The central evolutionary, ecological and paleoceanographic questions of the American tropical Neogene relate to how and during what time the Central American Isthmus formed. Geographically, closure was located between the southern edge of the Chortis Block in southern Nicaragua and the Atrato Valley in Colombia. In this region we describe, on the Caribbean side, five Neogene sedimentary basins. They are the Atrato, Chucunaque, Gatun, Bocas del Toro, and Limon Basins. On the Pacific side the Neogene sediments formed as part of the Central American Trench and are well exposed in a series of uplifted blocks on the Nicoya, Osa and Burica Peninsulas. Our analysis allows 1) a construction of the sequence of contrasting sedimentary environments which characterize the different basins, giving a composite geological history of the isthmus for the Late Neogene and 2) identifies the comparable biofacies from the different basins which allow and constrain the evolutionary and ecological questions to be posed concerning the effect of the isthmus as a biogeographic barrier. Temporally, from it's partial emergence in the Middle Miocene, the isthmus shallows by the Early Pliocene (3.5–3.4 Ma) to less than 50 m (Duque-Caro, 1990) when there is a marked differentiation of shelf marine macrobenthic species between the Caribbean and the Pacific. The evidence from reliably dated, large, diverse exchanges of North and South American vertebrates on land constrains the final closure date to not later than 2.8–2.5 Ma (Marshall, 1988). Given that no conclusive evidence for final closure can come exclusively from a study of sedimentary facies, when depths of less than 50 m are involved, the present window of almost 1 Ma, during which final closure must have occurred, will only be narrowed further by the detailed study of very shallow-water fossil clades and complementary molecular data. Present studies indicate that such clades are abundantly preserved.

Clusters of ammonoid embryonic shells have been discovered in several carbonate concretions from a dysoxic, relatively deep water shale (Heebner Shale-Oread Formation) of Virgilian (U. Carboniferous) age near the community of Pomona, Kansas. The concretions from a single outcrop display four distinct units. Unit 1 is the lowest unit and has an evenly laminated fabric with scattered embryonic and juvenile ammonoids, gastropods, and bivalves. The bedding fabric of this unit is interrupted and truncated by a series of pits that form the base of Unit 2, which is a sharply bounded discontinuity. Within the pits there are embryonic ammonoid clusters up to 2.5 cm thick containing as many as 250 individuals per cm3. Some juvenile ammonoids and shell fragments (mostly of ammonoids) are also present. These clusters are capped by Unit 3 which has a gradational boundary with Unit 2. Unit 3 consists in places of a packstone of fossil debris including ammonoid body chamber and phragmocone fragments, three genera of juvenile ammonoids, embryonic ammonoids, and more rarely brachiopods, bivalves, and orthoconic nautiloids. Elsewhere, fossils of Unit 3 are well separated by matrix, which lacks the bedding fabric characteristic of Unit 1. The ammonoids in Unit 3 include mature to sub-mature fragments of Aristoceras and sub-mature phragmocones of Glaphyrites and Shumardites. The brachiopods (articulate and inarticulate) and the bivalves are probably sub-mature or mature. Planktonic bivalves are extremely rare. The number of shell fragments of embryonic and postembryonic ammonoids and other shell fragments decreases upwards from the upper contact of Unit 2. The boundary of Units 3 and 4 is more-or-less gradational; Unit 4 has a sedimentary fabric and faunal content like that observed in Unit 1.

One set of hypotheses to explain the embryo clusters in Unit 2 emphasizes sedimentological processes such as selective transportation and accumulation by currents, turbidity transport and storm deposits. Another set of hypotheses favors biological activities such as reproductive activity and egg-laying. If this second set of hypotheses is correct, these clusters would provide the first documentation of ammonoid reproductive activity and would represent a find as significant in its way as that of the nests of embryo bearing dinosaur eggs.

