Plaster of Paris is a general term for gypsum plasters and gypsum cements. Plaster, which has been in widespread use for producing casts of fossils since the Nineteenth Century (e.g., Green, 1832; Ward, 1866), is easily used for making rigid, long-lasting, and inexpensive casts of study specimens, and for making field casts from natural molds. Good general descriptions of the use of plaster are given in Clarke (1938) and Rich (1947), as well as in many recent books on sculpture (e.g., Miller, 1971; Chaney and Skee, 1973; Andrews, 1983), and in various brochures distributed by manufacturers (e.g., United States Gypsum Company, 1987a, 1987b). Using plaster for casting paleontological specimens was previously discussed in works by Quinn (1940), Keyes (1959), Heintz (1963), Rigby and Clark (1965), Rixon (1976), and Chase (1979).

In the mid-twentieth century much of the impetus for paleoecological research was from the need for the fossil record to provide paleoenvironmental information. At that time earth scientists trying to understand the environmental context in which sedimentary rocks were deposited began extensive utilization of fossil components and sedimentary structures to make their interpretations. Towards this end, paleontologists and biologists catalogued the environmental preferences and depth distributions of modern organisms, and these modern distributions have been utilized in paleoenvironmental reconstructions by means of taxonomic uniformitarianism. Physical sedimentary structures have also been studied extensively in modern environments and laboratory simulations so that their occurrence in rocks can provide detailed information on ancient environments.

K.S. Thomson, 1985: p. 73

R.T. Bakker, 1986: p. 462

It is a now oft-repeated statement that we are in the Second Golden Age of dinosaur studies. This may at first seem to be yet another overstatement by dinosaur fanatics; in fact, it is substantiated on a number of fronts. Research activity is certainly at an all-time high, with resident dinosaur researchers on every continent (except Antarctica) and dinosaurs known from every continent (including Antarctica). This activity has resulted in a spate of discoveries, including not only new genera and species, but entirely new types of dinosaurs, such as the segnosaurs. Well-known groups are producing surprises, such as armored sauropods and sauropods bearing tail clubs. Good specimens of previously named genera are revealing unsuspected structural features that almost defy explanation, as in the skull of Oviraptor. However, dinosaur studies extend far beyond the traditional emphasis on dinosaur morphology, and encompass paleobiogeography, paleoecology, taphonomy, physiology, tracks, eggs, histology, and extinction, among others. In some cases, several of these studies can be applied to a single taxon or locality to give us a fairly detailed understanding of the paleobiology of some species.

Statistical methods can assist the paleoecologist in evaluating tentative conclusions and hypotheses that are obtained by more traditional means of analysis. They may also enable the paleoecologist to obtain more information from a set of data than she might otherwise. The purpose of this presentation is to introduce a number of statistical methods that are useful in the analysis of some specific paleoecological problems.

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Mammalia constitute one of the five major classes of vertebrates (the others being Pisces, Amphibia, Reptilia, and Aves). There are, at latest count, some 4,170 species of mammals living today, classified in about 1010 genera, 130–140 families, and 18 orders (Corbet and Hill, 1980; Honacki et al., 1982). In addition, sixteen orders and uncounted genera and species of mammals are known to be extinct (see synoptic classification in Table 1). While most living mammals are terrestrial like their Mesozoic ancestors, one large progressive group has invaded the air (bats, represented by about 150 living genera and 920 species). Two other smaller groups are fully aquatic (whales, including some 40 genera and 80 species; and sirenians, 3 genera and 5 species). Mammals occupy all of the continents, and all of the larger oceanic islands. Faunal diversity is greatest in lowland tropical forests, woodlands, and savannas, decreasing rapidly at high elevations and latitudes.

