The terrestrial vertebrate fossil record provides a window into the past evolution of taxa, communities, and ecosystems. It can also be used to reconstruct ancient environments, climates, and landscapes. Vertebrate fossils can document the evolution of humans and their interactions with fauna and environments. However, before the maximum potential of this record can be realized, it is essential to know the extent of temporal resolution, or time-averaging, represented by fossil samples.

Diatoms are golden brown algae (class Bacillariophyceae) whose cellular contents are enclosed between two valves or shells of silica. They are classified into groups with radial symmetry (centric diatoms) and axial symmetry (pennate diatoms). The latter are subdivided as raphid and araphid diatoms according to the presence or absence of raphes (slit-like structures) that allow diatoms to move along firm surfaces. Many centric and some araphid diatoms are planktonic, maintained by turbulence in the limnetic region of a lake, whereas raphid diatoms live on the lake bottom or are attached to objects in the illuminated zone.

It is now possible to reconstruct what happened when the chordates and echinoderms first split from each other. This involves a three-way comparison among: 1) the solute Coleicarpus, which is probably a stem-group dexiothete; 2) the Cincta, which seem to be the least crownward known echinoderms; and 3) the solute Castericystis, which is a stem-group chordate, probably the least crownward known. Counter-torsion of the tail, by which the effects of dexiothetism were nullified in the tail, took place in two phases, firstly in the fore tail and later in the hind tail. Echinoderms and chordates are descended from ancestors that were attached to, or lay on, the sea floor and were therefore much more liable to attack from above than beneath. This probably explains why the main nerve trunk in chordates is dorsal, rather than being ventral as in protostomes.

Echinoderms are a moderately successful phylum today with five classes and about 6,000 living species. They are found in all marine environments from the intertidal zone down to the bottom of deep-sea trenches. Because most echinoderms have a stable calcite skeleton made up of many distinctively-shaped plates, spines, stem and arm segments, and other parts, echinoderms have the potential to produce a long and rich fossil record, and we find this to be true. Although our knowledge of this record is far from complete, some past echinoderm faunas may have approached present-day echinoderm communities in number of coexisting genera and species. Also, many classes of echinoderms are known only from the fossil record, and as many as 12–13 classes may have occurred together at some times in the past. Although they have a wide ecologic range today, most fossil echinoderms are found in rocks representing shallow-water, subtidal, marine environments, either past continental shelves or epicontinental seas.

Polycystine radiolaria that produce siliceous tests are known to range from Cambrian to Holocene. They have proven to be enormously useful in providing age control for siliceous marine sequences of Middle Devonian and younger ages, particularly for cherts and shales that are commonly devoid of other biostratigraphically useful fossils. The utility of radiolarian biostratigraphy became widely recognized in the 1970s and 1980s when it was applied in dating deformed marine siliceous sequences in orogenic belts around the world, most notably in Cordilleran North America and other areas along the Pacific rim (e.g., Jones and Murchey, 1986; Aitchison and Murchey, 1992; Ichikawa et al., 1990).

The purpose of this field trip is to examine sedimentary environments, fauna, and Pleistocene deposits in the northeastern Gulf of California. The coastal area experiences tides of up to 8 meters in amplitude, the Gulf harbors a rich invertebrate fauna, especially molluscs, crustaceans, and echinoderms, and the arid climate of the region makes for a distinctive sedimentary regime. Adjacent fossiliferous Pleistocene deposits provide a glimpse into both ancient habitats and taphonomic processes. In short, the area is an excellent natural laboratory – a laboratory for the study of Recent animal-sediment relations, sedimentary processes, and taphonomy.