We review two foundations of statistical inference, the theory of likelihood and the Bayesian paradigm. We begin by applying principles of likelihood to generate point estimators (maximum likelihood estimators) and hypothesis tests (likelihood ratio tests). We then describe the Bayesian approach, focusing on two controversial aspects: the use of prior information and subjective probability. We illustrate these analyses using simple examples.

It is conventional to view the origin and early evolution of life as having taken place beneath an atmosphere devoid of free oxygen. Of primary concern is the fact that experiments designed to produce simple prebiotic compounds as precursor “building-blocks” for life are generally successful only if free oxygen is lacking from the starting mixture of gases. Clearly, life could hardly have evolved in the absence of suitable starting materials. Secondly, organic compounds are thermodynamically susceptible to oxygen and, given enough time, will become oxidized, ultimately to carbon dioxide. A centerpiece of biochemical evidence commonly invoked to support early anoxic conditions is the fact that almost all of the metabolic pathways for respiratory electron transfer in aerobic organisms take place anaerobically. Only the last step in the process requires free oxygen. It is easy to argue that this last step was an evolutionary response to the development of oxygenic conditions and was a later addition to the less energy-efficient pathways found in primitive anaerobes. The assumption in arguments of this type is that the present-day descendants of these early, primitive organisms are using similar biochemical pathways today that they used billions of years ago. For paleobiologists the meagre early Precambrian fossil record is of minimal help and such a uniformitarian approach toward deciphering early evolution is, together with the protein and nucleic acid sequence studies, one of the few methodologies available to go on.

Prosauropods were small to large (maximum lengths approximately 2.5 to 11 m), bipedal to quadupedal, plant-eating dinosaurs with small skulls and elongate necks (Figures 1A, C). They are basal members of the Sauropodomorpha, which include the giant sauropods of the Jurassic and Cretaceous. The Prosauropoda as a group is usually regarded as paraphyletic, because the general trends toward large size, quadrupedality, and herbivory seem to continue into the Sauropoda proper. However, a rigorous phylogenetic analysis of this question has not been made, and some evidence suggests that the prosauropods represent a radiation independent of the lineage leading to the more derived Sauropoda.

Data on extant and fossil corals are analyzed. The characteristics of the organisms are divided into five basic units of data: morphology, ecology, taxonomical relations, stratigraphical, and (paleo-) geographical occurrence. Six data complexes are derived from these units. Their relationships are defined and the database structures designed on the basis of the Entity-Relationship-Model. The data structures are described in detail and advice is given for building up databases. The various opportunities of querying the database and particularly of assessing the data are thoroughly discussed. Data obtainable by transactions on the stratigraphical and (paleo-) geographical distribution of the organisms are considered. Finally, the database on Mesozoic corals compiled by the author is introduced and some preliminary results as well as future projects are presented.

Preparation of fossil specimens has two goals, the exposure of specimens for research, and the final devel-opment of the best specimens for display or photography.

When did arthropods first invade the land? Circumstantial evidence based on trace fossils (Retallack and Feakes, 1987) suggests that large animals, possibly arthropods, may have been present on land and burrowing in soils in the Late Ordovician, but this idea is as yet unsupported by body fossil evidence.

The way we view species distribution patterns, particularly at the level commonly referred to as the “community”, has changed over the past 70 years in biology and, subsequently, in paleontology. Because the degree to which species associations can be interpreted as ecological and evolutionary units depends ultimately on recognition and interpretation of faunal spatial variability, we need to understand the nature of this variability at all levels of resolution before we can adequately address questions of “community” structure and dynamics. While it is possible to recognize spatial variability at several levels, from the distributions of individuals within a species to the overall pattern created by the global biota, we must ask whether these patterns really comprise a hierarchy with natural discontinuities (Fig. 1), or whether it is more realistic to view them as a continuous variability spectrum.