Controversy concerning the affinity of the stromatoporoids is not new; it began over 100 years ago with the first systematic studies of the group. Rosen's (1867) opinion was that these fossils were allied to the sponges. Nicholson and Murie (1878) agreed. Solomko (1885) introduced some of the arguments still used by the advocates of the poriferan affinity of the stromatoporoids such as the recognition of the astrorhizae as excurrent canal systems. H.A. Nicholson who had at first supported the hypothesis of sponge affinity became convinced that the closest living representatives were to be found in the hydrozoans. He compared the skeletons of the stromatoporoids like Actinostroma to the modern hydrozoan Hydractinia and the skeleton of amalgamate genera like Stromatopora to that of Millepora. Nicholson's monograph of British stromatoporoids (1886–92) and the papers he published in the Annals and Magazine of Natural History to accompany his revision of the group form the basis of all later work and hence his views on the affinity of stromatoporoids had immense influence.

The Subphylum Homalozoa is divided into four classes, which while having similar morphological features, are at best distantly related. All classes exhibit flattened thecae, are bilateral to relatively asymmetrical and apparently were surface detritus feeders or low level suspension feeders. Many homalozoans display thick marginal plates with smaller central plates on dorsal and ventral surfaces, possibly to augment gut and/or cloacal pumping.

When sponges were well-behaved, a calcareous skeleton was sufficient for assignment to the Class Calcarea. Since the discovery that some sponges secrete both siliceous spicules and a massive calcareous skeleton (Class Sclerospongia Hartman and Goreau, 1970) and more recently, the discovery of an apparent living Sphinctozoan with an aspicular calcareous skeleton and soft parts like those of a demosponge (Vacelet, 1977b) the picture has become more clouded. The groups to be discussed here originally included all the known sponges with massive calcareous material in the skeleton. They were named Pharetrones by Zittel (1878) who emphasized the skeleton of anastomosing fibers, containing, so he thought, spicules packed side-by-side like arrows in a quiver (pharetra is Greek for “quiver”). Steinmann (1882) noted that in some of the genera included by Zittel as well as in new forms which he described, the skeleton was sheet-like and outlined a series of hollow chambers. Steinmann set apart the chambered types as a subgroup Sphinctozoa(=“constricted animals”) and the fibrous types as the subgroup Inozoa(=“fiber animals”). Steinmann also pointed out that the skeleton of the Sphinctozoa was aspicular and spherulitic. Zittel had illustrated the spherulites but considered them diagenetic. Steinmann, however, observed that the spherulites were bored by endolithic algae or fungi, and were therefore probably original. He also noted that the spicules in some Inozoa were sinuous and unlike typical sponge spicules, and indeed considered the pharetronids not to be sponges at all. Hinde (1884) and others soon demonstrated that the fibers of many pharetronids, as well as the external cortical layer (including that of the sphinctozoan Tremacystia) contained typical triradiates of the Class Calcarea. The discovery of the first living pharetronids (Doederlein, 1892, Kirkpatrick, 1900, 1908) with soft-parts and flesh-spicules typical of the Calcarea, seemed to settle the matter. Rauff (1913) introduced the useful term sclerosome for the non-spicular material of the skeleton, which might range from simple cement between spicules to the entire skeleton. It is this material that recent studies by Wendt (1979, 1980), Cuif and others (1979), and Jones (1979) have shown to be quite heterogeneous and variable. We will now look at the morphology and fossil history of the Inozoa and Sphinctozoa without any commitment as to the biological unity of each group.

