Canadian Association of Palynologists
 

Fossil Plants and Spores: Modern Techniques

Jones, T. P., and N. P. Rowe (editors), 1999.

Geological Society, London. 396 pp., ill.; £ 29.00; 1 kg.

Reviewed by Jan Jansonius, Visiting Scientist,
GSC-Calgary, Calgary, Alberta


Seventy-eight authors (listed, complete with e-mail addresses) wrote 60 chapters comprising 333 pages; most chapters run four to six pages in length. In order to keep things more manageable, the chapters are grouped into 10 parts; some chapters could with equal justification have been placed in another part. There is no simple way to convey what the book is about, as its many chapters are dissimilar in style and substance. I therefore review each chapter in numerical order, and try to provide a thumbnail sketch of what is contained in each; I did abbreviate some chapter titles. [In square brackets, I introduced some personal comments or thoughts in a few chapters dealing with subject matter where personal experience gave me confidence.] For chapters dealing with subject matter with which I am unacquainted, I try only to give a brief summary of what to me appear to be salient points. In one of the first sentences of each chapter review, I introduce the name(s) of its author(s).

The most important question should be answered right up-front: yes, I consider this to be a useful reference book for any institution where palaeobotany is practiced and taught; its price makes it affordable even for individuals as a personal reference book. In overall organization the book has remarkable similarity to Kummel & Raup's (1965) Handbook of paleontological techniques, although this title is not included in the References. Kummel & Raup is clearly out of date in many (but not all) respects, so an update is welcome. However, in comparing the two, it occurred to me that both suffered from too permissive attitudes on the part of the editors. This resulted in a number of small inconsistencies (such as a reference to "Appendix 3", where there is only one Appendix). In the new "Modern Techniques" I also find a lot of overlap between some chapters. If that had been weeded out, space could have been found for more in-depth treatment of the details of various techniques.

PART 1 - EXTRACTION TECHNIQUES. The coverage from one chapter to another is uneven. Several authors provided much useful information, but then in another chapter, more or similar information on the same topic would be given, if in another context. It appears that the editors had not enough time to go another round of internal reviews to straighten out inconsistencies, or make cross- references. The reader may be short-changed if he turns only to the chapter that he thinks would answer his immediate questions; rather, he should keep on reading.

  1. Locating and collecting. Rowe & Jones point out the need for accurate data for documenting the location of each sample. After a general survey of the target area, including inspection of scree slopes, compass bearings must be plotted to place the selected location on a map. Photos from various distances of the sample location make it easier to find again at a later date, while close-ups of the sampled bed help to pinpoint its exact placement. Through many such basic, common-sense recommendations, the authors ensure that novice collectors acquire a firm foundation for establishing sound practices in their field work.

  2. Extraction of lignitic and fusainized plant mesofossils from unconsolidated sediments. Penny discusses, in two pages, the type of sediments that have yielded useful fossil material, and some of the neat conclusions that have been based on them. His instructions for their extraction, however, are rather general (consisting mostly of references to some publications by workers from the era 1926-1988), and do not constitute a systematic general scheme useful for novice workers. Although various possible steps are documented by references to particular papers, these apparently should be at hand before the processing begins in order to understand the purpose of each procedure.

  3. Extraction of meso-/megafossils by bulk maceration. Wellman & Axe state that "certain modes of preservation" result in spectacular and informative fossils, but do not detail what the secret of such preservation is. However this may be, such fossils can be extracted by bulk acid maceration methods (as alluded to in Ch. 2). The instructions for a technique derived from standard palynological processing are clearly explained, but don't include a warning to do steps involving acids in a fume hood (or cupboard); many novices are not aware of the health hazards of these acids (HF can kill, HCl will damage soft tissues).

  4. Extraction of small palynomorphs. Batten sets out a detailed protocol for processing small acid-resistant fossils, from both Quaternary and pre-Quaternary strata. He is meticulous (although the quantitative composition of some chemicals is not explained, e.g., Schulze's reagent) and clear about hazards and protection, and explains the reason for each consecutive step. Still, beyond the well-established basics, I found no reference to some recent developments, such as methods to liberate organic fossils from the matrix without use of chemicals (as referred to in Ch. 24, p. 126); or, automated processing (as developed by Jones and Wrenn, amongst others, and used in off-shore drilling, and Antarctica). I would have liked an explanation on how to clean sintered glass filters so as not to risk contamination. Batten makes no difference between mounting and embedding media, or which embedding media are most suitable for examination under fluorescence illumination. There are few insider tips (e.g. that touching the rim of a sieve with an ultrasonic probe will speed up the sieving procedure dramatically). The ultrasonic probe is mentioned as an aid to remove unwanted amorphous organic matter, but details on how this works are found only in Ch. 31 (p. 165). All in all, though, this chapter gives a solid set of instructions that should help the novice considerably.

  5. Extraction of large palynomorphs. Pearson & Scott explain the steps in a large flow chart detailing techniques for concentrating fossil remains of 180 µm to 5 mm in size; they also pass on some handy tips of the trade. A plate of SEM micrographs shows what kinds of fossils are under discussion: fossil wood charcoal, charred flowers, leaf cuticle showing epidermis and stomata, sporangia (with pollen), arthropod cuticle, spores and pollen in coprolites, megaspores, etc. Inexplicably, the authors state that green rocks are more productive (than red or brown ones). My experience is that green rocks may be very poor in palynomorphs, a sentiment supported by Batten, in Ch. 37 (p. 195.) The authors prescribe adding kerosene to certain dried shale to make it disintegrate. [This seems to refer to a long discarded technique used in foram work: dry shale chips in warm beakers; cover shale in warm Varsol; decant not-absorbed Varsol (recycle); add boiling water to vaporize absorbed Varsol; vapor pressure would break up shale; wash with household detergent]. Nowadays, the surfactant 'Quaternary-O' is added to help break up the clay.

  6. Extraction from peat, lignite, coal. Bruch & Pross set out protocols for laboratory treatment of various organic matrices, and do so in a precise, well reasoned manner. They discuss standard (default) procedures, but also elaborate alternatives that may be more suited to special modes of preservation. Importantly, they specify which chemicals are particularly hazardous, and what protective measures are to be taken when using them.

