dispersers and nut predators. The course of nut development
tends to reduce losses of nuts to insects, microbes, and nondispersing animals, but despite these measures predispersal and
postdispersal nut mortality is generally high. Chemical defenses (e.g., tannins) in the cotyledons or the husk surrounding
the nut discourage some nut predators. Masting of nuts (periodic, synchronous production of large nut crops) appears to reduce
losses to insects and to increase the number of nuts dispersed by animals, and it may increase cross-pollination. Scatter
hoarding by rodents and corvids removes nuts from other sources of nut predation, moves nuts away from source trees where
density-dependent mortality is high (sometimes to habitats or microhabitats that favor seedling establishment), and buries
nuts in the soil (which reduces rates of predation and helps to maintain nut viability). The large nutrient reserves of nuts
not only attract animal dispersers but also permit seedlings to establish a large photosynthetic surface or extensive root
system, making them especially competitive in low-light environments (e.g., deciduous forest) and semi-arid environments (e.g.,
dry mountains, Mediterranean climates). The most important postestablishment causes of seedling failure are drought, insufficient
light, browsing by vertebrate herbivores, and competition with forbs and grasses. Because of the nutritional qualities of
nuts and the synchronous production of large nut crops by a species throughout a region, nut trees can have pervasive impacts
on other members of ecological communities. Nut-bearing trees have undergone dramatic changes in distribution during the last
16,000 years, following the glacial retreat from northern North America and Europe, and the current dispersers of nuts (i.e.,
squirrels, jays, and their relatives) appear to have been responsible for these movements.
Paleobotanical studies indicate that several isolated and systematically depauperate groups of extant woody dicotyledons originated in the Mid Cretaceous. TheChloranthaceae had probably differentiated into insect-pollinated (Chloranthus andSarcandra) and wind-pollinated (Ascarina andHedyosmum) forms by the end of the Albian, and leaves referable to theTrochodendrales are known from the Albian and Cenomanian. In the latest Cretaceous and Early Tertiary, extinct representatives of theTrochodendrales includedNordenskioldia and theJoffrea-Nyssidium complex. ThePlatanaceae also differentiated before the end of the Albian and initially had insect-pollinated, unisexual flowers with five carpels or stamens. Some of these features persisted in the platanoid lineage until the Early Tertiary, and during the Paleocene and Eocene thePlatanaceae included forms with elliptical, palmate and pinnate foliage. The history of thePlatanaceae suggests that several features of the reproductive morphology of extant taxa may have arisen in association with a trend toward wind pollination. In the Mid Cretaceous, platanoid foliage partially intergrades with pinnateSapindopsis and pedateDebeya-Dewalquea leaves suggesting a close relationship betweenPlatanaceae andRosidae andFagaceae respectively. TheChloranthaceae, Trochodendrales, andPlatanaceae all occupy a somewhat intermediate position between theMagnoliidae andHamamelidae and are of considerable interest with respect to their role in the initial radiation of nonmagnoliid (higher) dicotyledons.
Although temporal calibration is widely recognized as critical for obtaining accurate divergence-time estimates using molecular dating methods, few studies have evaluated the variation resulting from different calibration strategies. Depending on the information available, researchers have often used primary calibrations from the fossil record or secondary calibrations from previous molecular dating studies. In analyses of flowering plants, primary calibration data can be obtained from macro- and mesofossils (e.g., leaves, flowers, and fruits) or microfossils (e.g., pollen). Fossil data can vary substantially in accuracy and precision, presenting a difficult choice when selecting appropriate calibrations. Here, we test the impact of eight plausible calibration scenarios for Nothofagus (Nothofagaceae, Fagales), a plant genus with a particularly rich and well-studied fossil record. To do so, we reviewed the phylogenetic placement and geochronology of 38 fossil taxa of Nothofagus and other Fagales, and we identified minimum age constraints for up to 18 nodes of the phylogeny of Fagales. Molecular dating analyses were conducted for each scenario using maximum likelihood (RAxML + r8s) and Bayesian (BEAST) approaches on sequence data from six regions of the chloroplast and nuclear genomes. Using either ingroup or outgroup constraints, or both, led to similar age estimates, except near strongly influential calibration nodes. Using "early but risky" fossil constraints in addition to "safe but late" constraints, or using assumptions of vicariance instead of fossil constraints, led to older age estimates. In contrast, using secondary calibration points yielded drastically younger age estimates. This empirical study highlights the critical influence of calibration on molecular dating analyses. Even in a best-case situation, with many thoroughly vetted fossils available, substantial uncertainties can remain in the estimates of divergence times. For example, our estimates for the crown group age of Nothofagus varied from 13 to 113 Ma across our full range of calibration scenarios. We suggest that increased background research should be made at all stages of the calibration process to reduce errors wherever possible, from verifying the geochronological data on the fossils to critical reassessment of their phylogenetic position.
