Since dinosaur fossils are not numerous enough for statistics, the idea of studying dinosaurs at all has been questioned. Teeth of Judith River tyrannosaurs (late Cretaceous of south-central Alberta, Canada) are sufficiently numerous and rich in anatomical structures for statistical analysis: 1. No difference was found between widths of serrations of anterior and posterior rows (Mann-Whitney U test, two-tailed; n = 24 tooth fragments: p> .05; anterior and posterior x = 0.4 mm): 2. Reversals in uniform trends in serration width within each serration row were more numerous for the anterior (reversals = 51; non-reversals = 74) than for the posterior (reversals = 45; non-reversals = 135) serration rows (χ2 (2×2) = 7.82; d.f. = 1; p< .01); 3. Serrations of the anterior row are more steeply angled toward the point of the tooth than are those of the posterior row (Mann-Whitney U test, two-tailed, n = 21 tooth fragments; p< .01; anterior x̄ = 8.9°; posterior x̄ = 5.0°): 4. Small teeth (mean length = 9.8mm) show less tendency to be scratched than large ones (mean length = 25.0mm) (t(d.f. = 234) = 4.64; p< .01); 5. Inter-serrational slots of posterior row require less force (x̄ = 0.14 newton) to cut standard nylon filament (diameter = 0.04mm; tensile strength = 0.42 newton) than did slots of the anterior row (x̄ = 0.24 newton; Mann-Whitney U test, two-tailed; p< .05; n = 17 fragments); 6. There is a significant difference between edge radii r (expressed in microns μ) of serrations of three classes of tyrannosaur teeth: unerupted/partially erupted (x̄ = 78.2μ), vs. fully erupted but still attached to bone (x̄ = 94.7μ), vs. shed (x̄ = 139.3μ) teeth (two factor analysis of variance, F(2,173) = 10.86; p< .05). Teeth of Judith River tyrannosaurs possess numerous structures, both interior and exterior (see figure) whose geometry differs markedly from that of, e.g., troodon teeth (which may possess a radix, but no other differentiated internal structures), or thecodont teeth (which possess a peak of interior enamel intruding into each denticle and tilted toward the point of the tooth). Statistical anatomy of teeth may offer a rich source of information for studying taxonomy, evolution, and migration of tyrannosaurs.

Flume experiments with models of Mid-Paleozoic atrypids, orthids, rhynchonellids, and spiriferids indicate that the central fold functions efficiently to separate lateral-margin incurrents from the anterior-medial margin excurrent in five of nine possible life orientations of the shell relative to the current direction and substrate. Anterior-medial incurrents and lateral excurrents are effectively separated in four of the nine orientations used with models of spiriferids and atrypids, but nonpediculate brachiopods drawing in water anterior-medially could not take advantage of reversing tidal currents to feed. The risk of refiltration of medial excurrent water is reduced with increasing relief of the central fold above the commissural plane. Downcurrent turbulance increases with increasing relief of the central fold. Eddies with a large radius of curvature are generated by large chevron-shaped central folds at low current velocities (5 cm/sec) and boomerang against the downcurrent lateral margin of models. Flume experiments on models also reveal that a well-developed sinus accelerated erosion of the supporting sediment around the weight-bearing posterior of the valves. Shells with high relief in the sinus destabilized comparatively quickly from valves-erect orientations when subjected to moderate current velocities (25 cm/sec).

Morphospace (ternary) diagrams of sinus shape for Late Ordovician (Caradocian) through Devonian (Famennian) genera show the realized field among the potential morphotypic extremes, namely, 1) rectimarginate (no fold), 2) isoclinal, chevron-shaped, and 3) M-shaped anterior commissural outlines. Morphospace plots through successive stages suggest centripetal selection for taxa with moderately developed folds in the atrypids and spiriferids, with occasional evolution of “outlier” genera with chevron-shaped central folds. Orthids display progressive loss of rectimarginate genera through the Devonian. Weak directional selection is suggested by the succcessive stage-level plots of the rhynchonellid genera which expanded toward the extremes of chevron- and M-shaped central folds in potential morphospace during the Devonian.

