ABSTRACTS SUBMITTED TO THE 23RD ANNUAL MIDCONTINENT PALEOBOTANICAL COLLOQUIUM
John C. Benedict1, Kathleen B. Pigg1 and Melanie L. DeVore2
1Arizona State University, Tempe
2Georgia College & State University, Milledgeville
Three incomplete triloculate fruits with axile placentation have been discovered at the Late Paleocene "Kate’s Butte" site of Beicegel Creek, in McKenzie County, western North Dakota, USA. This locality has a flora very similar to the well known Almont locality in central North Dakota, but is preserved in a more chertified matrix that, unlike the Almont flora, can be studied with the cellulose acetate peel technique, as well as by surface fractures. The fruits are 6-8 mm in diameter, loculicidally dehiscent, and have a well developed exo- and endocarp. The exocarp is comprised of aerenchymatous cells and the endocarp of tightly arranged parenchymatous tissue. Vascular bundles occur at the periphery of the fruit wall, alternating in position with the dehiscence slits. Three major bundles occur in the central fruit axis. Associated with the fruits are seeds with a thick, spirally striate seed coat that conform to the genus Spirematospermum Chandler. These seeds often contain structures previously referred to as "clavate structures" by Crane, et al. in their 1990 survey of the Almont flora. The clavate structures are also found isolated in the matrix. Both those that are isolated and those within seeds represent monocot embryos with similarities to several types of extant zingiberalean seeds. Together the fruits, seeds, embryos and associated leaf remains may represent the various organs of the Spirematospermum plant.
Sergio Bravi1, Maria Rosaria Barone Lumaga2, and James E. Mickle3
1Dipartimento di Scienze della Terra Università "Federico II", Largo San Marcellino 10, 80138 Napoli, Italy
2Orto Botanico, Università "Federico II" Via Foria 223, 80139 Napoli, Italy
3Department of Botany, Box 7612, North Carolina State University, Raleigh, N.C. 27695- 7612 U.S.A.
A single specimen of a new angiosperm has been recovered from fine-grained limestones of the "plattenkalk" of the Middle Albian at Monte Alburni near Petina, province of Salerno, regione of Campania, Italy. Associated fossil plants include Pagiophyllum sp. , Podozamites sp. and Zamites sp. The angiosperm specimen consists of a main axis with one attached leaf and a distal cyme bearing three fructifications. The specimen is approximately 8 cm long, with the main axis about 1.75 mm wide and remaining at a relatively uniform width. At the proximal end of the specimen there are three lateral appendages displaying an apparently alternate arrangement. About 4 cm from the base of the specimen and lying underneath the main axis there is a lobed structure, presumably a leaf. About 0.5 cm from the insertion of a lateral appendix axillary to which are two small leaves, probably still in early states of development; of these one is lobate and about 2 mm long. In proximity to the specimen, part of a lobed leaf is visible. The petiole is not in direct connection with the main axis; however, from the position of the petiole and form of the leaf, it is highly probable that it comes from the same plant as the axis. The leaf has a petiole that is 4 mm long and about 0.5 mm wide; the leaf shows an obtuse base, on the right side of the lamina three lobes with deep crescents are visible. Lobes are about 2 mm deep and 1.5 mm wide. Primary venation is elongate; it is not possible to discern secondary venation. This leaf is similar in morphology to Vitiphyllum. At the distal end of the axis a dichasium subtended by a 5 mm long axillary bract bears three fructifications. One fructification is borne singly on what appears to be a continuation of the main axis, the other two are borne on a branching lateral axis, giving a cymose appearance to the specimen. The first fructification, born singly, is approximately 1.1 cm long, and 0.6 cm wide. This fructification is borne on a peduncle 1 cm long and 1 mm wide that supports one receptacle with three visible follicles that show a maximum width of 3 mm and partially fused in their basal two-thirds. At a distance of approximately 1.5 mm from the receptacle two linear structures approximately 2.5 mm long are interpreted as bract-like leaves. The fruiting structure born singly was cracked in the course of collection, which exposed internal structures. In the proximal portion of the fruiting structure, two series of two – three rounded cavities approximately 0.5 mm in diameter are visible, presumably showing the previous positions of seeds. The other two fructifications show only the outer surfaces, are of similar size and display divided distal tip indicating three, perhaps four divisions. Affinities of the specimen are not clear but show similarities in overall morphology to Ranunculaceae.