Assessment of changes in terrestrial ecosystems since Cretaceous time, until recently, has had to rely on paleobotany (including paleopalynology) and vertebrate paleontology to provide data for analysis. Insects contribute a major portion of the terrestrial diversity in any ecosystem, but their fossil record and state of preservation had discouraged paleoecological study beyond the Pleistocene. With the discovery of prolific Upper Cretaceous amber deposits in Russia and Canada, and the investigation of Tertiary amber deposits from the Baltic, the Dominican Republic, Mexico and the USA, the prospect of clarifying changes in insect diversity and ecology over time becomes real. Methods are reported which allow the description of species richness and relative abundance of arthropod taxa from an Upper Cretaceous (Campanian: 75 MYA) amber deposit in Alberta, Canada. Diversity and abundance are described at the Order level for hexapods, and for the Acarina and Araneae. Taxa present, in order of abundance, are Homoptera (66 specimens/kg of amber), Diptera (28/kg), Acarina (21/kg), Hymenoptera (13/kg), Araneae (12/kg), Psocoptera (4/kg), Coleoptera (2/kg), Blattodea (1/kg), Thysanoptera (1/kg), Trichoptera (0.6/kg). Other orders present are Lepidoptera, Collembola, Dermaptera, Mantodea, and Ephemeroptera. In total, of 35 identified families, 8 are extinct. There are about 20 genera identified, of which only 1 is extant. All identified species are extinct. Estimated species richness is about 100 species of arthropods. In comparison, virtually all Families reported from Baltic amber (Oligocene) are still extant, as are the majority of genera. Morphology and feeding structures are well within the variation seen in modern insects. This suggests that throughout the Tertiary, Entomologists would feel quite at home with the insect fauna, and during the Upper Cretaceous, they would have little difficulty identifying insects at least to the family level. It is hypothesized that the taxonomic structure of modern insect communities was well established before the end of the Cretaceous, and that the structure and interrelationships of insect guilds were also very similar to those of today.

The Aporrhaidae is an important family of marine gastropods whose members are characterized by an expanded apertural lip. A phylogenetic analysis of this clade confirmed its monophyly although a few of the constituent genera, as presently defined, are polyphyletic. Stage-level diversity data for the Northern Hemisphere genera gathered through fieldwork, visits to museum collections and from the literature indicate an initial radiation of this clade during the middle Jurassic. This radiation produced 9 genera by the end of Callovian. Similar levels of generic diversity were maintained throughout latest Jurassic and the earliest Cretaceous. During the Jurassic the aporrhaids appear to have been geographically restricted to Europe and Africa. However, given the paucity of Jurassic marine sediments on most continents, this distribution is probably biased although absences in Japan and North America are probably genuine. The later part of the early Cretaceous history of this group is characterized by a major faunal turnover which resulted in the extinction of over 70% of the Jurassic genera and the evolution of at least 10 new Cretaceous genera. The group reached its highest diversity during the Albian, followed by a slight decline during the Cenomanian. This diversity peak is at least partially attributable to the exceptional quality of preservation during the Albian which is unsurpassed in any Jurassic or Cretaceous stages except the Maastrichtian. The average diversity for the rest of the Cretaceous stages remained around 12 genera and by late Cretaceous the group achieved a global geographic distribution. The aporrhaids suffered a severe setback during the Maastrichtian when at least 75% of the genera went extinct. The stratigraphic data presently available does not provide enough resolution to determine whether this extinction coincided precisely with the K-T event. At the generic level this extinction does not seem to exhibit any selectivity based on geographic range. Of the three end-Cretaceous survivors, Drepanocheilus and Arrhoges were widespread geographically while the third, Aporrhais had a restricted distribution. Similarly the taxa that perished included both endemic genera and widespread ones like Quadrinervus. The Cenozoic history of the clade is characterized by very low levels of generic diversity and restricted geographic distribution with only two extant genera.

From a macroevolutionary perspective, the late Neocomian turnover as well as the Maastrichtian extinction of aporrhaid genera are particularly interesting. The first event gave rise to a number of distinctive morphologies and coincided with the radiation of various groups of durophagous predators such as decapod crustaceans as well as with the rise of the carnivorous gastropods. The nature and timing of this change suggests that it could be a part of the broader Cretaceous faunal reorganization commonly known as the “Mesozoic marine revolution” (Vermeij, 1977). The end-Cretaceous event is interesting for its magnitude as well as its consequences. The aporrhaids maintained a remarkably stable generic diversity level from mid Jurassic to late Cretaceous, but never recovered from the Maastrichtian extinction. This pattern is in direct contrast to that exhibited by the sister group of Aporrhaidae, the Strombidae. The strombids exhibit extremely low generic diversity and restricted geographic distribution during the Cretaceous but radiated rapidly during the early Cenozoic. Such reciprocal diversity trends, combined with close phylogenetic relationship and functional similarity of the two groups as well as the presence of morphologic convergence, suggests extinction induced replacement and seems to be consistent with models proposed by, among others, Hallam (1987) and Rosenzweig & McCord (1991).