Oxygen isotopic analysis of the phosphate in bioapatite has become a standard paleoclimatological tool with results documented in a rapidly expanding literature. Phosphate-based measurements are particularly important for samples where carbonates preservation is suspect (as is the case for many Paleozoic sites). Important analytical and observational advances that have fueled the expansion of phosphate-based studies include: 1) Oxygen isotopic ratios of biogenic apatite can be measured on small enough samples (≥ ~300 μg), quickly enough, cheaply enough, and accurately enough to permit meaningful high resolution paleoclimatic studies of trends through time, along spatial transects, and/or among taxa, 2) biogenic apatite is precipitated in approximate equilibrium with ambient waters and thus records the interplay of temperature and the isotopic composition of the water in which a sample grew, 3) tooth enamel and conodont crown material are quite resistant to diagenetic alteration and are preferred targets for both paleotemperature and paleoecological studies, 4) Paleozoic conodont δ18O records seem to provide robust paleotemperature information on time scales ranging from thousands of years to 100's of millions of years, and generation of increasingly refined paleotemperature records from this diagenetically resistant phase is likely to continue to be a useful field of study, 5) paleoenvironmental variations in δ18O values of seawater have been documented (e.g., differences between glacial and interglacial oceans), but whether and by how much the δ18O value of the hydrosphere may have increased since the Cambrian remains unresolved, and 6) differences in δ18O values among conodont taxa are increasingly well documented and, coupled with the potential to study growth series using ion microprobe techniques, are providing novel perspectives on and important tests of conodont paleoecology.

Holocene sediments are the traditional classroom for learning to recognize the geologic record of different environments. Box cores and shallow trenches display sedimentary stratification and assemblages of organic remains together with their relationship to active surface processes and living organisms. Sedimentologists see the origin of particular bed-forms; paleoecologists learn to match animals to trace fossils, for example; and stratigraphers are reminded that it is not just the sediment surface that is active. Shells, bones, and sediment grains below the surface are still subject to rearrangement. Until this activity has ceased we have not seen what will ultimately be preserved as the mature stratigraphic record of the environment that we have trenched.

To a large extent, a chitinous external cuticle is the distinguishing feature of arthropods (Barnes, 1980). Many of the other features considered characteristic of arthropods, such as growth by molting or the jointed appendages, are either directly or indirectly tied to the possession of the cuticle (Cisne, 1974; Neville, 1975; Grasshoff, 1981).

In recent years, one of the most exciting and important revelations in all of paleontology has been clarification of many of the details surrounding the question of the origin of birds. This has been a persistant enigma for centuries. Today, it is perhaps the hottest topic among challenges before us and it appears closer to a near unanimous opinion than ever before.

Microorganisms (prokaryotes and protists) seldom fossilize, but they form much of the trophic structure in marine pelagic and benthic environments, chiefly as primary producers and secondary consumers. The fossil record of unskeletonized groups is meager or non-existent. Skeletonized groups have excellent records but represent a small portion of the total microbial diversity.

The evolution of trophic structures and roles of microorganisms can be reconstructed broadly for most of geologic history. When life first evolved, it had a trophic structure. The first microbial fossils appear to be benthic mats; these are abundant in the Precambrian but sparse later; body fossils are very rare. The Archean saw pelagic and benthic prokaryotes and possibly protists later on. Proterozoic trophic structures became increasingly complex as protists entered pelagic environments. Benthic assemblages likewise became complex, as prokaryotes and protists formed mats and stromatolites in many environments. At the end of the eon, animals appeared; microbial primary producers and predation on microorganisms and among animals fueled these assemblages. The fundamental trophic structures that developed then persisted with modification into modern times. Phanerozoic ecosystems became very complex as skeletonized animals and protists evolved. Among the important trophic developments in the Phanerozoic history of microorganisms were the early diversification of phytoplankton and siliceous micro-zooplankton (Cambrian), algal endosymbiosis with benthic metazoans (Cambrian to Recent) and rock-forming foraminifera (late Paleozoic to Recent), the radiation of pelagic skeletal primary producers and micro-zooplankton (mid-Mesozoic), and radiations in the deep sea, reefs, and shallow areas (Mesozoic and Cenozoic). Each evolutionary change increased trophic complexity by adding more species at each level, while episodic mass extinctions decreased species diversity and trophic complexity.

Marine trophic structures evolved over immense intervals of geologic time, growing complex and then suffering destruction at major extinction events. The effects of human impact on these structures should be examined, for without them, Earth may change dramatically.