Although trophic position or level is one of the most basic aspects of a benthic marine species' ecology, its evolutionary significance remains obscure. Gastropods offer a suitable model for examining the relationship between trophic level and evolution since they exhibit a wide variety of trophic strategies and their mode of life is often reflected in their shell form. We examined 196 genera of Paleozoic gastropods (≈ 1/3 of known genera) for which first appearance and last appearance could be specified to stage level and for which trophic strategy could be inferred with a reasonable degree of confidence. We classified these genera into four trophic categories on the basis of shell characters relating to locomotion and clamping. These trophic categories are: Suspension feeders, Grazers on firm substrata, Soft substrate Grazers/Detritivores, and Carnivores. Suspension feeders are the most unambiguously recognizable category, marked by clear indicators of a sessile mode of life such as a radial apertures and planispiral shell forms. Our central observation from these data is that suspension feeders have shorter generic longevities than the other three trophic groups. This pattern is robust to a variety of methods of analysis. The mean generic longevity of the suspension feeders is 15 MY less than the other trophic categories. Cumulative frequency of genera within trophic categories versus log duration shows suspension feeders to be statisticaly significantly shorter lived than the other three trophic categories. The other three categories are not distinguishable. This pattern is unchanged by the removal of taxa dying out at mass extinctions. Suspension feeders have lower origination rates and higher extinction rates than the other trophic classes. This is not a taxonomic artifact produced by ornamentation and the number of characters available. This background pattern is also present in the end Ordovician and Late Devonian mass extinctions. Suspension feeders loose about half their genera in these extinctions, the two classes of grazers loose about 1/3 of their genera, and the carnivores suffer almost no extinctions. Suspension feeding appears to carry a significant evolutionary detriment in both mass extinctions and background times. This may be reflected in the change in trophic distribution of gastropods from the Ordovician to the Recent. The end Permian extinction shows a different pattern of selectivity; detritivores suffer the least.

The late Cenozoic history of mollusks in the tropical and subtropical Western Atlantic has traditionally been viewed as one of decreasing species richness via a series of more or less discrete extinction episodes, from a Mio-Pliocene peak to the depauperate (relative to the Eastern Pacific) fauna of today. These extinction episodes have been interpreted by some authors as responses to climatic deterioration, especially climatic cooling associated with northern hemisphere glaciation.

Two new species-level compilations of gastropods suggest, however, that this traditional scenario may be oversimplified.

1) A new (but still preliminary) compilation of species from the Late Pliocene “Pinecrest Sand” of southern Florida contains 365 species. This compilation is based mainly on specimens > 5mm in size taken from bulk samples collected in quarries near Sarasota and held in the collections of the Florida Museum of Natural History; when smaller specimens are considered, and systematic analysis of larger forms from this and other localities is complete, it is likely that this number will increase significantly. The Pinecrest has been systematically neglected; although our count is preliminary, it represents the most complete and well-documented compilation available for this spectacular and highly diverse fauna.

This number for the Pinecrest compares with 479 species of gastropods in the overlying Late Pliocene-Early Pleistocene Caloosahatchee “Formation” (data of Campbell et al., 1975). 178 gastropod species are in common between the two units, yielding an extinction level of 51.2%. 301 (62.8%) of the Caloosahatchee gastropod species are not present in the Pinecrest.

Stanley (1986) listed 211 species of bivalves in the Pinecrest and 150 in the Calooshatchee, with 110 in common, giving an extinction level of 47.9%. 40 (26.7%) of the Caloosahatchee bivalve species are not present in the Pinecrest.