PART 2 - MORPHOLOGY. Several of these chapters are rich mines of pertinent information; a few appear to have missed the target, the authors misunderstanding what the editors expected from them. The editing appears to be rather lax: apart of the polypropylene versus nylon issue I mention in Ch. 12, there is no cross-reference in Ch. 11 to Ch. 21 (which deals with the ultrastructure of cuticle).

  1. Dégagement of macrofossils. Large plant fossils (preserved as 'adpression' [compression or impression] or petrifaction) are often exposed by cleavage of a rock that runs somewhat oblique to the plane of the fossil. Fairon-Demaret, Hilton & Berry describe the technique of using needles and a small mallet ('dégagement') to remove excess matrix from a specimen, and explain in clear detail various steps, including things like how to keep the needles sharp. It is important to realize that the tools for exposing fragile plant fossils must differ from the more aggressive ones routinely used to prepare hard animal remains.

  2. Plant and spore compression. Chaloner summarizes a number of papers on experiments on models of plant fossils, and the effects of sediment load and infill on the shape of fossil remains. Compression fossils exposed in cleavage surfaces are simulated and compared with actual compression fossils. By burning off the compressed coaly matter remaining on the cleavage surface, a true impression may be exposed, from which a mould can be made. Spores (and pollen) compress in different manners, and the various folding patterns may help in analysis of the original architecture; the diameter of a flattened and distorted spore may be up to 140% of that of the original diameter

  3. Macrophotography. Rowe discusses the technical requirements for producing images of suitable quality for reproduction in publications and research. He deals particularly with fossils between 1 and 30 mm, i.e. those falling between standard photography and those needing a microscope for proper observation, including compression material, transparent peels and thin- sections. He explains the calibration steps to ensure sharp focussing, using modern and older equipment, as well as the significance of 'f values' and the effects of small versus wide aperture settings. Shutter movement and film transport may cause the focus to shift, resulting in a blurry image. Lighting is also a critical factor at high macromagnifications; the angle of the light beam may show or suppress the illusion of three-dimensional structure. Appropriate contrast must be maintained, by adjusting color value and intensity of the light source, or the use of polarizing filters. In transmitted light, the problem is how to ensure an evenly white background. Finally Rowe discusses how selection from various film types and different development procedures may affect the ultimate result.

  4. Light microscopy of fossil spores. Coxon & Clayton are not very forthcoming in dealing with light microscopy. They do mention the existence of phase contrast and Nomarski interference contrast illumination, but give no help on how such systems are to be set up for optimum results. Yet, a book as the one here reviewed should answer as many questions on that score as might be raised in far flung areas, where representatives of optical companies may not be readily available for setting up and maintaining instruments. Neither would these explain how to interpret the images deformed by the 'contrast' modes of illumination. The authors rather veer off tangentially into a paragraph on mounting media, one on vitrinite reflection (although the use of incident light is not further discussed), and one on taxonomic difficulties met with in evaluating preparations of various geological ages. The remaining text deals with the more common morphologies of palynomorphs as they appear during the geological record, and the structural layers found in the exine of an angiosperm pollen. A color plate shows photographs of a Convolutispora in Nomarski interference contrast and normal transmitted light, as well as in UV fluorescence illumination (although this technique is not mentioned in the text), and a few more spores/pollen, mostly in interference contrast mode, but none in phase contrast.

  5. Light microscopy of cuticles. Kerp & Krings take more than half of the chapter to deal with sample selection, preparation and slide mounting techniques. The microscopy section gives useful information on film selection and illumination, particularly as it pertains to fluorescence microscopy. Cuticle is the general name for the waxy coatings of external plant surfaces, on the inside of which the cellular structure of the epidermis is permanently reflected. The chemical composition of cuticle is not addressed here (it is found later in Ch. 21).

  6. SEM of mega- and mesofossils. Collinson first discusses the advantages and risks involved in subjecting specimens to SEM observation; she then adduces a number of examples of interpreting observed features by comparing fossil with related extant forms. In the next five pages she deals with preparation of specimens for the SEM, starting with cleaning. (I was puzzled by the caution to only use polypropylene - not nylon - sieves for retrieving specimens directly from an HF bath, whereas in Ch. 11, p. 54, Kerp & Krings specifically advocate the use of nylon sieves). She then discusses the application of natural and induced fractures, and gives some tips on how to expedite drying. Mounting the specimen requires consideration of the type and size of stubs; choice of adhesive, and their arrangement in multiple mounts, application of silver dag, and possibly a base of photographic film for cuticle and other curly specimens, and finally applying the correct coating. She also addresses problems encountered in dealing with permineralized material or moulds and casts. SEM photos are generally produced by traditional photography, although electronic methods are increasingly available; both methods are discussed, including such details as KV (electron voltage) and spot size (final aperture) settings. Finally, for very vulnerable specimens, the procedure of low vacuum (LV SEM) is discussed, as well as ESEM (environmental SEM), where specimens can be observed in their natural state, even when immersed in water. This chapter has many practical hints and directions, derived from hands-on experience. In Plate 12.1, the legends refer to the size of the scale bar for each photograph, yet there is only one distinct bar, in Fig. m (possibly also one in Fig. j?):does the bar in fig. m apply to all figures? That is not the style in other plates.

PART 3 - ANATOMY. There is a certain dichotomy among the chapters in this section: the first ones dealing with laboratory techniques for preparing certain types of preservation for direct visual observation (as peels, thin sections, polished blocks), the last two with much more abstract mathematical and mechanical analyses. The rationale for combining these under one title ('Anatomy') is not clear to me. All chapters give either direct instruction, or abundant references.

  1. Acetate peel technique. Galtier & Phillips provide detailed instruction on the steps in the standard procedure: the 'etch,' selecting the best piece of acetate sheet, removing, storing and mounting peels, and the liquid peel technique. They also discuss the type of mineral matrices, and the various types of fossilization in which the peel technique was successfully applied. They also refer to Ch. 22, where further refinements to the technique are discussed that facilitate examinations at higher magnifications.