Among the living echinoderms, holothurians are generally regarded as “poor relations” of the other groups. The color and symmetry of sea-stars and the complexity of echinoids usually elicit expressions of admiration from casual observers; the reactions to holothurians usually involves a considerable degree of revulsion. The generally soft-bodied holothurians, with their reduced skeleton and leathery to gelatinous body walls, are consequently less well known than many other echinoderm groups.

Studies of Tertiary plant megafossils typically have aimed at gathering paleoclimatologic and/or biogeographic data. The apparent similarities of Tertiary fossil plants to extant plants have made tempting the use of present plant/climatic relations to infer past climates. Additionally, plant-bearing, nonmarine deposits of Tertiary age are more widespread than older deposits, which allows stratigraphic and geographic distributions of Tertiary plants to be determined with greater accuracy than for older plants.

Methods of interpretation of living habits of ancient brachiopods.–The most obvious means to interpret life habits of ancient brachiopods is by analogy with living ones. Increased knowledge of the living ones, however, is revealing progressively more pitfalls in the path of using their examples to arrive at easy conclusions regarding the ancient ones. As the analogies are applied to ever more ancient forms, the similarities decrease and the interpretations become increasingly tenuous. Even the supposed “safe” interpretations of ancient terebratulids and rhynchonellids on the basis of analogy with their living relatives are being challenged by new research. Formerly, presence of a pedicle foramen was considered prima facie evidence that the shell lived attached to a substrate of some kind, but this can no longer be assumed, and further evidence for attachment must be sought.

Fossil crinoid studies have been extensively summarized in the most recent volumes on echinoderms in the Treatise on Invertebrate Paleontology (Moore and Teichert, 1978), less than 2 years ago. It would be presumptuous of us to try to provide a summary of the three Treatise volumes on crinoids in 15 typescript pages.

Character independence is an important assumption in parsimony-based phylogenetic analysis. For taxa with extant representatives, the analysis of within-species covariation of quantitative characters provides a basis for assessing character independence. One promising approach is to use mean species scores on factors of within-species covariation as phylogenetic characters, but the use of common morphometric factor models leads to problems with either the independence or the interpretability of such characters. Principal components and principal factors, whether rotated or not, may be constrained to be orthogonal but may be difficult to interpret since the effects of each factor are spread over all variables. In Wright-style factor analysis the restriction of secondary factors to subsets of variables facilitates their interpretation, but the factors may be highly correlated.

An alternative approach is to adopt a hierarchical factor model in which correlated first-order factors are restricted to subsets of the variables. Size is modelled as a second-order factor inducing correlation of the primary factors, in contrast to the common morphometric procedure of attempting to partial out size in the first stage of analysis. The size-independent components of the primary factors provide shape characters which are interpretable as the deviations of regional growth from their predictions based on size. Hierarchical factor models have been widely used in psychometric studies since their introduction by Thurstone in the 1930's, but have been little used in morphometric analyses.

The hierarchical model is applied to the covariances of interlandmark trusses measured on skulls of extant canids using a video-based stereophotogrammetric system. Preliminary results indicate that the canid skull may be partitioned into discrete regions of relatively independent local growth.

Preliminary evidence supports a series of predictions and speculations that derive from the hypothesis of evolutionary escalation (Red Queen). If biotic interactions have intensified over geologic time, then:

(1) Energy budgets of individuals have increased. This involves both sides of the equation Consumption = Growth + Reproduction + Respiration (includes locomotion & feeding) + Feces + Excreta. Thus living representatives of formerly successful taxa have lower energy budgets than ecologically similar taxa that were successful later, e.g., reptiles vs. mammals, Sphenodon vs. other reptiles, brachiopods vs. bivalves, Nautilus vs. coeleoids, gymnosperms vs. angiosperms.

(2) The price of success (cals. per reproducing offspring) has increased. Thus Red Queen evolution leads to energetic inefficiency.