2) A new compilation of all described Recent shelled gastropods in the Western Atlantic (Cape Hatteras to Rio de Janeiro) contains 2800 species (2418 of which were described before 1972), compared to the 2360 species listed by Keen (1971) for the Recent Eastern Pacific. These two lists compare similar size and depth ranges, and indicate that the Western Atlantic gastropod fauna is not less species-rich than the Eastern Pacific gastropod fauna.

In addition, a growing body of evidence from other studies (ostracodes, foraminifera, isotopic analyses) indicates that the Late Pliocene was not a time of marked climatic cooling, at least not in the Western Atlantic. Still other studies (e.g., of the biogeography of turritelline gastropods, isotopic analyses on both sides of the Central American Isthmus, paleoceanographic modelling) suggest that the most significant environmental changes at this time may have been associated with changes in nutrient levels.

Taken together, these very preliminary results suggest a more complex history for the Western Atlantic mollusk fauna than previously envisioned. If the Plio-Pleistocene was a time of significant turnover but not significant diversity decline, and gastropods of the Recent Western Atlantic are not less diverse than their Eastern Pacific counterparts, then the patterns to be explained must be reexamined. Late Cenozoic extinction may have been significant in the Western Atlantic, but it may have been accompanied by high levels of diversification.

In any case, those faunal changes that did occur at this time may have been caused as much or more by changes in nutrient levels as in temperature.

Multivariate analysis of paleobiological species lists is made difficult by taphonomic, monographic, collection, and sample-size bias. These problems can be partially surmounted by determining which pairs of taxa have overlapping (conjunct) or non-overlapping (disjunct) distributions. Two taxa are conjunct if they are found together in at least one species list. The conjunction data type has two important properties that strongly contrast with other measures of taxonomic association: 1) the set of known and actual conjunctions converge on each other as more and more conjunctions are demonstrated by new species lists; and 2) the fact of conjunction between two species is independent of particular sampling regimes.

While an apparent conjunction is necessarily real, apparent disjunctions can result from sampling bias. Methods that use conjunction data should therefore attempt to “explain” a pattern of disjunction. One approach is to order taxonomic “first” and “last” appearance events to form a hypothetical age-range zonation. Disjunction is accounted for when age-ranges do not overlap, and the most parsimonious zonation minimizes implied conjunction. An appropriate algorithm is as follows: 1) compute a conjunction matrix; 2) perform a correspondence analysis on this matrix; 3) multiply the resulting taxonomic scores by the original taxon-by-species list matrix to produce a set of species list scores; 4) arrange the lists in the order of their scores; and 5) deduce an appearance event sequence from the species list sequence. In some cases a “zonation” can best be interpreted as a biogeographic or paleoecological gradient.

A conjunction analysis of 1030 mammalian species lists from the late Eocene - Pleistocene of North America was performed. Radiometric dates are correlated strongly with the positions of species lists in the sequence. Because they are independently derived, the radiometric and event time scales are truly cross-confirmatory. Calibration of the event sequence using 54 independent dates was carried out, and separate diversity curves for species and lineages were computed directly from the event sequence. The major features of the curves are 1) a moderate Chadronian-Orellan (Eocene-Oligocene) boundary extinction; 2) middle Miocene diversity peak; and 3) a major Mio-Pliocene boundary mass extinction. Finally, the North American Land-Mammal “Ages” (NALMAs) were redefined on the basis of the event sequence. Boundaries within the sequence were optimized to prevent apparently disjunct taxa from ranging into the same time unit. The most important result is that the “Arikareean” consists of two easily distinguished and lengthy NALMAs separated at the Oligo-Miocene boundary. The two new NALMAs will be named and defined in a later paper. Additionally, the “early Hemingfordian” is placed in the “late Arikareean”; the “early Barstovian” is transferred to the Hemingfordian; and the “late late Barstovian” is unquestionably early Clarendonian. Most of the quantitatively defined NALMA and “subage” boundaries coincide with small extinction episodes.