  2. Embedding techniques. Jones & Rowe outline the underlying principles when devising embedding protocols, especially for examination under normal light. (Techniques more suitable for electron microscopy are discussed in Ch. 12, p. 21-24.) The methods suitable for a palaeobotanist generally differ from the strict protocols designed for coal petrographic analysis [ISO 7404/2 - 1985(E), International Organization of Standardization methodologies, which are not widely available in libraries]. Some of the resins used can 'sensitize' the skin, some are highly carcinogenic. A difference is made between 'surface' and 'impregnation' embedding'; cold-setting polyester, cold-mounting epoxy, hot setting epoxy, cyanoacrylates and other resins are discussed, as well as which ones are mutually compatible for use in composite embedding. The production of moulds, e.g., for embedding fossils in preparation for reflected light microscopy, are discussed, and finally the authors describe some case studies. It is obvious that they write from experience, and many practical hints are included.

  3. Thin sections and wafering. Hass & Rowe provide a similarly well-documented set of instructions on how to prepare thin sections (in which cell walls replaced by silica can be observed as well, unlike in peels). These can be made so thin that they may be examined from both sides. They discuss temperatures for mounting media, grinding procedure, whether or not to mount coverslips, choice of saw blades, sectioning, polishing of wafers, etc.; many tips are obviously based on thorough personal experience.

  4. Polished blocks and reflective light microscopy. Jones concisely explains the principles and potential of RL microscopy for palaeobotanists, rather than as used by coal petrologists or organic geochemists: using RL for observing structural or taphonomic information not made visible by other techniques. He gives much detailed how-to information on polishing the block, on the optic principles of the microscopes used and their alignment, calibration and taking readings, and on interpretation of quantitative results. As I am not familiar with this technique, I should have liked to see a plate showing examples of what can be brought out by RL that remains hidden in other observational modes.

  5. Opaque petrifactions. Kenrick explains the chemistry underlying the deposition of iron sulphide pyrite (framboids), and its oxidation products (e.g., limonite). As these are more or less opaque, transmitted light often will not penetrate. Pyritized specimens are prone to deterioration during storage. Histological detail in plant tissues permineralized by these minerals can be brought out by reflectance imaging; or, by selective removal of the mineral and transferring the organic remains to a translucent embedding medium. (In plant tissues, cell walls often remained intact.) SEM, particularly the use of atomic number contrast imaging with polished surfaces, or topographic imaging with etched surfaces, also will yield excellent images. Kenrick deals particularly with modifications of the embedding, polishing and peel techniques as discussed in Ch. 13 and 14 (to which they refer the reader). On a plate, photographs resulting from optical (reflection) methods are compared with images from SEM observation.

  6. Lignified and charcoalified wood. 'Lignified' means that wood was exposed to anaerobic conditions and partially degraded by microorganisms (possibly over a long period) before final incorporation in low-grade coal. Charcoal, chemically inert, results when wood is heated in oxygen-depleted conditions. Figueiral describes a method for converting lignified specimens into charcoal, so that their structure may be rapidly examined using reflected light or SEM, and discusses the advantages and disadvantages of this method. Basic preparation methods involve sectioning (again: adjusted to this method), and mounting and/or embedding procedures. Fractured surfaces may be observed directly (and can be oriented to optimal angles when observed on a bed of poppy seeds).

  7. Fabric analysis and plant anatomy. Stein & Hotton deal with the quantification of the anatomic analysis of tissues in fossil plants, and comparing these with modern forms. This approach helps to unlock a wealth of new information. Various methods for doing this are discussed. However, the authors believe that analysis of cell and tissue fabrics offer the best insight into the relative capacity and timing of growth (increase in size) of individual cells. They developed, and here explain, a method of micro-computer assisted data collection. From hereon, the well-illustrated chapter presumes presence of a fair amount of mathematical background (not in the ken of this reader), but appears to be logically coherent and systematically written.

  8. Biomechanical analysis. Numerous biomechanical studies have investigated the size, shape and overall posture of plants, in order to better postulate the height and habit of fossil plants based on their stem structure, branching patterns, etc. Speck & Rowe here outline a method for empirically investigating the growth forms of fossil plants by recalculating and comparing the biomechanical properties of stem segments from different ontogenetic stages. This eventually involves quantification being recalculated in a series of equations, which have been applied to a number of Palaeozoic plants. One of the problems with this method involves the proof of conspecificity of disarticulated fragments of fossil plants. As for how to do this analysis, one presumably should consult the numerous papers referred to in the text.

PART 4 - ULTRASTRUCTURE. This short part deals with SEM/TEM examination of various plant tissues, and thus has more coherence than some of the other parts. All chapters are to the point, mutually compatible and complementary.

  1. Ultrastructure of fossil cuticle. Taylor begins with recapitulating some of the common preparation techniques (which overlap those given in Ch. 11), but soon veers off into more specialized regions, where the samples are prepared for SEM and TEM observation. Even small fragments of mineral grains adhering to the cuticle may ruin a knife used to make ultrathin sections. Various stains can be used, that will help to show the various heterogeneous organizations (structure) of the cuticle, which even may vary in a single species, depending on which part of the plant was sampled.

  2. Ultrastructure of plant cell walls. Jones & Rowe discuss SEM and TEM methods of examining the cell wall. They focus particularly on charcoals, illustrating the principles mostly with living material subjected to controlled charcoalification. They also discuss a number of artifacts that may be introduced by applying some special peel techniques, ultrathin sectioning, etc., as well as orienting cut sections. They also show how to shatter a specimen frozen in liquid nitrogen; this results in clean breaks of undeformed cell walls, the orientation of which, however, may be difficult to deduce.

  3. Megaspore ultrastructure. Hemsley & Glasspool primarily discuss methods for making suitable ultrathin sections through the megaspore wall for observation by TEM, which should be correlated with similar sections examined by SEM (as illustrated on the plate). Instructions are given on how to prepare the block from which the thin sections will be cut. Stains may be beneficial, but also can introduce confusing artifacts. Many good practical hints are provided.