Fossil pollen grains from Paleocene-Eocene rocks of the Bighorn Basin of Wyoming allow important sequences of terrestrial
vertebrate fossils to be correlated with standard marine microfossil zonations. The Paleocene/Eocene boundary as based on
pollen evidence falls within the Wasatchian land mammal age, much higher than the boundary used by some fossil mammal workers.
This discrepancy partly results from multiple definitions of the Paleocene/Eocene boundary but may also indicate faulty mammal-based
correlations to the type Sparnacian of France.
The fluvial lower Eocene Willwood Formation (Bighorn Basin, Wyoming) is composed largely of red, oxidized, overbank sediment that has been extensively altered by soil formation. Within this matrix are two different types of dominantly fine grained, drab- to dark-colored deposits that contain abundant plant remains. Interpretations stress the interaction of vegetational succession, soil characteristics, and fluvial morphology in creating the chemical conditions that led to the preservation of organic matter. The stratigraphic distribution of the two types of deposits within the Willwood Formation suggests that in the Bighorn Basin, tectonism exerted a greater influence on the geometry of carbonaceous deposits than did climate.-Author
A new genus of juglandaceous winged fruit, is described from the Reading Beds (Upper Palaeocene) of southern England. It comprises one of the earlier macrofossil records of the Juglandaceae, and is the earliest from the European Tertiary. The fruit represents an extinct genus related to the extant tribe Engelhardieae, but excluded from it by its simple unlobed bract. Cladistic analysis shows Casholdia to display generalized engelhardioid fruit morphology. It lacks the tri-lobed bract diagnostic of the Engelhardieae, and predates the first occurrence of such bracts in the fossil record. Casholdia adds to the mounting evidence indicating an early Palaeogene radiation of the Juglandaceae.
Magnetostratigraphic correlation of the Eureka Sound Formation in the Canadian high Arctic reveals profound difference between the time of appearance of fossil land plants and vertebrates in the Arctic and in mid-northern latitudes. Latest Cretaceous plant fossils in the Arctic predate mid-latitude occurrences by as much as 18 million years, while typical Eocene vertebrate fossils appear some 2 to 4 million years early.
The winged fruits of Engelhardia have been reported in many early Tertiary floras in the northern Hemisphere. Recent systematic revisions of the extant genera, Engelhardia, Oreomunnea, and Alfaroa provide a helpful guide to the study of the fossil fruits. Fruit form, venation, nut septations and flower parts are features that separate the extant Asian Engelhardia from the American Oreomunnea. Four types of fossil winged fruits can be recognized in Middle Eocene sediments of southeastern North America: Engelhardia, Paraoreomunnea gen. n., Paleooreomunnea gen. n., and Pararengelhardia. Both Paleooreomunnea and Paraengelhardia represent extinct lines; no living forms have similar winged fruits. The fossil fruits of Engelhardia and Paraoreomunnea are similar to the fruits of extant Engelhardia and Oreomunnea, respectively. The fossil taxa reported in this paper were sympatric. The present allopatric distribution of Engelhardia and Oreomunnea is the result of Neogene regional extinctions. Engelhardia and Oreomunnea have probably been distinct genera since early Paleogene time.
Alfaroa mexicana is described as new. Certain aspects of the wood anatomy, inflorescence, pollen, staminate flower, and pistillate flower morphology are compared with previous findings on the three other species of Alfaroa and representatives of the closely related genus Engelhardia.