A similar, more preliminary analysis of the European Miocene generated biochrons that match most of Mein's MN zones. Most of the revised Mein zone boundaries coincide precisely with the NALMA boundaries. This could indicate that global factors (climate change, asteroid impacts, etc.) are responsible for the majority of the minor mammalian extinction events that are spaced at 1 – 2 m.y. intervals, and, therefore, for a significant fraction of species-level mammalian extinctions.

Neogene deposits of the northern Dominican Republic contain a diverse fossil assemblage that is especially rich in corals and mollusks. To see if faunal change was concordant or discordant within and among taxa and decipher factors controlling distributions, we compared distributions of coral communities, the gastropod families Strombidae and Marginellidae, and the bivalve family Corbulidae. We also incorporated published ranges for the Cardiidae (Vokes, 1989), Cancellariidae (Jung and Petit, 1990), and the columbellid genus Strombina (Jung, 1986).

First and last appearances of individual mollusk species were diachronous among sections. Within the sections, however, first and last appearances of mollusk species tended to coincide. Concordance of species ranges could be caused by unconformities or faults, be an artifact of sampling, or indicate similar responses by species to environmental changes. Neither stratigraphic gaps nor faults appear to correspond to concordant first or last appearances. Although the absence of mollusk taxa generally corresponds to less intense sampling, sampling intensity is highly correlated with the presence of macrofossils and therefore, taxa absence is probably real. First and last appearances do coincide with paleoenvironmental changes such as rapid deepening, introduction of marine conditions, increased intensity of erosional bottom currents, and changes from reefal to sand flat facies.

Comparisons among taxa also helped elucidate other distributions patterns. For instance, comparing coral communities to strombid ranges showed that strombid diversity increased in grass flats (inhabited by free living corals) and reefal deposits, indicating similar ecologic preferences to many modern strombid species. Using the coral fauna to distinguish a grass flat community from other shallow marine facies also helped explain corbulid abundances as environmentally induced, with lower numbers in grass flat deposits.

Simultaneous comparison of species distributions within diverse taxa can help explain the nature of species occurrences. For several mollusk taxa from the Neogene of the Dominican Republic, the general correspondence in distribution patterns across taxa indicates that paleoenvironmental conditions were controlling species distributions.

The excellent preservation of calcareous invertebrates and phosphatic vertebrates in the Lower Oxford Clay provides a good opportunity for paleooceanographic reconstruction based on stable isotopic abundances. We present here our initial results and interpretations on carbon and oxygen isotopic analyses on fossils of different depth habitats. Benthic fossils include epifaunal oysters and infaunal nuculacean bivalves. We also analyzed “pendant” bivalves whose depth habitat is uncertain. Fossil nekton are represented by ammonites and belemnites. Organisms that inhabited the uppermost part of the water column are represented by marine reptiles, such as icthyosaurs and plesiosaurs, and probable pelagic fish.

The oxygen isotopic compositions of calcareous benthos and nekton overlap substantially (δ180 = −2 to +1 permil vs. PDB). The wide scatter in δ180 values probably reflects physiological (non-equilibrium) effects in calcification rather than paleoenvironmental variations. Mean δ180 values for oysters, pendant bivalves, and belemnites (all calcitic) and nuculacean bivalves (aragonitic) correspond to precipitation at isotopic equilibrium with non-glacial seawater at temperatures of 15°-18°. The mean isotopic paleotemperature for ammonites (aragonitic) is slightly higher (20°) but is probably not significantly different from those for other calcareous macro-invertebrates. Preliminary oxygen isotopic results on phosphate extracted from bones, teeth, and gill rays correspond to paleotemperatures of 20°–25°.

Carbon isotopic results are limited to data from calcareous benthos and nekton. δ 13C values for individual taxa are quite variable (+2 to +5 permil for aragonitic fossils, 0 to +3 permil for calcitic fossils), suggesting physiological isotope effects. Nonetheless, mean δ 13C values are consistent with calcification in seawater having a carbon isotopic composition similar to that of modern average seawater. The presumably high flux of 13C-depleted CO2 into bottom waters from the diagenesis of sedimentary organic matter is not recorded in the carbon isotopic composition of benthic fossils.