  4. Ultrastructure of spores/pollen. Taylor finds that in situ pollen grains and spores are best suited for examination with TEM and SEM, as the systematic affinities implied by the associated flower or fructification provide a broader taxonomic and phylogenetic framework. Also, usually several stages of maturity can be found together, and related grains can be studied simultaneously in transparent light. Taylor stresses the importance of precise protocols and record keeping, and of making multiple (serial) sections. He deals with embedding and orientation, ultramicrotomy and staining, and stresses the importance of tapetal membranes and orbicules or ubisch bodies as additional sources of significant information. On two plates he clearly illustrates various techniques and methods.

PART 5 - GEOCHEMISTRY. A collection of applications that huddle somewhat uncomfortably under the umbrella title of this part, containing descriptions of a number of techniques and methodologies that may not be in the immediate purview of many palaeobotanists. New techniques are shown to be useful adjuncts to more mainstream palaeobotanical approaches in certain cases. I was happy to see that these chapters in particular are provided with numerous appropriate literature references.

  1. Collecting/storage of plant remains for organic geochemical analysis. Van Bergen gives a general guide for the preparation of fossil plant samples for various chemical analyses such as elemental, lipid and stable carbon isotope analysis, spectroscopy, chemolysis and pyrolysis. These tests may be applied to bulk organic carbon, as well as to leaves, wood, periderm, propagules, algae, etc. Generally, the purpose is to obtain one of four objectives: 1) to determine the 'original' composition of the tissue; 2) to establish chemical transformations related to palaeoenvironment or depositional setting; 3) to determine thermal maturity; and 4) to determine chemosystematic relationships. Sample size varies from a few grams to as little as 0.05 mg (= about two megaspores). Bare skin contact with the sample must be avoided, or mitigated in the lab by cleaning of the surfaces. Labile chemical compounds must immediately be kept in inert gases or special organic solvents. Storage, and effects of some of the more common chemicals used in extracting samples from the matrix are discussed.

  2. Carbon stable isotope analysis. Bocherens & Mariotti explain the reasons for different isotope ratios in plant material, as well as why the modern "automated carbon isotopic measurement" is preferred over older techniques. They then discuss sample preparation for this analysis, and the pitfalls that might skew the results. A schematic flow diagram of the method is given in a text figure, as well as some tables useful for calibration.

  3. Pyrolysis and chemolysis: applications to palaeobotany. Van Bergen looks at the various methods of pyrolysis (on-line and off-line), and their purposes, as well as the utility of chemolysis. Preparation of fossil material is discussed in clear detail, including extraction through the use of solvents - the latter both for pyrolysis as well as chemolysis. The palaeobotanical applications are dealt with in two sections, respectively on chemical transformations, and chemosystematics. These are illustrated with analyzed gas chromatograms of various materials.

  4. Solid-state 13C nuclear magnetic resonance. Hatcher, Pan & Maciel explain the principles of NMR, and why initially it was applicable only to compounds in solution. Development of "cross-polarization" and "magic-angle spinning" allowed study of solids, which at first was aimed at the characterization of coals. NMR techniques offer an attractive means of analyzing a wide variety of fossil plant tissues. I think the authors did a good job of explaining the various technical requirements, caveats and limitations, and they provide NMR spectra of a number of materials. Still, this is pretty specialized stuff, and not readily digested without real application.

  5. Isolation, identification and authentication of fossil DNA sequences. The scope of the research project, rather than the researcher, will define the composition, age and mode of preservation of the study material. These factors affect the probability, or even possibility, of preservation of DNA. However, for each successful analysis, there are reports of failures: it appears wise to begin with multiple samples. Golenberg gives a careful and detailed reasoning of experimental techniques, for both extraction of fossil DNA as well as testing the authenticity of putative ancient DNA sequences. His chapter is organized in sections titled: Experimental design and extraction techniques; PCR amplification and DNA sequencing; and Sample verification.

  6. Mineralogical and geochemical analyses. Williamson & Jones show how some common techniques can be applied to fossil plants and spores. They explain X-ray diffraction (XRD), which allows the precise determination of the mineralogy of permineralized plants through compiling X-ray element maps (shown in Fig. 30-1). They also discuss cathodoluminescence (CL), the infrared or ultraviolet light emission by certain materials when irradiated with electrons. Presence of more than some 1% by weight of Fe will prevent CL in most minerals. Some embedding materials (used in polished blocks) will break down under the electron beam. The geochemical section of this chapter deals with 1) Electron probe microanalysis (EPMA) using the SEM, which can do an elemental spot analysis on a surface as small as 1 �m square; 2) a similar analysis that can be done with a TEM; 3) inductively coupled plasma-atomic emission spectrometry (ICP-AES), which typically involves a powdered sample of ca 100 mg to be analyzed for either major elements or trace elements; 4) inductively coupled plasma - mass spectrometry (ICP-MS); and 5) atomic absorption spectroscopy (AAS). The last part of this section pertains to data evaluation; 'precision,' 'accuracy' and 'detection limits' for each set of analyses must be quoted.

  7. Spore color measurement. Marshall & Yule advocate that thermal alteration be reported in all descriptive studies of fossil spores. Their remarks on processing techniques largely repeat protocols described in earlier chapters. In processing, excessive heating must be avoided. [It should be born in mind that (older) cuttings samples may have been overheated while being dried on the well site.] The authors select simple non-saccate spores for gauging thermal maturity. Staplin, however, had chosen (bi)saccate pollen as the most responsive to thermal exposure; in the Palaeozoic, saccate spores would have a similar thermal response. Of course, visual estimates of thermal alteration are inherently subjective and approximate. [The composition of the organic matrix also influences petroleum source potential.] In practice, visual estimates are dependable parameters for determining whether or not a source rock has reached (oil generating) maturity, or has passed through that window, indicating that only gas can remain. Still, the table comparing some of the more commonly used spore color scales, and their relationships to the vitrinite reflectance scale, is useful. In the section on quantitative spore color measurement, the authors do not mention the work by Schwab (Appendix by Jansonius & Schwab, p. 1075- 1077, in Batten 1996b). [Schwab copyrighted an objective quantitative method, named "ICA/SPD analysis" (for "Integrated Color Analysis via Spectral Power Distribution"); whereby the percentages of red, green and blue in a beam of transmitted light are electronically measured. These values can mathematically be converted to hue, intensity (brightness) and saturation readings. Of these, only hue and intensity are required to determine the thermal maturity of a palynomorph. Hue is always variable, whereas intensity is constant (but always decreasing with increasing maturity). Schwab analyzed the type-slide sets of Staplin, Batten, Robertson Research, GeoStrat and Geochem (USA), and provided a quantitative correlation between these and the comparable reflectivity values in %Ro.] Marshall & Yule suggest a 'home-made' surrogate for expensive quantitative measurement on dedicated hardware, by converting electronically acquired images from the CTV to RGB (red-green-blue) color coordinates; the color green appears to occur in a linear pattern roughly paralleling that of the spore color indices.