A classification of the architectural features of dicot leaves—i.e., the placement and form of those elements constituting the outward expression of leaf structure, including shape, marginal configuration, venation, and gland position—has been developed as the result of an extensive survey of both living and fossil leaves. This system partially incorporates modifications of two earlier classifications: that of Turrill for leaf shape and that of Von Ettingshausen for venation pattern. After categorization of such features as shape of the whole leaf and of the apex and base, leaves are separated into a number of classes depending on the course of their principal venation. Identification of order of venation, which is fundamental to the application of the classification, is determined by size of a vein at its point of origin and to a lesser extent by its behavior in relation to that of other orders. The classification concludes by describing features of the areoles, i.e., the smallest areas of leaf tissue surrounded by veins which form a contiguous field over most of the leaf. Because most taxa of dicots possess consistent patterns of leaf architecture, this rigorous method of describing the features of leaves is of immediate usefulness in both modern and fossil taxonomic studies. In addition, as a result of this method, it is anticipated that leaves will play an increasingly important part in phylogenetic and ecological studies.
Palynologie data have been obtained from 30 localities in the Swauk, Naches, and Roslyn Formations of central Washington and in the Puget Group of western Washington. Although the Swauk Formation previously has been assigned ages as old as Paleocene or Cretaceous, palynologie results show that the type Swauk Formation is Eocene and that the Swauk Formation of the Chiwaukum graben and Wenatchee areas is Eocene and Oligocene. Correlations based on palynomorph biozones show that the Swauk, Naches, Teanaway, and Roslyn Formations of central Washington are time-equivalent to the Puget Group of western Washington and are part of the same depositional sequences of Eocene and Oligocene age. Palynomorph biozones found useful in this study include the Pistillipollenites and Platycarya concurrentrange zone, early(?) and middle Eocene; the Platycarya and Bursera concurrent-range zone, late Eocene; and the Gothanipollis and Elaeagnus concurrent-range zone, Oligocene. These concurrent-range zones can be used to correlate the central Washington formations and Puget Group with other strata in southwestern Washington and in the Bellingham, Washington, and Vancouver, British Columbia, areas.
Morphological and anatomical evidence is presented for recognizing the generic status of the two American species of Juglandaceae with winged fruits. Oreomunnea pterocarpa is endemic to Costa Rica, while O. mexicana ranges from Mexico to Costa Rica. Engelhardia nicaraguensis Molina is reduced to synonymy under O. mexicana subsp. mexicana, and O. mexicana subsp. costaricensis is described as new. Information is provided on the geographic range, general ecology, morphology, and taxonomy of the American taxa. The somatic count of 2n = 32 for O. mexicana subsp. mexicana is the first report for the genus.
Coherent patterns of morphology of apparent value in determining taxonomic and phylogenetic relationships are present in dicotyledonous leaves. Features of greatest value in assessing these affinities include leaf organization; marginal features, including morphology of the tooth; major vein configuration; characters of the intercostal venation; and gland placement. Of these, recognition of tooth morphology appears to be an overlooked tool of major systematic importance. Variation in these features is most coherent when analyzed in terms of the Takhtajan and Cronquist systems of dicot classification. Essential to our procedure was a recognition of the "basic" leaf features of each taxon. These were regarded as the most generalized type from which all of the more specialized types in a taxon could have been derived and they were derived from an analysis of the comparative morphology of modern leaves with limited input from the fossil record. The resulting scheme indicates strong correlation of leaf features with six of the seven Takhtajan subclasses, in addition to paralleling and clarifying both systems at the ordinal and familial levels. Conspicuous exceptions are the breakdown of the Asteridae into a possible rosid and a possible dilleniid group, reassignment of the Celastrales and Myrtales to the Dilleniidae, and of the Juglandales to the Rosidae. Affinities of numerous problem taxa, such as the Didymelaceae and Medusagynaceae, are resolved, as are some of the points of disagreement between the Takhtajan and Cronquist arrangements. This analysis also provides the first systematic summary of dicot leaf architectural features and the outlines of a regular systematic method for leaf determination.