Cevallos-Ferriz, S.R.S1., Laura Calvillo Canadell1 and Enrique González Torres2
1Departamento de Paleontología, Instituto de Geología, UNAM,
Ciudad Univesitaria, Del Coyoacan, 04510 Mexico D.F.
2Departamento de Geología Regional, Instituto de Geología, UNAM,
Ciudad Univesitaria, Del Coyoacan, 04510 Mexico D.F.
The joint discussion of biotic and abiotic factors allows the proposal of hypothesis in which the dynamic nature of the geological processes impacting on the continental relief and climate, as well as on the organisms, facilitating the understanding of biodiversity. In this respect, we highlight that since the Cretaceous Mexico had a configuration similar to that of a peninsula that increased in size with time, and changed upon the establishment of the Isthmus of Panama approximately 3.5 my ago; that having this peninsular configuration the main mountainous belts formed in different episodes of time, achieving variable height and width through dynamic and fluctuant processes until reaching their extant physiognomy; that the retreat of the seas was significant so that upon the exposition of positive zones of the continent life became established; and, that the peninsula of Baja California and the Yucatan peninsula upon occupying their positions provided cover to the central continental mass of Mexico. The fossil record suggests that as all this occurred, the generated environments were occupied by plants that formed part of higher latitude communities of North America; that through the land bridges that connected North America with Europe and Asia plants with different geographical affinities arrived to Mexico; and that upon the establishment of the flora of Mexico in the Chortis Block, at least part of the plants growing in the region arrived to Central America and expanded their distribution to South America. The interaction of the biological processes with a variable environment gave place to the development and establishment of a distinctive biota, among which the endemic plants standout, since they characterize today to the vegetation of Mexico. History of lineages can be traced back to the Oligocene and possibly since at least the Eocene; but the current landscape and the elements that form part of it began their "modernization" some 3.5 million years ago, although they may have a long history.
Judy Iju Chen and Steve R. Manchester
Florida Museum of Natural History
Four vitaceous seeds have been reported from Eocene of Parina sandstone, Peru. An extant seed survey of Vitaceae has been conducted and the re-examination of these fossil seeds confirmed the identification of Ampelocissus bravoi by Berry. The specimen of Cissus willardi Berry was not observed, however the line drawing of the specimen shows resemblance to extant Cissus. Carpolithus cissiformis Berry does not resemble any extant seeds of Vitaceae examined. Carpolithus olssoni Berry shows clear resemblance to extant Leea seed. Seeds of Leea are characterized by having a pair of linear ventral infolds very closely spaced, a linear vascular strand (a ridge) wrapping around the dorsal side, and a simple to complex lateral rumination. Fruits of Leea are mostly 6-seeded so the seeds are compressed laterally and shaped like 1/6 of a ball. Some fruits are 9-seeded and the seeds would be more compressed. Carpolithus olssoni is preserved as the internal cast of the endosperm, it shows all the characters of a Leea seed with simple lateral rumination. The fossil seed is highly compressed, implying a fruit more than 6-seeded. Extant Leea has 34 species, mostly distributed on SE Asia and Melasia. The two most widespread species L. gueensis and L. indica extend to Africa, and one(two?) species endemic in Madagascar. Seed survey of Leea shows the species with complex lateral rumination occurs only in Philippine, New Guinea, and Madagascar but never on SE Asia. Species with simple rumination occur on SE Asia, Melasia and Africa. The fossil from Peru confirm its occurrence on S America at Eocene. This is the first reported fossil seed of Leea.
Walton A. Green
Department of Geology, Yale University, New Haven, Connecticut, 06520, USA
The leaf morphologies found in a flora can be indicative of the environmental conditions in which the flora grew. Given a sample of modern floras for training purposes, regression models allow estimation of past environmental variables like temperature. When sampling is irregular, however, regression statistics are sensitive to autocorrelation, so collecting more data points does not necessarily improve the estimate of temperature, even when it reduces the standard error of the estimate. For instance, if two climate stations close to each other record the same mean annual temperature and have similar floras, then an additional data point located between them is also likely to be similar. If this intermediate point is included in the training data set, it may alter the fitted regression line and increase its apparent accuracy, even though no additional information has been considered. This procedure can in theory be continued indefinitely and the regression line determined entirely by the effect of irregular sampling. In order to avoid this sort of bias, we would like to sample uniformly so as to have an even grid of floras distributed across the region of interest. In practice, this would be prohibitively time-consuming for any non-trivial grid size. As has been pointed out, however, the existence of reasonably accurate range maps for a large number of species, makes it possible to synthesize an arbitrary number of floras on a regular grid. Using the range maps for North American tree species drawn by Elbert Little in the 1960s and 70s, I show how this approach produces believable synthetic floras on a 1/2-degree grid, and how this approach can be used to unpack the environmental information encoded in leaf morphology.