  8. Bulk geochemistry as guide to provenance and diagenesis. Bateman makes a plea for much wider application of bulk geochemical analyses to palaeobotanical problems. In doing so, he focuses on two examples from Scotland: unraveling the stratigraphy, diagenesis and provenance of a series of volcanigenic horizons bearing petrified Dinantian plants; and a smaller data- matrix elucidating the diagenesis of marine horizons bearing Middle Jurassic plants from Skye. X-ray fluorescence spectrometry (XRF), and methods discussed in Ch. 30, are the most suited methodologies, but still expensive. Sections of this chapter are titled: Laboratory procedures and data acquisition; Non-algorithmic comparison, Algorithmic comparison; and a Summary. Bateman warns that under some circumstances the data may not apply to bivariate plots.

PART 6 - CONSERVATION, DATABASES AND PROTOCOLS. Although only tangentially related to 'techniques', these three short chapters provide some welcome discussions on how and why palaeobotanical problems should be investigated.

  1. Plant fossil record on the internet. Boulter describes the (1997) status of the Plant Fossil Record (PFR) database project, which is updated about twice a year, and which is accessible on the web site http://ibs.uel.ac.uk/ibs/. It contains, a.o., the taxonomic, bibliographic and morphological details of all genera included in the (three volume) Index Nominum Genericorum, that are linked to the stratigraphic age of their types as quantified by Harland's et al. time scale. A number of other databases have been incorporated in this site, such as Benton's Fossil Record 2 compilation. Boulter gives instructions on how to enter new data into this site, as well how to use it for a variety of studies such as reconstruction of biogeographical migration, evolutionary changes, etc. This web site, of which Boulter is one of the moving forces, is a monumental source of tested basic data, and should be known and used more widely.

  2. Taxonomic and nomenclatural alternatives. Chaloner gives an overview of the difficulties to be dealt with when disjunct parts of plants are found which must be dealt with in biostratigraphic or evolutionary contexts. He discusses the International Code of Botanical Nomenclature, and its requirements for validly publishing a name, dealing with priority, nomenclatural types (epitype is a relatively new concept), and the concept of "form taxa." [At the Nomenclature Session of the last International Botanical Congress (IBC), August 1999, the concept 'form genus' (which combined the concepts of the former organ- and form genus) was replaced by the new term 'morphogenus'.] He also mentions plans to design a "Biocode" that would equally apply to plants and animals, and was intended to replace the ICBN and ICZN. [The Biocode was not supported by the Nomenclature Session of the last ICB.] Chaloner further discusses some systems of 'alternative taxonomies' (parataxa), e.g., Raistrick & Simpson, Hughes' 'biorecords' and Potonié's Turma system. These now are generally of historical interest only: for most efficient communication among taxonomists, the Linnean binomial system remains the lingua franca.

  3. Curation in museum collections. Shute & Foster outline and discuss the procedures established in the Palaeobotany Section of the Natural History Museum (NHM) in London, UK. These include protocols on registration and administration, as well as conservation of impermanent specimens. In particular the problems with pyrite are dealt with clearly. They affirm the need to house collections in permanent and dedicated facilities, with continuous funding.

PART 7 - SEDIMENTOLOGY, TAPHONOMY AND STRATIGRAPHY In this part, there is a shift from techniques as practiced in the laboratory (or even in the field, with mechanical, physical or chemical aids) to approaches, computer-assisted analysis, and sound practice in the acquisition of data. These eight chapters contain much practical information and general introductions, backed up by generous references to pertinent literature.

  1. Experimental sedimentology. Nichols addresses facies analysis, which is used to interpret sediments in terms of environment of deposition. However, the bulk of his chapter deals with experiments on the behavior of charcoal particles, conducted in settling tanks, wave tanks, and flume tanks. Although of some general interest, I didn't see how his conclusions would affect better strategies for sampling or interpreting taphonomic conditions. (One question which I often pondered, is: why are so many spores and pollen flattened in a single plane, without distortion by angular sedimentary particles. Do they settle out in quiet water, together with fine clay particles?)

  2. Palynofacies analysis. Palynofacies is an important aid "for the determination of environments of deposition and the identification of source rocks for petroleum." Palynofacies analysis "requires that all types of acid (HCl, HF) resistant organic matter (OM) recovered from the ... sediment are examined." However, Batten does not give a more precise definition of what exactly 'palynofacies' is. [Only in Ch. 50, p. 270, does Traverse give such a definition.] The various classifications of the types of Particulate Organic Matter (POM), or of Palynological Organic Matter (PM), are still being discussed, and in part overlap. The difference between Unstructured OM (USTOM) and Amorphous OM (AOM) are not clearly defined, either; the latter is, however, the most important organic component of petroleum source rocks. Batten recommends making a slide after "digestion of the inorganic matrix in HCl and HF." Further treatment "may include filtering, sieving, oxidation and ultrasonic vibration." [In our lab, a ZnBr2 separation used to be done after the HF treatment, to eliminate remaining quartz and heavy mineral grains, in order to have a cleaner unoxidized PM slide.] The larger part of the chapter deals thoroughly with accumulation and handling of data, as well as applications, with particular emphasis on biostratigraphic and sequence stratigraphic studies.