The underlying basis for Mg/Ca paleothermometry is that the amount of magnesium in calcite precipitated from seawater is dependent on temperature. Here we review the state of the art of the Mg/Ca seawater paleotemperature proxy, summarized by the following: 1) Calcite, whether formed abiotically or biologically as foraminifera and ostracode shells, incorporates variable amounts of magnesium into the crystal structure. 2) Uptake of Mg varies positively with temperature. 3) The relationship between temperature and the amount of Mg in calcite has been quantified by experiments on synthetic calcite growth and by culture, core top, and sediment trap experiments using living organisms. 4) The most careful calibrations of the Mg/Ca paleothermometer have been done for planktic foraminifera, then benthic foraminifera; there are species-specific variations in the amount of Mg incorporated into foraminifera shells. 5) The Mg/Ca ratio of calcite from planktic foraminifera in deep-sea cores has been widely used to interpret sea surface temperatures. 6) Measurement of both Mg/Ca and δ18O in planktic foraminifera have been used to calculate δ18O in seawater, and after correction for global ice volume, salinity could be inferred. 7) Mg/Ca from benthic foraminifera have been used to reconstruct deep-sea temperatures and cooling of ~12° over the last 50 million years. 8) One problem with the Mg/Ca seawater temperature proxy is partial dissolution of foraminifer shells, which lowers the Mg/Ca, and leads to an underestimation of ocean temperature. Benthic foraminifers appear to be more resistant to partial dissolution. 9) Past changes in the Mg/Ca ratio of seawater are an important factor in determining the amount of Mg in fossil skeletal calcite, and thus add another variable to the Mg/Ca temperature proxy. All Mg/Ca paleotemperature studies on fossil calcite older than Pleistocene should take into account the Mg/Ca of the seawater from which it precipitated.

Paleosols Crop Out extensively in the Appalachian region of eastern North America, from the Canadian Maritime Provinces southward to the Tennessee-Alabama border along the western side of the Appalachian Orogen (Fig. 1). The paleosols occur primarily in terrigenous clastic redbed deposits ranging in age from Late Ordovician to Early Permian (Mora and Driese, 1999; Driese and Mora, in press), which encompass a time interval characterized by rapid evolution and diversification of terrestrial ecosystems (Table 1). These Appalachian paleosols formed under relatively constant sediment-source area and pedogenic environments (Table 1); thus they share generally uniform physical and chemical properties. As such, they are suitable particularly for investigating evolutionary advances in the gross morphology of plant roots and rhizomes, preserved as traces, and their relationship to physical and chemical features in the paleosols (Table 2). Important changes in plant abundance, rhizome and root systems, and adaptive capabilities are recorded in the paleosols, concurrent with a proxy record of changing environmental conditions. Paleosols represent a still-underutilized record of the terrestrial ecosystem (Retallack, 1990).

Definitions.– Taphonomy is the study of what happens to an organism from the time of its death until it is discovered as a fossil. Whereas paleoecology deals with the interactions between an organism and its environment during life, taphonomy is concerned with post-mortem processes such as disarticulation, predation, transportation, and diagenetic alteration. Biostratinomy (formerly biostratonomy) is the part of taphonomy which covers the history of the organism from death to final burial of the remains. The chemical, physical, and biological processes which affect these remains after burial are dealt with in studies of diagenesis. The relationship of these disciplines is shown in Figure 1.

The paleobotanical literature contains frequent references to paleofloristic regions (often called “floral provinces”) for the Late Paleozoic. Halle (1937) published an early map showing the distribution of four different floral associations in Asia, viz. the Glossopteris Flora, the Angara Flora, the European Permo-Carboniferous Flora and the Cathaysia Flora. Gothan and Weylan (1954) completed this map by adding information from different parts of the world. In 1962 Wagner published a general map showing a Permo-Carboniferous Equatorial Belt separating the northern hemisphere Angara Flora from the southern hemisphere Gondwana Flora. The diagrammatic representation by Meyen (1969) shows the increasing diversifications of these floras with geological time. A later version (Meyen in Chaloner and Meyen, 1973, and in Vakhrameiev, et al., 1978) shows an early differentation into two major units, i.e., the Arcto-Carboniferous Kingdom and the Gondwana Kingdom. The former would be subdivided into the Euramerican and Angara areas, to be distinguished from the Early Carboniferous onwards.