Downcore changes in carbonate content can be produced by varying rates of taphonomy, physical and biological reworking or changes in rates of carbonate addition. Only the latter can be used to investigate changes in carbonate productivity in the living community. Only the latter indicate unequivocal changes in community structure. The stratigraphic, taphonomic and biologic records from two cores in Copano Bay, Texas were analyzed to determine (1) whether variations in shell content with depth were caused by variations in carbonate preservation, carbonate production or sedimentation rate and (2) the extent to which characteristics of fossil assemblages such as species composition, numerical abundance, biomass, and trophic and habitat structure, identified similar or different trends. Below the top few cm of the sedimentary column, variations in carbonate content with depth could be attributed to variations in carbonate production. Most biological attributes varied similarly with depth and, hence, time on both long (≥ 100 yr) and short (~ 10 yr) temporal scales. These variations could not be explained by any taphonomic process, sediment reworking and burial, or sedimentation rate. Despite a vigorous taphonomic milieu, explaining the shell content of Copano Bay sediments requires the preservation of nearly all carbonate produced. Doing so requires the preservation of most of the relatively large-shelled biota (large species and adults) which retain important evidence of changes in the community's history in this area. The results reemphasize the importance of large individuals and biomass in paleontologic reconstruction and suggest that changes in community productivity, which in paleontologic usage, must be carbonate productivity, are preserved in the fossil record in some assemblages. Taphofacies analyses might be used to identify such assemblages.

Cells of Emiliania huxleyi are surrounded by ‘coccoliths', minute, elegant scales of calcium carbonate. In all the oceans, particularly at mid-latitudes, this species forms gigantic blooms, readily visualized by satellite imagery. Coccolith-bearing organisms, of which E. huxleyi is by far the most abundant representative, are the major contributors to the ocean floor limestone sediments, and this in turn is the largest long-term sink of inorganic carbon on earth. In addition, E. huxleyi blooms emit vast amounts of dimethyl-sulphide (DMS), a gas which, on oxidation, is a dominant source of cloud nuclei. The profusion of E. huxleyi and its intimate involvement with the global biogeochemical cycles of both carbon and sulphur make it a key component of the greenhouse effect (CO2), natural acid rain and albedo regulation.

E. huxleyi blooms are often almost monospecific. They can be visualized by satellite imagery and leave highly characteristic skeletal and macromolecular markers which accumulate on the deep-sea floor as a long-term record of their history. The organism is easily cultured in the laboratory and molecular genetical, biochemical and physiological studies are underway.

We focus on Emiliania huxleyi as a model organism to study interactions between oceanic plankton and climate. Benefits of this approach are: (1) to highlight the idiosyncratic non-linear character of these interactions; (2) to reveal the intimate coupling of the oceanic carbon cycle and DMS productivity; and (3) to allow an integrated modelling and experimental approach, integrating multi-disciplinary studies that range from the global down to the macromolecular level and through geological time. E. huxleyi coccoliths and specific biomarkers preserved in the geological archive not only provide information on the distribution of this organism in the geological past. The connection with extensive neontological research offers a unique opportunity to reconstruct the development of the entire E. huxleyi system, including its multifarious climatic interactions, through geological time.

The ‘Global Emiliania Modeling Initiative’ (GEM), started in 1990, is a European research program intended to investigate and model the Emiliania huxleyi system.