of Nature & Science
The Middle Eocene Parachute Creek Member of the Green River Formation is widely exposed in the Piceance Creek and Uinta Basins of northwestern Colorado and northeastern Utah and is world famous for spectacular fossil plants and insects. These 46-47 million year old fossils have been collected for over 100 years and are much younger and considerably different from the fossils from the fish-bearing Green River Formation from Fossil Lake near Kemmerer, Wyoming. Parachute Creek sites primarily produce fossil plants and insects but fish, birds, lizards, and other vertebrates are occasionally recovered. The flora and fauna from this unit enjoy huge popular interest and the collecting sites near Bonanza, Utah and Douglas Pass, Colorado are internationally known.
In 1991, The Denver Museum of Nature & Science (DMNS) began work at these sites with the guidance and help of B. Handley, S. Manchester, and H. and D. Emry and it rapidly became apparent that there were many more species than the 69 described by MacGinitie (1969). The Bureau of Land Management (BLM), the agency responsible for managing the fossil-rich federal land near Bonanza and Douglas Pass; the Western Interior Paleontology Society (WIPS); and DMNS formed a partnership in which WIPS fieldtrips excavated Green River fossils from Douglas Pass with common fossils going to the finder and rare fossils being transferred to DMNS.
In 1996, DMNS excavated and censused a quarry near Bonanza. The resulting collection of 989 identifiable specimens represents 48 species. The most common genera were Parvileguminophyllum (27%), Cedrelospermum (25%), Macginitiea (8%), Rhus (7%), Allophylus (6%), Caesalpina (4%), and Cardiospermum (4%). Based on other fieldwork and donations from private collectors, DMNS has now accumulated a large collection of Parachute Creek fossil plants representing more than 250 morphotypes from over 50 individual quarries.
Due to the popularity of the Bonanza and Douglas Pass sites, we perceived a need and a demand for a digital atlas of the flora. Such an atlas would be useful for amateur collectors because it would allow them to identify their fossils. It would be useful for land managers because it would help them to define the scientifically significant and rare fossils. Scientists would benefit by having a more educated collecting public who could in turn recognize rare specimens and donate them to research museums. PaleoCollaborator software developed by S. Wagner allowed for the launch of the GRPP website in mid-2004. The website (http://greenriver.dmns.org/) provides a method for these species to be available on the web for comparison and identification. The site also functions as a living prodromous of the flora with new taxa being added as they are submitted by the collecting public and approved by the team.
Alex Kittle1, Melanie DeVore1 and Kathleen Pigg2
1Georgia College & State University, GA 31061
2Arizona State University, Tempe, AZ 85287.
During the 2005 field season, a new compression flora stratigraphically up section from the Paleocene Beicegel Creek siliceous shale floras was surveyed. This flora includes well articulated branches of Zizyphoides and Nordenskioldia and fruits and leaves of a cercidiphyllaceous plant. Leaf types assignable to Aesculus and platanceous leaves and fruits are also present. This compression flora occurs in association with a molluscan assemblage that allows for assignment to a middle Tiffanian (Ti3 or Ti4) age. Associated units below have yielded fragments of Plastomenus (soft-shelled turtle) and a single crocodilian tooth. The depositional environment is interpreted as an oxbow lake-type environment on a floodplain based on the fine grain size, high fossil content, the presence of lignite and lignitic clays, and the thick channel sands. The new compression locality will provide some significant clues regarding plant assemblages in a lower energy environment vs. plant assemblages found in the Beicegel Creek siliceous unit representing a higher energy environment.
Stefan A. Little, Selena Y. Smith, and Ruth A. Stockey
Dept. of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2E9, CAN
The autofluorescent properties of extant and ancient plant remains are well documented. In particular, cuticles and pollen have been viewed under excitation filters to aid in visualizing specimens. Recent investigations of permineralized plants from several localities in western Canada (Apple Bay, Cretaceous; Appian Way, Eocene; Princeton Chert, Eocene), using the cellulose acetate peel technique, have shown that peels mounted onto glass microscope slides are prime candidates for study using Confocal Laser Scanning Microscopy (CLSM). A Leica TCS-SP2 spectral confocal and multiphoton system, was used to view various specimens, including fruits, seeds, pollen and vegetative organs. Pyrite, if present, autofluoresced very strongly, as well as cuticle, pollen walls and oil idioblast contents. Finer scale resolution of CLSM improves observation of small details compared to similar observations using excitation filters with typical light microscopy. In addition, sequential scans can be used as image stacks in the AMIRA 3.1.1 software to produce three-dimensional reconstructions. Developmental hypotheses, based on anatomy, are tested by noting the presence of cuticle and sporopollenin in sequences of maturing fruits and anthers, respectively. Comparing abundance of autofluorescence for similar remains across all three localities correlates with quality of preservation at these sites, improving our understanding of preservation at these sites.