Thermal stratification implied by the oxygen isotopic record suggests the penetration of cool, nutrient-rich waters into the Lower Oxford Clay sea. Upward advection of deep waters together with runoff from adjacent landmasses must have provided sufficient nutrients to maintain the inferred high productivity of surface waters. The influence of productivity on the carbon isotopic composition of surface waters will be tested by the analysis of calcareous phytoplankton.

Thirty-eight species of larger foraminifera belonging to Nummulites, Operculina and Assilina are recorded, identified and systematically described from 5 stratigraphic sections of the Thebes Formation in the Red Sea Coast and the Nile Valley, Egypt.

According to these species the age assigned to the Thebes Formation is Lower Eocene (Ypresian).

The Nummulites species are subdivided here into 6 groups based on their evolutionary lineage following Schaub (1981). Moreover, spiral diagrams for the different species showing the relation between the number of whorls and the corresponding radius in median sections are drawn.

The primary horizons utilized in sequence stratigraphic analysis are the sequence boundary, and the maximum flooding surface which occurs within the condensed section in areas of low sediment accumulation rates. These regionally correlative surfaces can be identified on seismic reflection profiles, on wireline logs, in stratigraphic sections, and from checklists of fossil abundance and diversity. Both surfaces are time-transgressive but nevertheless can be used as correlation horizons for partitioning depositional cycles into discrete phases of relative sea-level rise and fall. Sediments deposited during rising and falling phases of sea-level form depositional systems tracts that consist of all correlative deposits of lowstand, of transgressive or of highstand phases of relative sea level.

The sequence boundary is an unconformity formed during relative lowering of and during lowstand of sea level. The unconformity correlates into basinal areas of continuous sedimentation where the age of the unconformity is determined biostratigraphically. The unconformity surface is usually recognized because of erosional truncation of underlying strata and the onlap of overlying strata of the next sequence. The sequence boundary may be represented by a marked shift in biofacies assemblages from deeper below to shallower above. It may be marked also by an increase in reworked or displaced fossils, and by a decrease in both fossil abundance and diversity due to rapid accumulation of sediment in the shallow water, high-energy environments associated with the erosional unconformity.

The maximum flooding surface is defined by, and can be identified by, the most landward onlap of marine strata immediately below the progradational unit with downlapping onto the flooding surface. The precise age of this surface will vary along any basin margin because of the interplay of sediment supply and accommodation space. Away from the locus of major input of sediment this surface is a clay-rich condensed section formed by slow accumulation of sediment. This interval is often represented by significant increase in fossil abundance and by the deepest-water biofacies assemblage of the transgressive-regressive cycle. Despite their lateral variabilities, the seismic, lithologic and biostratigraphic signatures of the condensed section and of the associated maximum flooding surface are generally the most easily recognized and precisely dated regional correlative surfaces.

Within the axis of the depocenter, the highstand systems tract typically consists of forestepping coarsening-upward cycles deposited above the maximum flooding surface and below the sequence boundary. Fossil assemblages of the highstand systems tract reflect shallowing upward neritic conditions, with intervals in which faunal abundance decreases upwards. Transgressive systems tracts are backstepping coarsening-upward cycles deposited above the regional transgressive surface and below the maximum flooding surface. Fossil assemblages in transgressive systems tracts show deepening-upward biofacies and an increase in faunal abundance upward. Lowstand systems tracts are most significant seaward of the shelf-edge, and consist of depositional thicks with low fossil abundance. These lowstand systems tracts are separated by highly fossiliferous condensed sections containing the distal aspects of the transgressive and highstand systems tracts.