There are three living infraclasses of Mammalia: Prototheria (Monotremes), Metatheria (Marsupials), and Eutheria (Placentals). The egg-laying, poison-spurred and in other ways morphologically reptile-like monotremes now inhabit Australia and New Guinea. Whereas discussion of their past history (Miocene and Pleistocene of Australia; Woodburne and Tedford, 1975) would be a fascinating topic, that group will not be discussed further here.

Taphonomic analysis of fossil remains can provide information on the post-mortem history of the fossils, and may also be useful in interpreting associated sediments. A preliminary survey of the interior surfaces of Recent Chione shells shows that biologic, physical, and chemical agents attacking carbonate substrates in the intertidal environment of Bahia la Choya, Sonora, Mexico, leave behind diagnostic traces of their action.

Shells collected from across the tidal flats and from beach ridge deposits were examined under the SEM and binocular microscope. Tidal flat specimens were dominated by the effects of microboring endoliths. Even recently dead, articulated specimens showed some infestation. Excavation of surfaces by microborers goes through predictable stages, and may therefore be useful for relative “dating” of shells and for estimating burial/sedimentation rates. Beach ridge specimens show a heterogenous array of textures, some inherited from earlier taphonomic episodes, others produced in situ. Textures overprint one another and document transport between habitats.

Similar surface textures should be identifiable in the fossil record and could provide important paleoecologic and sedimentologic information.

Energy and nutrients are the fundamental currencies of ecology and changes in energy and nutrient availability are thought to have played an important role in the long-term development of marine ecosystems. However, meaningfully quantifying when, where, and how such changes have occurred has been a difficult and longstanding problem. Here, some of the various lines of evidence that have been brought to bear on this issue in the past two decades are reviewed, particularly those based on the fossil record of benthic invertebrates. This paper focuses on abundance, body size, and metabolism, three distinct but closely interrelated aspects of ecosystem structure that control (or are controlled by) energy fluxes. Each of these is subject to biases and inherent uncertainties that present significant challenges for making inferences from the fossil record, but when carefully controlling for environmental, taphonomic, and methodological variations there are robust trends that can be discerned above the noise. Integrating these different types of data in a single quantitative framework presents additional complications, but coherent patterns emerge from some such analyses. Accurate quantification of energetic trends in the fossil record is difficult but is a worthwhile goal because of its potential to illuminate the energetic dimension of major diversifications, extinctions, and secular ecological-evolutionary trends and link them more directly to their Earth Systems context.

Knowledge of evolutionary history is based extensively on relatively rare fossils that preserve soft tissues. These fossils record a much greater proportion of anatomy than would be known solely from mineralized remains and provide key data for testing evolutionary hypotheses in deep time. Ironically, however, exceptionally preserved fossils are often among the most contentious because they are difficult to interpret. This is because their morphology has invariably been affected by the processes of decay and diagenesis, meaning that it is often difficult to distinguish preserved biology from artifacts introduced by these processes. Here we describe how a range of analytical techniques can be used to tease apart mineralization that preserves biological structures from unrelated geological mineralization phases. This approach involves using a series of X-ray, ion, electron and laser beam techniques to characterize the texture and chemistry of the different phases so that they can be differentiated in material that is difficult to interpret. This approach is demonstrated using a case study of its application to the study of fossils from the Ediacaran Doushantuo Biota.

Empty molluscan shells retain paleoecological and taphonomic information that may be temporally complex (e.g., successive layers of encrusting organisms) to less complex (e.g., drill holes produced by predatory gastropods at one point in time). Yet, at all levels of complexity, unraveling the ancient “transcripts” requires not only a hopeful paleontologist but also knowledge of the various temporal roles molluscan shells play in community structure.