  3. Particle orientation and palaeoenvironments. Bateman uses a few case studies to discuss the analysis and interpretation of macroscopic aggregate particle orientation (fabric analysis). This technique, more commonly practiced in sedimentology, is highly informative about conditions of deposition (and often, by inference, of growth), but is seriously underutilized in palaeobotany. The chapter deals with data acquisition, presentation and analysis; its last section deals with the interpretation of fabrics.

  4. Coal ball sampling and quantification. Calcareous coal ball concretions from Upper Carboniferous and Permian coal deposits are the most abundant sources of anatomically preserved vascular plants. Their quantitative analysis is of interest to palaeobiologists as well as coal geologists. Coal balls occur in layers ('zones'); they may be sampled as orientated profile, or as random samples. In the section Field sampling, Phillips & DiMichele deal with minimum sample size, and its relationship with preservation, local variation of swamp vegetation, etc. Next, they deal with quantification of the botanical composition, grit overlays allowing mapping of features of a peel; and finally, with the analysis of the quantitative data, and with the question: how well do coal balls represent the original vegetation?

  5. Taphonomy: field techniques in modern environments. Ferguson, Hofman & Denk begin their chapter with the statement that, although one must be wary of interpreting fossil assemblages in terms of present day processes, without actualistic principles as a guideline, palaeobotanical interpretations would quickly relapse into the realms of fantasy. Thus, they use the Southeastern United States (e.g., Mississippi) and the Euxino-Hyrcanian relict area (eastern Black Sea coast) as analogues for Cenozoic conditions, and describe observations and field methods for analyzing these. Among other things, they deal with: litter sampling on the forest floor; surface sampling for pollen; aerial dispersal of plant parts, their influx into lakes and large rivers, and the distance they travel; netting litter in streams; and destruction of detritus at sediment-water interface.

  6. Palaeosols. Fossil soils are parts of ancient landscapes, altered in place by past environments. Though common in non-marine sediments (and including coal seams, underclays, laterites, etc.), they cannot be transported and remain a palaeosol: they will be reduced to sediment. Many palaeosols preserve fossil stumps, leaf litter, pollen, etc., in the place where they lived. They are excellent proxies for ancient communities, and serve to anchor palaeoecological reconstructions. They are trace fossils of ecosystems, rather than of species or individuals. Retallack deals with plant remains in palaeosols: logs, leaves, phytoliths, seeds, etc., and their preservation types. He further discusses trace fossils in palaeosols, and palaeosols as trace fossils. The second half of the chapter is a thorough discussion of the petrography and geochemistry of palaeosols, and the various analytical methods that may be applied.

  7. Plant macrofossil biostratigraphy. Cleal gives a critical review of true biostratigraphic principles: dividing time periods and rock units on fossil content (not by absolute time, or lithological characters). Plant macrofossils have played a major part in thus subdividing late Palaeozoic strata; the same principles ought to be equally applicable in Mesozoic and Tertiary rocks. Cleal discusses the different kinds of (bio)zones: range zone, interval zone, multitaxon biohorizon; the taxonomic nomenclature of biozones; the kind of data on which the zones should be based. He deals with what controls biozones: changes in environment, or evolution; with the limitations of the application of biostratigraphical schemes; and, finally, with the relationship between biostratigraphy and chronostratigraphy.

  8. Spore/pollen biostratigraphy. Clayton & Coxon summarize the principles and practice of palaeopalynology for non-palynologists in a useful manner. Although this short chapter contains little new for palynologists, they explain why the approach for Quaternary analysis differs fundamentally from Pre-Quaternary investigations. Also, what kinds of palynomorphs are most useful in the major stratigraphic divisions: from early cryptospores in late Ordovician to early Devonian, to angiosperm pollen in the Cretaceous and Tertiary. Interestingly, their example of miospore zonation, Fig. 43.2, of the Tournaisian-'Strunian' interval, overlaps and provides a downward extension of that for the Mississippian published by Clayton 1966.

PART 8 - PALAEOCLIMATOLOGY. All six chapters deal with the transfer or proxy functions provided by various plant parts, as applied in reconstructions of past climates: leaves, tree rings, leaf stomata, and climatic requirements of near relatives. Between them, they contain a wealth of mutually complementary information.

  1. Fossil leaf character states: multivariate analyses. Physiognomic traits of leafs are constrained by the laws of physics, in response to functional need and environmental conditions. These determine the size/number of stomata and the size of the leaf surface area. Leafs of woody angiosperms, especially the dicotylodons, appear to have been most responsive to climate, which imparts on them a wide array of morphologies that possibly can be calibrated with environmental factors. Wolfe & Spicer discuss the significance of various kinds of leaf morphology, in particular as those reflect climate. They follow this with an explanation of the basis for, and development of, the climate-leaf analysis multivariate program (CLAMP). The compilation of the database underlying this analysis is explained in detail, and elucidated with nine plots and diagrams. Some sample applications are included, and future work is discussed. [Reference to a "CANOCO" run (p. 238) is rather cryptic; it finds some explanation in the caption of Fig. 44.1 (p. 234), but its inclusion in the Appendix is not in alphabetic order.]

  2. Palaeobotanical databases and palaeoclimate signals. Rees & Ziegler assess how palaeobotanical data can be compiled and analyzed to reconstruct palaeoclimates, ranging from local to global scales. They believe that many previous workers have underestimated the effect of climate on fossil plant distributions. A multivariate statistical approach to data analysis may be used at various scales. Sampling depends on the scale: environment (e.g., elevation) can be worked out on a local scale (10 km), whereas climate (e.g., temperature, precipitation) needs to be determined in a wider perspective (1000 km). The authors discuss why and how the palaeobotanical record should be used. Their data are extracted mainly from leaf type distributions, and thus are similar to those in the work described by Wolfe & Spicer in the previous chapter. Indeed, they also use CA (correspondence analysis), as well as CLAMP and CANOCO. They provide an example of application of their method based on some 8000 leaf genus occurrences from 950 Jurassic plant localities worldwide. These are combined with taphonomic and topographic data of each sample, and the contemporary distribution of floral provinces on palaeogeographic maps.