Tony Matthews1, Melanie DeVore and Kathleen Pigg2
1Georgia College & State University, Milledgeville, GA 31061
2Arizona State University, Tempe, AZ 85287
Filicalean Ferns and fern allies are a common component of Tertiary floras, but are often neglected. One of the more perplexing aspects of the Paleocene Almont Flora was the absence of ferns. However, when equivalently aged and similarly preserved floras were found in the badlands of North Dakota, ferns and Isoetes were represented. Unlike the Almont flora, material from the Beicegel Creek tends to have a greater percentage of permineralized specimens and provides an unparalleled opportunity to critically examine both the anatomy and morphology of taxa. One of the fern taxa identified from Beicegel Creek is Woodwardia (similar to W. aerolata), an important component of the circumboreal flora of the Northern Hemisphere Paleocene. At least two additional ferns occur within permineralized blocks as anatomically preserved rhizomes ( 3 x 8 mm across) with simple solenosteles with narrow C-shaped stipe traces. Fragmentary remains of pinnules and associated indusia and sori are also present. Individual sporangia have a prominent annuls and some contain spores. In 2005, Isoetes megasporophylls containing several hundred spiny megaspores were recovered. New occurrences of ferns and fern allies from the Beicegel Creek flora, even of fragmentary remains, can increase out knowledge of filicalean fern evolution and diversification in the Tertiary.
Ian M. Miller and Walton A. Green
Department of Geology and Geophysics
Yale University, 210 Whitney Ave. New Haven, CT 06511
Elevation and latitude correlate, at first order, to atmospheric parameters like moisture and temperature. An obvious modern example of this relationship between leaf morphology and environment is the tree line, where boreal forests give way to artic (high latitude) or alpine (high elevation) tundra. Several quantitative methods, all of which rely on uniformitarianism, have been developed to estimate paleoelevation using fossil leaf morphology. These include 1) the univariate leaf-margin analysis (LMA), which estimates mean annual temperature (MAT) by the positive correlation between MAT and P, the proportion of entire or smooth to non-entire or toothed margined woody dicotyledonous angiosperm leaves within a flora and 2) the Climate Leaf Analysis Multivariate Program (CLAMP) which uses Canonical Correspondence Analysis (CCA) to estimate MAT, moist enthalpy, and other atmospheric parameters using 31 explanatory leaf characters. Given a difference in leaf-estimated MAT or moist enthalpy between contemporaneous, synlatitudinal fossil floras—one at sea-level, the other at an unknown paleoelevation—paleoelevation can be estimated. These methods have been widely applied to orogenic settings and concentrate particularly in the Western US. We compare the LMA and CLAMP approaches, and develop two new models for estimating elevation: (1) simple linear regression of elevation against mean leaf area and (2) Smooth Leaf Altitude Proxy (SLAP), a procedure for reducing MAT and P by latitude for estimation of elevation. These methods have the resolution to detect paleoelevation in the Western Cordillera above 2 km, which would constrain a fundamental variable in tectonic and paleoclimatic models.
Elizabeth O’Leary and Steven Manchester
Florida Museum of Natural History
Fruit types in Rhamnaceae vary from drupes to schizocarps, nuts, and variously winged fruits. Extant genera in this family with the winged fruit type include Crumenaria, Gouiana, Paliurus, Smythea, and Ventilago. Although these fruits are distinctive enough to be identified to the generic level, their fossil record is poorly known. Paliurus fruits are fairly well known, with the earliest record in the Eocene of western North America, however the fruit fossil record of the other genera remains scanty.
These fruits are striking similar to those of extant species of Gouania in the apical region and the distinctive venation pattern. Typically, fruits of this genus have three wings composed of the junction of two valves which may be thick or thin, fused or free. The fossil specimens only show two wings; this might represent a true difference between these specimens and extant Gouania, or the fossil may represent only a single valve of the fruit. The "stalk" observed in the fossil seems to correspond to the stipe in extant fruits. The position of the hypanthium and disk in extant fruits seems consistent with what was observed in the fossil specimens; however the fossils do not clearly show these features. Overall, these similarities seem to show an affinity with the modern genus Gouania.