Identification of each sequence boundary and its correlative conformity, and of each maximum flooding surface is achieved by careful recognition of patterns of stratal terminations, by correlation of those stratal surfaces of discontinuity with measured sections or wireline logs, and by biostratigraphic correlation between these sections and logs. If the discontinuity surfaces correlate throughout the depositional basin or subbasin, they should be considered sequence boundaries and maximum flooding surfaces. If the surfaces are limited to local areas and are not coeval, they are probably local discontinuities associated with local structural events or with autocyclic shifting of sediment accumulation.

To date, most macroevolutionary studies have focused on taxonomic data; there are very few data sets that provide a large enough statistical population for extensive macroevolutionary studies involving direct morphometric data. The Cenozoic planktonic foraminifera are exceptional in this regard. Digitally captured shape descriptions of 342 species of Cenozoic planktonic foraminifera have been combined with the available data on their phylogenetic relationships to examine the interplay between speciation rates, size change, and various geometric characters. The results tend, at least for the planktonic foraminifera, to support Stanley's (1973) hypothesis regarding the causal mechanisms behind Cope's Rule. The tendency toward size increase may result from the disadvantages of large size during times of mass extinction rather than from the (conventionally assumed) advantages of larger size.

Additional results derived from morphotypic longevities and morphotypic turnover rates suggest an enhanced probability of speciation early in the Cenozoic, and enhanced longevity in the later Cenozoic.

Microevolutionary studies of patterns of changing variance within the Paleocene and Eocene genus Morozovella suggest that conventional foraminiferal taxonomic practice may not accurately reflect biological realities within the group, thus implying that our macroevolutionary results might be interpreted in other ways.

Paedomorphosis has now been seen in several foraminiferal lineages, including Morozovella angulata, a focus of the present study. Isotopic data (Shackleton, Corfield, and Hall, 1985) suggests that evolution of this group is accompanied by the invasion of a stratified water column. These observations suggest that one might look for systematic macroevolutionary morphologic tendencies in chamber expansion rate and size as a guide to understanding paleoecological conditions. It also seems reasonable to suggest that the complex morphological changes seen in the morozovellids may not represent morphological adaptation, but resource-related heterochronic shifts with ancillary morphological consequences.

In many cases, it is not possible to explain evolutionary-scale patterns by analogy to ecological processes. However, in at least some cases, biological interactions appear amenable to such extrapolation. The paleobiological literature contains examples of predation, competition, and herbivory in which the dynamics are similar on multiple spatiotemporal scales.

Dense populations of epifaunal, suspension-feeding ophiuroids, or brittlestar beds, are widely distributed, but they are rare and are restricted in their habitat distribution. On a small scale (meters to kilometers, hours to days), brittlestar bed distribution in the British Isles and the Bahamas is limited by predatory fishes and crabs. On an intermediate scale (tens to hundreds of kilometers, decades to centuries), predation by seastars may cause cycles of ophiuroid abundance in the western English Channel, beyond the stringent restrictions imposed by fish and crab predators. On a large scale (globally, millions to tens of millions of years), the Jurassic decline of brittlestar beds is associated with the diversification of predatory teleosts, neoselachian sharks, and decapod crustaceans.

Small-scale predator-ophiuroid interactions sum to produce analogous intermediate- and large-scale interactions. Predation effects on brittlestar beds appear to be scale-independent, or fractal. Fractal scaling may be a consequence of self-organized criticality, an inherent property of large, interactive systems.

Calcareous nannoplankton diversity varied greatly during the Paleogene. From extremely reduced values (~10 species) in the early Paleocene (circa 66.4 to 66 Ma, age estimates from Berggren, Kent and Flynn, 1985) following the terminal Cretaceous extinctions, diversity increased progressively throughout the late Paleocene and early Eocene and reached a maximum (~120 species) in the early middle Eocene (circa 52–48 Ma). This was followed by a step-like decrease until the early Oligocene (circa 35 Ma) when minimal values (~37 species) were reached once again. After a stable low during the remainder of the early Oligocene, a moderate, increase occurred near the early/late Oligocene boundary (circa 30 Ma).