  3. Palaeodendrology (tree-ring analysis). Fossil tree rings are of little use for dating (unlike tree-ring analysis of 'modern' wood), but can provide detailed information about seasonality, annual growing conditions, water availability, limiting temperatures, etc. Creber & Francis outline the main methods of their analysis. Tree rings, illustrated in Fig. 46.1, are the "black box" recording the annual growth patterns of the cambium layer. Earlywood (marking spring activity) has large cells, latewood smaller ones; frost damage may produce a 'frost ring,' or drought a 'false ring.' Noticeable patterns of tree rings with different widths are called a 'signature,' which often exists also in neighboring trees. Formulas are given to calculate the 'annual-' and 'mean sensitivity.' Intra-ring cell analysis is illustrated in three plots. The authors apply their formulas for calculating the productivity of fossil forests in Tertiary Arctic, and Lower Cretaceous Antarctic locations. The final section deals with growth rings in tropical regions.

  4. Stomatal density and index: theory and application. Variations in the concentration of CO2 potentially played a role in influencing past climates; there is a need for temporally detailed assessment and quantification of past CO2 levels. Air bubbles in deep Greenland and Antarctic ice cores have provided direct evidence of changes in the last 160 000 years, that are coordinated with climates across glacial-interglacial cycles. A proxy for such direct measurements may be the analysis of stomata, because stomatal density of leaves of terrestrial plants from temperate regions responds to changes in CO2 concentration. Beerling lists some current methods for estimating past variations in CO2 content, and addresses the intrinsic and extrinsic factors that affect stomatal characters. The constraints of the latter method are pointed out. Under the heading "Maximizing the signal to noise ratio," he deals with environmental effects; temperature; water supply; irradiance; and biological effects. Heterogeneity within and between leaves impacts on the experimental procedure, and subsequent data analysis. Some applications in Pliocene, as well as Palaeozoic studies, are discussed.

  5. Stomatal density and index: the practice. Here, Poole & Kürschner provide a number of introductory references that, intriguingly, are largely different from those in the previous chapter. Although there is overlap in these two chapters, as there is in their respective titles, this one sets out the detailed protocols for sampling, measuring and analyzing stomatal data.

  6. Nearest living relative (NLR) method. A basic task of palaeoclimatology is reconstruction of parameters such as: mean annual temperature (MAT), cold (CMMT) and warm (WMMT) month mean temperature, or mean annual precipitation (MAP). All palaeoclimatic reconstructions have to rely on climate proxies. The NLR is one of the oldest techniques toward this purpose, dating back to work by Heer (1855-1859). Mosbrugger, in this chapter, deals with four types of NLR technique: those based on taxa, versus those based on 'syntaxa' (ecologically defined groups of organisms); those that aim at qualitative, versus those aiming at quantitative palaeoclimate reconstructions. He also deals with problems and limitations for these methods.

PART 9 - PALAEOECOLOGY. In the ten chapters in this part, approaches and techniques are discussed that lead to palaeoecological conclusions. Some are heavy on mathematics and statistical analysis; others lean more toward providing a sound scientific perspective for finding a solution to the problem in hand. Among them, there is a lot of interesting information, and demonstrations of methods and ways of doing business with which I was not familiar.

  1. Palynology/ecology interfaces. Traverse defines ecology essentially as the study of the environment, the organisms living in it, and the (physical and chemical) interactions between these two components. As the subjects studied by palynology have broadened in kind and variety, so the interaction between it and the environment has become more worthy of consideration. Taphonomy (dealing with what happened to the palynomorphs after the original living organic material died) is an important aspect of palaeoecology. The total palynomorph composition of the organic residue extracted from a rock is sometimes called its palynofacies. Traverse separates the two aspects of this, and recognizes these as 'palynolithofacies' and 'palynobiofacies.' Pollen analysis, almost the first kind of applied palynological study, is mentioned as a special case of the latter, and this method is extended into the Pleistocene by analysis of the Grande Pile in France, where Wollard documented the waxing and waning of forest types for hundreds of thousands of years.

  2. Techniques for analyzing lake sediments. Jackson finds that lake sediments provide a continuous record of past vegetation and environment, the ages of which often can be known in detail. He discusses various types of devices used in sediment coring. Next, he deals in fair detail with the modification of standard pollen extraction, where it is beneficial to begin the process with dissolving alkali-soluble organic compounds (humic and other organic acids); however, there is much overlap with the standard procedures that have been dealt with in Chapters 2-6. Jackson mentions the use of Lycopodium tablets as an aid to determine pollen concentration, and in the final section discusses the several international palaeoclimate databases, and programs (TILIA and TILIAGRAPH) through which data can be directly transferred.

  3. Collection and analysis techniques for palaeoecological studies in coastal-deltaic settings. Gastaldo begins by stating that many assumptions have been applied to the interpretation of Phanerophytic plant communities with relatively little actuopalaeontological data and data analysis to support or refute them. Although plant histology is much as it was since terrestrialization, and decay or preservation still depend on much the same chemical reactions, we now realize that taphonomic filters causing some plants to be less likely to be preserved than others, are facies dependent. Gastaldo discusses in detail the array of hardware, used for sampling water and bottom sediment in modern coastal-deltaic regimes, and the various ways of applying it in order to obtain actuopalaeontological data; these include rivers, bayous, bays, and marginal marine settings. Terrestrial environments are dealt with as well, with protocols for sampling for actuopalynological studies, and subsurface investigations. The last sections deal with data retrieval and data analysis.

  4. Calcareous algae: analytical techniques. Williamson, Jones & Bérubé give a concise but clear summary of the analysis of calcareous algae, which provides palaeoenvironmental information not usually found in fossil plants. Geochemical and isotopic studies unlock environmental information stored in unaltered biogenic carbonates. The authors deal with sample collection, soft sample maceration (obviously without using acids), and removal of organics and contaminants. Resin embedding usually precedes cathodoluminescence and X- ray elemental mapping, as well as SEM. X-ray element mapping. X-ray diffraction and cathodoluminescence are the most common techniques for analyzing biogenic carbonates. Stable isotope analysis for oxygen gives information on palaeotemperatures; whether this is true for carbon isotopes as well remains to be seen. An informative plate illustrates the subject of this chapter.