(3) Energetic escalation is fueled by increasing plant biomass and turnover, especially on land (angiosperms, including N-fixers such as legumes). The enlarged trophic base pemits diversification without reduction of niche size. Evolution of marine benthos (our primary record of evolution) may be fueled directly by fixed C or indirectly by fixed N (shelf waters are normally N-limited), both increasingly supplied from land as a result of steady state mortality (deciduousness, self-thinning, short life-cycles) or disturbance mortality (fire, wind) of bigger standing crops. The Mesozoic origin of new phytoplankton such as diatoms may be a consequence of terrestrial angiosperms. In turn, diatoms produce lipid, a more energy-dense food than the carbohydrate produced by other phytoplankton. Increased skeletonization of Mesozoic phytoplankton may have diluted the food of Paleozoic-style suspension-feeders, especially brachiopods. Brachiopods have blind guts, which they readily stuff with non-nutritive particles and tight (efficient) energy budgets that might not sustain increased feeding costs.

4) Archaic organisms survive in oligotrophic refugia that exclude more recent, high-energy enemies. Marine animals move to deeper water (explaining offshore migration over the Phanerozoic, e.g., Latimeria, Nautilus, Zoophycos.). Other refugia are high latitudes, caves, or dark fiords. Living articulate brachiopods flourish in all of these except the fluvial-influenced Arctic Ocean. Refugia for archaic flora restrict light, water, or N (high latitudes and elevations, forest floor, poor soil).

5) Survival in oligotrophic refugia selects for lower energy budgets, including reduction of respiring tissue, so Cope's Rule is reversed (thecideid brachiopods, lycopods, sphenopsids).

The trace fossil Oldhamia reflects systematic strip mining of an infaunal, worm-like sediment feeder. It is known from many parts of the world in Cambrian complexes, whose flysch-like and accreted character suggests deposition on a deep continental slope. In similar rocks of the North Carolina Slate Belt. Oldhamia is associated with rare specimens of the Ediacara-type body fossil Pteridinium, as well as tool marks of a problematic stiff organism reminiscent of graptolite stipes (Vendospica).

This occurrence (1) extends the stratigraphic range of Oldhamia into the Late Proterozoic. It also reminds us that, by that time, worm-like, endobenthic bilaterians (2) had become behaviorally specialized and (3) had colonized shelf and deep-sea bottoms well before the Cambrian evolutionary explosion. (4) Since bioturbators were small and did burrow strictly along bedding planes, their mixing effect was as yet negligible. (5) The new tool-mark fossils tell us that complex, organic-walled and perhaps colonial organisms were around in addition to sand-corals (Psammocorallia), possibly sponges and the probably plasmodial Vendobionta.

The present state of knowledge permits only the grossest assessment of nutritional physiology of living brachiopods since most of the knowledge available on brachiopods is not addressed from this aspect and when it is, much of the information is derived from studies made without the use of modern investigative methods. Additionally, of the few studies that have been made on the physiology of the brachiopod digestive system, most have been on the genus Lingula. Unfortunately, this is one of only 2 genera that occupy an infaunal habitat, all other living genera are epifaunal forms (Table 1). The geographic distribution, habitat preference, and digestive modifications suggest that there are some differences in dietary characteristics between the infaunal and epifaunal brachiopods. With these limitations in mind, studies on physiology of digestive systems in other phyla will be used for comparison.

The Study of Cenozoic planktonic foraminifera has benefited in the last 1–1/2 decades by Deep Sea Drilling retrieval of many cored sections from the major ocean basins of the world. The stratigraphy of planktonic foraminiferal species in these ocean basins has provided important data on evolutionary lineages of species and biostratigraphic utility of species. The geographic coverage of the oceans has given a clearer picture of the biogeography of species and of past oceanographic conditions. It has become clear that the evolution of planktonic foraminifera was controlled by oceanographic and climatic events related to the redistribution of land and sea. The purpose of this presentation is to summarize the major patterns of the paleobiogeography of planktonic foraminifera during the Cenozoic.