A B S T R A C T A classification of the architectural features of dicot leaves-i.e., the placement and form of those elements constituting the outward expression of leaf structure, including shape, marginal configuration, venation, and gland position-has been developed as the result of an extensive survey of both living and fossil leaves. This system partially incorporates modifications of two earlier classifications: that of Turrill for leaf shape and that of Von Ettingshausen for venation pattern. After categorization of such features as shape of the whole leaf and of the apex and base, leaves are separated into a number of classes depending on the course of their principal venation. Identification of order of venation, which is fundamental to the application of the classification, is determined by size of a vein at its point of origin and to a lesser extent by its behavior in relation to that of other orders. The classification concludes by describing features of the areoles, i.e., the smallest areas of leaf tissue surrounded by veins which form a contiguous field over most of the leaf. Because most taxa of dicots possess consistent patterns of leaf architecture, this rigorous method of describing the features of leaves is of immediate usefulness in both modern and fossil taxonomic studies. In addition, as a result of this method, it is anticipated that leaves will play an increasingly important part in phylogenetic and ecological studies.
Sequential morphologic changes in pollen of the Momipites‐Caryapollenites lineage from Paleocene strata in the Wind River Basin of Wyoming appear to reflect evolution within the family Juglandaceae. The stratigraphic occurrence of the species within this complex permits the establishment of six biostratigraphic zones that can be correlated between outcropping and subsurface sequences within the basin and to surrounding areas.Trends involving changes in shape and size of the pollen and in structure of exine at the poles proceed from a basic form of Momipites to six other distinguishable species. The genus Caryapollenites appears to have been derived from the basic form of Momipites by changes in size and development of heteropolarity in pore position.Species of Momipites described as new are M. wyomingensis, M. waltmanensis, M. ventifluminis, M. actinus, M. anellus, and M, leffingwellii. The genus Caryapollenites is redescribed and C. prodromus, C. imparalis, C. inelegans, and C. wodehousei are described as new.
This paper discusses the morphology, taxonomy, and stratigraphic occurrences of 62 forms of spores and pollen grains and four forms of freshwater(?) microplankton, in the Paleogene part of the Oak Grove core from northeastern Virginia. The known geologic ranges of these taxa in southeastern United States are also given. Seven new species are proposed: Lusatisporis indistincta, Momipites flexus, Nuxpollenites psilatus, Piolencipollis endocuspoides, Porocolpopollenites virginiensis, Triatriopollenites triangulus, and Tricolpites crassus.Sporomorph occurrences in seven samples from the upper Sabinian (lower Eocene) and lower Claibornian (lower part of the middle Eocene) of the Gulf Coast are also listed; these samples were analyzed to provide additional control for correlating the assemblages from Virginia with those in southeastern United States. Several sporomorph taxa, including Carya and Kyandopollenites anneratus, appear to range lower in the section (into probable Midwayan rocks) in Virginia than they do farther to the south.On the basis of sporomorphs and other fossils, the Oak Grove core includes the following sequence in ascending order: Aquia(?) Formation, probably Midwayan (lower Paleocene), 12.5 m thick; Aquia Formation, lower Sabinian (upper Paleocene), 22.3 m thick; Marlboro Clay, lower Sabinian, perhaps the upper part of the formation being upper Sabinian (lower Eocene), 5.4 m thick; and Nanjemoy Formation, upper Sabinian, 37.4 m thick. The position of the boundary between the lower and upper Sabinian (that is, the Paleocene‐Eocene boundary) could not be precisely determined by means of sporomorphs because of a lack of data on sporomorph assemblages from near this boundary in southeastern United States. The sequence in the Oak Grove core appears to represent more or less continuous deposition across the boundary between the lower and upper Sabinian; such a sequence rarely if ever occurs in southeastern United States.
Twenty pollen species recovered from auger samples of an isolated pod of sediment within the Piedmont Province of Meriwether County, Georgia, indicate a late Paleocene (early Sabinian) age for the deposit. The age assignment is based on the concurrent ranges of the species as they occur in the Gulf and Atlantic Coastal Plains. No dinoflagellate cysts or acritarchs were observed in the samples examined, and their absence supports stratigraphic and sedimentologic evidence for a nonmarine origin of the sediments. The sediments have been protected from erosion by faulting along the southern margin of the basin containing them. The structural relationships and the Paleocene age for the deposit provide evidence of Cenozoic tectonic activity within the Piedmont Province of Georgia. Regional stratigraphic and sedimentologic evidence suggests that the deposit was probably a northward extension of the bauxite districts of Andersonville, Georgia, and Eufaula, Alabama.Illustrations of the twenty biostratigraphically important pollen types are presented, as are illustrations of other angiosperm pollen from the deposit.