  5. Archaeobotany: collecting and analysis of sub-fossils. Figueiral & Wilcox state that botanical studies of remains found in archaeological settings, though conducted as early as the last century, were put on a systematic and analytical basis only in the 1960s. Preservation of the fossils is generally poor; charred remains are usually best. Sampling strategies and techniques are detailed for small objects, as well as wood. Finally, analytical methods and applications are discussed.

  6. Dendrochronology. Baillie writes an interesting account of the chronologies built up through correlating equivalent tree ring patterns: continuous chronologies go back 9000 years; the oldest living trees date back 3600 years. These datings are calibrated by carbon isotope analysis. Difficulties with this, and applications of the chronologies, are discussed in details. Comparison of ring patterns can be done visually, or with aid of a computer and special programs. Finally, problems of data gathering (e.g., from beams holding up ancient buildings) and data accumulation are addressed.

  7. 14C dating sub-fossil plants. Housley provides a practical guide to 14C dating as used to determine the age of Holocene and Late Quaternary sub-fossil plant remains. Sections of his chapter deal with basic principles, and methods of reporting. There are limitations (depending in part on the analytical method used) of age - the window of efficacy of this method is generally taken as spanning 200-40 000 years before 'present' - and of precision. Other factors potentially influencing results concern the materials submitted for 14C dating. For instance. the 'old wood' effect, in which the inner tree rings may be hundreds of years older than the outer ring of sapwood deposited just before the tree died: these must not be analyzed together. Finally, Housley deals with sample size, handling and storage, and the calibration procedure, in which variable rates of 14C production are reconciled with a central standard, that extends for at least the last 24 000 calendar years.

  8. 13C/12C in growth rings and leaves; carbon distribution in trees. The ratio of carbon isotopes of tree rings can be used to reconstruct past climates. However, trees are rather complex systems, and many circumstances may affect the distribution of isotopes within a tree; how this happens, is not yet fully known. Schleser gives a brief but comprehensive review of the method, the biological background for carbon isotope distributions in trees, the standard reference (i.e., 'PDB,' a belemnite from the Upper Cretaceous Pee Dee Formation, South Carolina). He also describes the technique of extracting the preferred parts of a tree for analysis (which is cellulose, not an aliquot of total tree material).

  9. Plant-arthropod interactions. Scott & Titchener discuss the technique of studying and interpreting the evidence of interaction between plants and arthropods: where must the evidence be looked for, how does its preservation play a role, and how can it be recognized. Wound reaction tissue on leaves may show that wounds were inflicted prior to abscission, but how does it differ from secondary fungal infection? Different types of bite damage are classified, and their significance is indicated.

  10. Plants and animal diets. Collinson discusses how a diet of plants of ancient animals can be recognized, and how all its informative data can be extracted by proper techniques. Gut contents are described, illustrated, and interpreted. Coprolites, as can be expected, also yield valuable information. The Cenozoic record of fossil mammal teeth is very informative regarding specialized ancient diets. But even things like 13C/12C ratios, reflecting the photosynthetic pathways (C3, C4 or crassulacean metabolism), can be imprinted on animals through the plants they feed on: a transition occurs in fossils of North American horses from a C3 to a C4 diet at around 7 Ma. (C4 indicating a diet of grasses).

Part 10 - INTERNATIONAL LAWS

  1. International laws, collecting, transporting and ownership of fossils. This chapter is subdivided into ten sections, each author covering one of ten different countries. Each section is about one page in length, except that for the USA, where a summary of laws governing each of the 50 states, as well as the regulations applying to Indian Reservation lands (legally not part of the USA,) cannot be dealt with so briefly. Here, Gastaldo provides two tables with addresses of the legal entities, one for the Indian Lands, the other for the individual States, from which permissions for collecting must be sought. The other nine countries surveyed are: Australia, Belgium, Canada, China, France, The Netherlands, Spain, South Africa, and the United Kingdom. This chapter makes for interesting reading, as the widely varying regulations and laws reflect cultural and historical evolutions that go far back into historical time.

REFERENCES. The references cited in each chapter are integrated into a single listing (pp. 339-373). This is rather a voluminous effort, as most chapters happily contain many citations of papers to which the authors refer for more detail. This feature is one of the more important contributions of the book.

GLOSSARY OF TERMS. The rationale for the selection of terms included here is not clear, and the definitions are not always clear either. Some definitions pertain only to certain narrow applications that are not further qualified. Some terms can also be found in the Index, and thus more complete definitions can be accessed; others are not. The Glossary occupies pp. 374-84.

APPENDIX: LIST OF CHEMICALS, EQUIPMENT AND SUPPLIERS. On pp. 385-388 is a listing of technical supplies, which is disappointingly poorly organized. Some entries are out of alphabetic order; some substances are listed alphabetical by their name ('Canada balsam'), others by the name of a similar product (e.g., Canada balsam, again listed under the entry 'PDX'). Some suppliers are listed with an e-mail address ('TILIA'), others without ('Taxon').

INDEX. Pages 389-396 contain an index of terms and subjects that I found rather skimpy when trying to locate, in later parts of the book, terms that I remembered having seen in another context earlier. Although 'chronostratigraphy' is included in the Glossary, it is not found in the Index; the word 'dag' occurs in neither, although it is used on p. 61 (as section heading), and p. 118. 'UHU' glue (p. 61) is not mentioned in the Index, Glossary or Appendix (it is a general-purpose glue from Europe, not imported into Canada). 'Lycopodium tablets' is found only in the Appendix (but are discussed on p. 276); 'homotaxy' is in the Glossary, but not in the Index (it is discussed on p. 224). For such a comprehensive book, more effort should have been put in the Index.

NOTE: This is a longer version of a review that appeared in Review of Palaeobotany and Palynology 110(3-4):259-264, July 2000. In that publication, on p. 259, column 2, line 5, "180 m" should be read as "180 µm" (in which 'µm' stands for 'micrometer').


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