Today, Gouania is found in North America, Africa, Asia, and the Madagascar/Indian Ocean region. Some authors have attributed this biogeographic pattern to long distance dispersal citing estimates of divergence dates between Gouania and related genera to the early Miocene when these continents were quite distant. However, if this fossil truly represents the genus Gouania, the divergence date may be much earlier, and long distance dispersal may not need to be invoked to explain this distribution.
Andrew C.L. Postnikoff and J.F. Basinger
University of Saskatchewan, Saskatoon, Sask., S7N 5E2, CANADA
The Paleocene Ravenscrag Formation is exposed throughout southern Saskatchewan and adjacent southeastern Alberta. In the vicinity of the type locality, the paleoflora of Ravenscrag Butte, found in the Cypress Lake map area of western Saskatchewan, has been recently researched, while the paleoflora to the east, in the Willow Bunch Lake map area was last compiled in the 1930s, and is in need of revision due to advances in the understanding of Paleocene floras. Numerous productive paleobotanical localities have been identified in the Willow Bunch map area, particularly near the Big Muddy Valley, with ages ranging from the earliest to middle Paleocene. A survey of these localities has identified three distinct florules. The first florule occurs within 10 m of the KT boundary, and is a conifer-dominated swamp forest with Glyptostrobus and Metasequoia present in all localities. Other elements include broadleaved angiosperm trees, aquatics, ferns and mesic conifers such as Mesocyparis. The second florule, which occurs much higher in section, is also conifer-rich. However, it is dominated by Mesocyparis, which has been interpreted to thrive in a better-drained environment. Glyptostrobus and Metasequoia are rare elements in this florule. The other elements in this florule occur rarely, if at all, in the first florule. The third florule, from the southern branch of the Big Muddy Valley, also occurs higher in section, albeit with a poorly constrained stratigraphic relationship with the second florule. This florule is distinct from the other two, as it is angiosperm-dominated, with only rare conifers and ferns. The majority of these angiosperm leaves are lanceolate, unlike the broad leaves of the Platanoids and Cercidiphylloids that typify the first florule. The conifers in the third florule consist entirely of Mesocyparis. It is unclear whether these two high-section florules reflect a general change to the flora, or if these florules represent different aspects of a single, regional vegetational mosaic, from lowland swamp to upland forests. The fossil flora of southeastern Saskatchewan is important as a link between Paleocene floras to the paleo-northwest in Saskatchewan and Alberta, and those of the Williston Basin to the south.
Surangi W. Punyasena
University of Chicago/Committee on Evolutionary Biology, Chicago, IL, 60637, USA
Paleobotanical data have been used in many forms to reconstruct past climates, from the identification of functional types, to biome-level characterizations, to the quantification of morphological characteristics. But for the palynological record, the most important variable remains the taxonomic makeup of an assemblage.
One of the presumed limitations of using taxonomy to reconstruct climate has been the assumption that the diagnostic relationship between plant and climate is at the species level. Sister species are often found in very different habitats. This is particularly true in the tropics.
Results of a nearly continent-scale analysis of tropical South American vegetation, however, suggest otherwise (Punyasena et al, submitted). We demonstrate that local differences in the richness and abundance of individual plant families can be attributed to climate by identifying covariation between the number of species and individuals within plant families and eight temperature and precipitation measures using the eigenanalysis method of two-field joint single-value decomposition ("joint SVD"). Data were taken from published forest transects and climatology.
Even at the taxonomic resolution of the plant family, several large and ecologically important taxa, including Fabaceae, Bignoniaceae, and Arecaceae, display clear covariation with changes in temperature and precipitation. Most notably, the diversity of many lowland Neotropical families may be more a factor of spatial differences in temperature than precipitation.
Using these climatically sensitive families, I test the feasibility of a probability density function ("pdf")-based reconstruction of temperature and precipitation using family-level data. The resolution and utility of the approach with Quaternary and Cenozoic palynological data will be discussed, including the need to test whether the climate space of tropical plant families remains constant through geologic time.