This paper presents the observed stratigraphic ranges of 99 sporomorph (spore and pollen) taxa in the lower Paleocene to upper Oligocene part of the core from the U.S. Geological Survey Clubhouse Crossroads corehole 1 near Charleston, South Carolina. Morphologic and taxonomic data are given for some of these taxa, and three new species are proposed: Nyssapollenites paleocenicus, Osculapollis? colporatus, and Triporopollenites microgranulatus.Fifty‐four sporomorph taxa in the core samples also are found in significant numbers in Gulf Coast Paleogene deposits. The Gulf Coast Paleogene section is divided into 18 provisional sporomorph assemblage zones by using occurrence data from the literature on these 54 taxa. Each South Carolina sample is compared numerically with each Gulf Coast assemblage zone, producing a binary SCMC (presence‐absence Similarity Coefficient Matrix Contour) diagram. Use of this method indicates that sporomorph correlation of “packages”; of Paleogene strata is generally feasible between South Carolina and the Gulf Coast with the data now available. Sporomorph correlations are also possible using a binary Shaw diagram and a ranked relative‐frequency SCMC diagram, but neither of these two methods suggests such detailed correlations as the binary SCMC diagram.
Juglandaceous pollen of the Early Tertiary deposits of North America and Europe exhibit basic morphology like that of modern species of the family and some features not found in modern species. Pollen morphology suggests several phyletic trends within the family in Early Tertiary time. Morphogenetic trends among triporate species of the Juglandaceae, especially of the Engelhardia‐Alfaroa group, involve thinning, thickening, and folding of exine at the poles, or inflation of the atria. Morphologic evidence indicates close phyletic relationship between Engelhardia and Carya. Morphologic groups are defined among fossil triporate juglandaceous species, and relationships are suggested.Momipites Wodehouse 1933 is emended, and Engelhardtiapollenites Raatz 1937, Engelhardtioidites Potonie’, Thomson, and Thiergart 1950, Engelhardtioipollenites Potonié 1951, and Maceopolipollenites Leffingwell 1971 are submerged in it. Momipites triradiatus and M. wodehousei are described as new, and 17 new combinations are proposed.
The sporopollinic association in the uppermost Sparnacian facies of the “Montagne de Reims” is made of varioustaxons, which are typical of warm and moist climates.Some of these taxons belong to the littoral or mangrove flora; they need saline water. Others come from freshwater environments, swamp-forest and even from the inner land.Although the analized samples were picked up in the uppermost layers of the Sparnacian facies, some speciesof pollen and microplankton are of Cuisian affinity.
This paper discusses the morphology, taxonomy, and stratigraphic occurrences of 24 species and species groups of triatriate pollen. The material is from uppermost Paleogene rocks of the U. S. Geological Survey Charleston Project Deep Corehole No. 1 (Clubhouse Crossroads corehole), Dorchester County, South Carolina. The 24 pollen types are assigned to seven genera: Momipites, Plicatopollis, Platycaryapollenites, Platycarya, Subtriporopollenites, Carya, and Casuarinidites. The definitions of the first three of these genera are emended in this paper, and five new species are proposed: Momipites fragilis, Momipites strictus, Momipites? annulatus, Plicatopollis cretacea, and Casuarinidites sparsus.The stratigraphically lowest occurrence of juglandaceous triatriate pollen in the core is in rocks of Austinian (possible Santonian) Age, and altogether seven triatriate types are known from the Upper Cretaceous. The maximum diversity of these pollen types is in the upper Paleocene and lower Eocene (13–15 forms per stratigraphic level).Eleven apparently significant pollen‐stratigraphie events have been determined on the basis of first, last, and peak occurrences of triatriate pollen in the Austinian‐Chickasawhayan interval of the core.
At Verzenay, in the Reims area, the upper part of the “Lignites du Soissonnais” have been turned into a paleosol. A petrographical and geochimical study of this profile allow us to see there a fossilized mangrove soil.A palynological study carried out on the same samples shows typical taxons of the mangrove environment (Nypa, Bruguiera, Acrostichum aureum). Then, palynological results perfectly agree with the sedimentological interpretation.