Temperature has been regarded as the most important factor controlling the distribution of the calcareous nannoplankton following the characterisation of five temperature-controlled assemblages of living Coccolithophoridae in the Atlantic Ocean. Studies relative to variations in diversity in the calcareous nannoplankton throughout the Mesozoic and Cenozoic and among the extinct late Paleocene to Pliocene group Discoaster, and to changing biogeographic patterns during the Cenozoic have revealed an apparent relationship between composition of calcareous nannofossil assemblages and temperature as deduced from isotopic studies. This relationship, which is currently used to infer Paleogene climatic and oceanographic evolution from quantitative analyses of calcareous nannofossil assemblages, is however not a simple one as indicated by the fact that maximum diversity during the Paleogene (i.e., the early middle Eocene) did not occur during (but subsequently to) the warmest time (i.e., the latest Paleocene-earliest Eocene).

Diversity changes in the Paleogene calcareous nannoplankton are strikingly similar to diversity changes in the Paleogene planktonic foraminifera, which have been shown to reflect fluctuations in nutrient availibility as indicated by oxygen and carbon isotopes. The parallel evolution in the two groups thus suggests that trophic levels in the photic zone played an important role in the Paleogene diversification of the calcareous nannoplankton. In the present day ocean, the calcareous nannoplankton (Coccolithophoridae) dominate the phytoplankton under oligotrophic conditions and tropical waters are characterized by highly diversified associations with strong vertical specific stratification. Only few species occur under meso- and eutrophic conditions, and there is no vertical stratification. Extremely low diversity during the earliest Paleocene followed by increasing diversity through the Paleocene and earliest Eocene is interpreted as reflecting the change from an essentially mesotrophic to an oligotrophic ocean, increased rates of speciation resulting from niche partitioning occasioned by increased oligotrophy, leading to strong vertical stratification of species in the photic zone. Decrease in diversity from middle Eocene to early Oligocene reflects, on the other hand, progressive eutrophication of the ocean as a result of climatic deterioration.

The Paleocene to early Eocene sequence of Wyoming-Montana and the Miocene to Pleistocene Siwalik record of Pakistan are exceptionally long, continental sequences, each containing a rich and well documented fossil record, especially of mammals. The two sequences are broadly similar in tectonic setting and sedimentary environment, in duration and facies changes, and in diversity of fossils. Each contains a paleoclimatic record in stable isotopes and, in the Paleogene, floras. Comparison of these two sequences has focused our attention on the interaction of tectonic, climatic, sedimentologic, and taphonomic factors that produce a particular fossil record and on the co-occurring ecological and evolutionary changes that result in a historical series of biotas, each the product of local and global events.

In the Paleogene record, the geographic scope of the record encompasses much of the floodbasin, and the spatial distribution of paleoenvironments formed fairly straightforward gradients from channel to distal floodplain. The Siwalik record has a smaller window onto a larger, heterogeneous fluvial system often with multiple, contemporaneous river systems that differ in magnitude. The spatial distribution of paleoenvironments was a mosaic without long proximal to distal gradients. In both records, major facies changes are correlated with striking changes in fossil productivity.

The overall pattern of fossil preservation by depositional environment differs substantially in the two areas. The Siwalik sequence has a greater variety of depositional environments that produce fossils throughout the section. The primary productive environment in the older part of the Paleocene record declined in productivity upsection, while a previously unproductive facies became the major source of fossils. Much of the record represents attritional accumulation in each area, but a significant portion is transported. The taphonomic processes that created fossil concentrations led to better taxonomic resolution for most Paleogene localities than in most Siwalik localities.

In each record, both aquatic and terrestrial components of the vertebrate faunas are correlated with facies. Since facies varied in productivity over time, some changes in faunal composition may have resulted from change in the prevalence or productivity of particular facies. At least one faunal turnover coincided with major facies changes in each sequence.