Heather L. Sanders & Gar W. Rothwell
Integrated studies of paleobotany and developmental genetics provide new perspectives on the evolution of fundamental plant form. The frond of Buteoxylon gordonianum from Oxroad Bay is particularly enlightening for understanding the evolution of stem-leaf organography in seed plants. The shoots have helical phyllotaxis and consist of regions of dense frond production separated by regions of long internodes. The frond consists of terete axes that dichotomize equally and unequally in a cruciate fashion to form a three dimensional organ that resembles the above ground axes of the whisk fern Psilotum nudum. The frond dichotomizes sparsely at the base and densely at the distal end, with an angle of about 90o between successive branchings. This basic architecture is also reflected in the fronds of the most ancient reconstructed seed fern, Elkinsia polymorpha, and other ancestral spermatophytes such as Moresnetia, Pitus, and Diplopteridium. A cruciately forking system appears to be the ancestral architecture of the axes that gave rise to spermatophyte leaves. Using Buteoxylon as a basis for comparison with the morphology of more derived leaves, the sequence of steps in the evolution of leaves is identified. The most ancient fronds illustrate the pattern of character changes that result from specific developmental alterations. Characters that define leaves include determinacy and ad/abaxial identity. The frond of Buteoxylon is a basically radial organ, with architecture reminiscent of ancestral systems of axes, but is much smaller than the shoot. The structure of the frond suggests that the first step in the evolution of the frond of spermatophytes was determinacy and ab/adaxial identity is a more derived character.
Selena Y. Smith and Ruth A. Stockey
Department of Biological Sciences, University of Alberta, Edmonton, Alberta, T6G 2E9 Canada
A single ovulate cone has been found in a large calcareous concretion collected from Cretaceous sediments near Ono, California. The abraded cone measures at least 16 mm in diameter and 25 mm in length. Co-occurring remains include an ammonite, bird bones, moss, fern petioles and pinnules, several types of taxodiaceous and pinaceous leaves and shoots, conifer and angiosperm wood, and a pinaceous pollen cone. Material was sectioned and studied using the cellulose acetate peel technique. The pith is parenchymatous and surrounded by a moderately dissected stele. Xylem shows one growth increment, and secondary xylem lacks resin canals. The inner cortex is parenchymatous with resin canals, while the outer zone is strongly sclerotic. Small uniseriate trichomes are found on the cone axis. Vascular traces to the ovuliferous scales arise as two lateral traces that later fuse to form one abaxially concave trace. Keeled bracts are parenchymatous with a single terete trace and two lateral resin canals, and separate from the ovuliferous scales at the margins first. Ovuliferous scales are adaxially parenchymatous and abaxially sclerenchymatous. Cortical resin canals branch to enter the cone-scale complexes on the abaxial side of the vascular trace. These branch to form two adaxial resin canals in the interseminal ridge, and distally to form multiple resin canals abaxial, adaxial and in between the small vascular bundles of the ovuliferous scale. Few seeds are preserved in the cone. Characters of the fossil are compared to pinaceous ovulate cones of living and fossil (Pararaucaria, Pseudoaraucaria, Obirastrobus and Pityostrobus) genera, and show affinities with the genus Pityostrobus. Of the living genera, the new fossil is most similar to Picea. Leaves with similarities to those of extant Picea are also present in the nodule, but lack the characteristic rhomboidal shape in cross section. The large number of species of Pityostrobus demonstrates that the Pinaceae were undergoing rapid diversification in the Cretaceous prior to the establishment of modern genera.
Witt Taylor, Kathleen B. Pigg, and Jack A. Farmer
Arizona State University, Tempe, AZ 85287-4601, USA
Hydrothermal spring deposits
have long been a focus of interest to both geologists and paleontologists.
The first critical studies, by Weed (1885) initially determined the nature
of hydrothermal springs. Today, scientists have added to this rich base
by examining not only geological questions, but also questions regarding
the role thermal springs play in preserving fossil material. These deposits
preserve fossils readily by the mixing of higher temperature supersaturated
solutions from thermal springs with the cooler waters of surrounding pools.
Biotic materials in the pools act as nucleating points for the rapid precipitation
of opaline silica and other minerals. Because the discharge solution from
the sinter influences the local biota, the presence of a particular group
of organisms can be used to infer the temperature of the exit waters.
Elisabeth A. Wheeler, Shirley Rodgers, Troy Simpson, Jeff Bartlett, Kathy Brown.