A diverse assemblage of 80 species of fossil spores and pollen was recovered from the Tertiary section of the COST No. B‐2 well, Baltimore Canyon, Atlantic Outer Continental Shelf. Many of the species have stratigraphic ranges with well‐defined tops and are therefore potentially useful as age indicators for the Tertiary strata of the Atlantic OCS. The previously reported occurrence of sediments of Paleocene age is questionable because the highest occurrence of pollen similar to that of modern Platycarya, generally regarded as Eocene age indicators, is the same interval.
The diversity of fruit types within the Amentiferae appears to be the result of different seed dispersal and seedling establishment
strategies that have evolved independently in the amentiferous families within the confines imposed by the wind-pollination
syndrome. Dispersal of unadorned fruits and seeds by wind (e.g.,Betula, Rhoiptelea, Casuarina) has preceded the development of more efficient air-borne devices (e.g.,Ostrya, Carpinus, Engelhardia). Animal dispersal is the most advanced strategy, relying rarely on drupes, as in the shrubby Myricaceae, or on nuts, as
inCorylus, Quercus, Carya, Juglans, Alfaroa, etc. The pattern of seedling establishment shows a structural-functional relationship to the seeddispersal strategy. Epigeal
germination predominates in plants of open habitats. Those species with small fruits rely on wind dispersal, and their seeds
have a relatively short germination time, whereas species with medium-sized fruits are often animal-dispersed with seeds that
may have protracted germination times. In either case the reserve food supply for the young seedling is limited, and light
is needed to spark photosynthesis. Hypogeal germination has evolved independently in several amentiferous families (e.g.,
Betulaceae, Fagaceae, Juglandaceae). This pattern is associated with closed habitats and plants with large seeds that have
the capability of establishing vigorous seedlings in microhabitats of reduced light intensity where photosynthesis is impaired.
The subterranean protection afforded the cotyledons and axillary meristems is a correlative feature that may have considerable
importance in seedling survival where desiccation and predation are intense.
The Orinoco Delta in eastern Venezuela is an excellent modern analog for Upper Carboniferous depositional environments in terms of climate, physiography, sedimentology, and the presence of morphological analogs for Upper Carboniferous plants. Processes resulting in the incorporation of plant parts in sediment were studied to assess the effects of transport and deposition on plant parts preserved as compressions in clastic strata of Late Carboniferous age. Sub-environments of the delta (e.g. levee, point bar, clastic swamp, and distributary channel) were cored and the contained plant matter described in terms of its distribution in sediment, preservational state, and relationship to living vegetation. Several experiments were performed to assess the role of tidal and fluvial transport of plants parts. We reached the following conclusions from the study: (1) Aerial parts of plants are buried relatively close to their site of growth but rarely in the actual soils in which the plants lived. (2) Plant parts are preferentially preserved in areas with slightly higher rates of sedimentation. (3) Natural levees are dry for half a year and any aerial parts of plants buried in levee deposits during floodstage oxidize during that time. Bioturbation by roots also contributes to the destruction of plant matter. Thus, levee sediments are virtually devoid of aerial parts of plants. (4) Tidal processes are as significant as annual flooding in forming plant-bearing deposits in the lower delta plain. (5) No storm-generated deposits are known in the Orinoco Delta, indicating that non-storm deposition is important for the generation of clastic deposits which contain plant parts.
Thesis (Ph.D.)--University of British Columbia.
Thesis (M.A. in Paleontology)--University of California, Berkeley, June 1959. Includes bibliographical references (leaves 80-84). Microfilm. s
Thesis (Ph. D.)--Pennsylvania State University. Microfilm (positive).
1840 History of the fossil fruits and seeds of the
- B Owerbank
The significance of wood anatomy in the taxonomy of the Juglandaceae
- Heimsch
Eocene plants from Wyoming
- Berry E. W.
The recognizable species of the Green River flora
- Brown R. W.
- Chandler
The Noroshi flora of Noto Peninsula, central Japan. Memoirs Faculty Sci., Kyoto Univ., Ser
- Ishida S.
Paleocene and Eocene age of the Coalmont Formation, North Park, Colorado
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