The InsideWood database for modern dicots has relatively broad coverage with wood anatomical information for some 200 families and 2,500 genera. The 5,500 + description records represent at least 8,000 species. One "problem" with the database is that some genera have homogeneous wood anatomy, while others do not, so that the number of species any one description represents varies. Conversely, some species (usually those of commercial importance and with a wide geographic range) have multiple descriptions as the observations of different authors vary. The original database was based on work done by L. Chalk, Oxford, during preparation of "Anatomy of the Dicotyledons." The wood anatomical literature and original observations have been used to edit this database. Editing is on going (never-ending?). Although far from perfect, this database can used to address questions about the general distribution of selected wood anatomical characters, character correlations, and patterns of wood anatomical diversity. It is useful for assessing the affinities of fossil dicot woods to extant woods.
One major objective of the InsideWood web site is to provide an interface to search the database by the coded features of the International Association of Wood Anatomists (IAWA) used in the description records. A very fast web-accessible interface to the InsideWood databases has been developed using ColdFusion, Oracle indexes, and pre-formatted display data. Wood anatomical information can be retrieved by IAWA features, scientific names, or keywords (e.g., common name, geographic source). A database for fossil woods (some 1500 entries) is being formatted so that it can be added to the InsideWood web site and searched, as is the modern wood database.
Another major objective of the site is to serve as a repository for photomicrographs of wood structure. Currently, over 23,000 digital images of modern woods are available on-line, with contributions from the National Herbarium of The Netherlands, Royal Botanic Gardens, Kew (U.K.), CSIRO (Australia), Royal Museum for Central Africa (Belgium), FFPRI (Japan), USDA Forest Products Lab, Catholic University – Leuven, Belgium, University of Hamburg (Germany), North Carolina State University. Some images are not attached to wood anatomical descriptions. Luna Insight can browse the image database separately, and images can be retrieved by family, genus, species, contributor, or any field configured as searchable from Insight. There is the capability to "zoom-in" and to manipulate images for incorporation into instructional material and presentations.
THE ALBIAN–CENOMANIAN (OAE1D) SEQUENCE BOUNDARY USING PLANT CARBON
ISOTOPES: DAKOTA FORMATION, WESTERN INTERIOR BASIN, USA
of Natural Resources
& Survey Division
Geography & Geology
Analysis of bulk sedimentary organic matter and charcoal from an Albian–Cenomanian fluvial-estuarine succession (Dakota Formation) at Rose Creek Pit (RCP), Nebraska, reveals a negative excursion of ~3‰ in late Albian strata (oceanic anoxic event 1d – OAE1d). Overlying Cenomanian strata have δ13C values of –24‰ to –23‰ that are similar to pre-excursion values. The absence of an intervening positive excursion (as exists in marine records of the Albian/Cenomanian boundary and OAE1d) likely results from a depositional hiatus. The corresponding positive δ13C event and proposed depositional hiatus are concordant with a regionally identified stratigraphic sequence boundary in the Dakota Formation (D2), as well as a major regressive phase throughout the globe at the Albian/Cenomanian boundary. Data from RCP confirm suggestions that some positive carbon-isotope excursions in the geologic record are coincident with regressive sea-level phases, and that OAEs do not always occur during transgressive phases. We estimate using isotopic correlation that the D2 sequence boundary at RCP was on the order of 0.5 Myrs in duration. Several other sections including outcrop and cores have also been analyzed indicating that a similar duration is evident for the region. Therefore, interpretations of isotopic events and associated environmental phenomena, such as oceanic anoxic events, in the shallow-marine and terrestrial record may be influenced by stratigraphic incompleteness. Further investigation of terrestrial δ13C records may be useful in recognizing and constraining sea level changes in the geologic record.
by Lilla Hably
Hungarian Natural History Museum, Botanical Department, 1476 Budapest, POBox 222, Hungary
Two new occurrence of the Sloanea genus were recorded from younger layers of the Early Oligocene of Italy in Chiavon and Santa Giustina. In Chiavon a new fossil Sloanea species, Sloanea peolai (Principi) Hably, Tamás & Cioppi, was described based on its leaf remains. The macromorphological traits of S. peolai are significantly distinct from other Sloanea species hitherto described which is also corroborated by morphometric measurements. In contrast to Chiavon where Sloanea leaves are macromorphologically preserved a leaf with preserved cuticle was recorded in the flora of Santa Giustina.
At the same time an other Sloanea species, S. elliptica (Andreánszky) Z. Kvaček & Hably was proved to be a dominant element in the flora of Santa Giustina. The species was described earlier with numerous systematic names from this flora. S. elliptica has been recorded so far solely from the Inner Carpathian Region, from the Oligocene of Hungary (Budapest, Eger-Kiseged) and Slovenia (Rovte). The Early Oligocene flora of Hungary and the flora of Santa Giustina share several taxa in addition to Sloanea elliptica, e.g. Daphnogene sp., Comptonia acutiloba Brongniart, Comptonia schrankii (Sternberg) Berry, Smilax sp., Zizyphus zizyphoides (Unger) Weyland, Eotrigonobalanus furcinervis (Rossmäsler) Walther & Kvaček from among which the latter species is dominant in both floras.
In Europe Santa Giustina is the only flora where the two Sloanea species must have co-occurred. In the flora of Budapest S. elliptica and S. eocenica presumably represent the leaf and fruit remains of the same species. Both the macromorphological traits and cuticular structure of the leaf remains from Santa Giustina well correspond with those of the specimens from Slovenia and Hungary (Budapest, Eger-Kiseged). Since these floras are contemporaneous S. elliptica must have occupied an extensive area in the central and southern part of Europe during the Oligocene. The tropical-subtropical climatic requirement of the genus corroborates the idea of a quite warm climate of these areas during the upper part of the Early Oligocene.
I am thankful to Dr. J. Tamás (Hungarian Natural History Museum, Budapest, Hungary), Dr E. Cioppi (Univ. Florence, Museo di Storia Naturale, Florence, Italy) and Dr M. C. Bonci (DIP.TE.RIS. Genova) for their valuable help and cooperation. This research was supported by the Hungarian Scientific Research Fund (OTKA T043327).
Research using carbon-isotope ratios (δ13C) in terrestrial organic matter has been used recently to reconstruct global climate, environments and ecology of ancient plant ecosystems. In addition, carbon isotopes in charcoal, cuticle and bulk terrestrial organic matter from stratigraphic sections have been used for correlating marine and terrestrial sequences. Although many researchers have looked at isotopic variation from leaf-to-leaf and from plant-to-plant, there has been little attention on potential variations in single leaves. This is particularly important since cuticle is abundant in terrestrial sequences and survives the process of fossilization and diagenesis. In this study, we have investigated the δ13C variation within modern Gingko, Equisetum, Maple, Pine and Spruce. Within all the plant specimens so far analyzed we have found significant δ13C variation (up to 3‰) and a trend from more negative (12C-enriched) values at the leaf margin to more positive (13C-enriched) values at the stem (petiole). We conducted a similar analytical approach to complete fossil leaves from the mid-Cretaceous Dakota Formation, Nebraska. Similar δ13C variation and a trend towards more positive values at the stem were also found in the fossil specimens regardless of size and genus. Therefore, we suggest that an original carbon isotopic pattern within the leaf is preserved during the process of fossilization. The dominant compositional sources for carbon-isotope variability in modern plant matter are cellulose, lignin and epicuticular waxes, with the latter dominating leaf cuticle. Epicuticular waxes are 12C-enriched compared to bulk plant material, lignin and cellulose. We propose that the compositional change between higher wax abundance in leaf material and lignin in stem/wood material is the dominant factor behind the δ13C variation in modern and fossil leaves. The intra-leaf variation found in this study suggests using caution in the interpretation of δ13C in leaf cuticle fragments and bulk terrestrial organic matter for paleo-environmental and -climatic investigations.
Paula J. Mejia¹, David Dilcher¹ and Carlos Jaramillo²
¹ Florida Museum of Natural History, Gainesville, Florida, 32611, USA
² Smithsonian Tropical Research Institute, Panama City, Panama
One of the major unanswered questions in plant evolution is when and how angiosperm diversification took place. It is widely believed that angiosperms originated in the tropics and then radiated to higher latitudes to become the dominant component of terrestrial plant ecosystems worldwide by the end of the Cretaceous. However, the majority of previous work on tropical palynofloras has used mostly qualitative data. In this study we use quantitative palynological data from the Lower and Upper Cretaceous sediments of the Upper Magdalena Valley in southwestern Colombia to assess the diversity and abundance of early tropical angiosperms. Contrary to accepted wisdom, we found that angiosperm pollen was neither the most diverse nor the dominant element in the tropical ecosystems studied. This was found to be the case in both the Lower and the Upper Cretaceous. In fact, when compared to sediments of similar age from North America and Europe, it appears that the higher latitudes rather than the tropics maintained a higher diversity and greater relative abundance of angiosperm pollen during the Lower Cretaceous. Although preliminary, this study suggests that perhaps angiosperms diversified and radiated from high to low latitudes, and highlight the importance of expanding our understanding of tropical ecosystems during this time of angiosperm evolution and geographical radiation.