For mammals in each record, immigration rather than speciation in situ was the primary means of appearance of new species. Episodes of immigration were not closely followed by extinctions of resident species. Mean species longevity appears to have been more than twice as great in the Neogene than in the Paleogene record. Changes in faunal composition and species richness occurred during times of global climatic change; causal connections are still being explored. Changes in species richness did not track changes in relative abundance of taxa or changes in size within lineages or faunas. In terms of guild structure, the herbivore guild had high relative generic diversity through most of both sequences. The Paleogene record had a more even distribution of taxa in the five principal guilds, while the Siwalik record was heavily dominated by the herbivore guild. Size distributions differed substantially, reflecting the early and late windows into the mammalian radiation, rather than sampling bias.

Regional study of Middle-Late Ordovician and Middle-Late Devonian carbonate and siliciclastic deposits in the northern Appalachian foreland basin reveals a prominent pattern of eastward-darkening of marine mudrocks and associated fossils. Exoskeletons of certain trilobite genera transform from a saddle brown coloration in southern Ontario exposures to black and near-black in central and eastern New York. Similar eastward darkening of mudstones and argillaceous carbonate units is observed to be covariant with conodont color alteration (C.A.I.) values across this same region. This pattern is coupled with other lines of evidence for eastward increases in heat-of-burial for strata across New York State, indicating that the darkening is linked to this control. Laboratory heating of thermally “cold”, light-colored samples shows that this process can be simulated under controlled conditions. The darkening of fossils and mudrocks probably occurs due to thermal maturation of organic matter within these materials.

Darkening of certain fossiliferous mudrock facies from color values as high as N 7.5 at a C.A.I. of 1.0 to those of N 2.5 at C.A.I. of 3.5 has important implications for paleoecological interpretations. Where obvious fossil-rich beds are absent and field work cursory, it might be tempting to infer a shelf-to-basin transition in the uprank direction where none exists. Where skeletal packstone and grainstone beds are common in thermally mature deposits it is possible that intervening dark-colored shales may be erroneously interpreted as basinal, organicrich (black) shales and the grain-supported beds as turbidites, when, in fact, such beds are shallow-shelf tempestites. We believe that similar value gradients should be present wherever local or regional heat-flow anomalies or differential burial patterns are developed. Foreland basins bordering orogens should contain such gradients and workers must be alert to this illusory color effect when working on complex facies in such settings. It is probable that many paleoenvironmental judgments may have been colored by misinterpretations of this type.

The thin-plate spline (TPS), a new technique for comparing shapes using landmark data, has been developed by Fred Bookstein and programmed for microcomputers by F. Rohlf. TPS generates a mapping function describing the deformation necessary to superimpose one set of landmarks exactly onto a second set of homologous landmarks, after first adusting for orientation and overall size. The mapping function is then used as an interpolant to plot a grid which geometrically represents the deformation. The TPS grid is a mathematically formalized equivalent to the Cartesian transformation grid (CTG) introduced in 1917 by D'Arcy Thompson, a technique which requires construction by eye, brain, and hand.

TPS is used here to “replicate” Edwin Colbert's 1935 CTG analysis of shape change from Subhyracodon occidentalis, a primitive fossil rhino, to Rhinoceros unicornis, a derived living form. Twenty-two landmarks were defined on Colbert's original line drawings and coordinate data was retrieved by digitization. TPS analysis of this data was nearly instantaneous using an 80386 20MHz PC.

TPS mapping of S. occidentalis onto R. unicornis produces a transformation similar to Colbert's CTG (differing most at the mandibular angle) and reveals both global and local aspects of the shape change. The global changes are dorsoventral heightening and rostrocaudal shear. Local changes include rostrocaudal shortening in the occipital and preorbital regions and rotations of the occiput and rostrum toward each other (producing the saddle-shaped skull of R. unicornis).

The functional consequences of these changes may be interrelated. For example, the upward and forward displacement of the occiput in R. unicornis suggests a change in head posture (nuchal attachment and range of motion) and a change in masticatory processing (increased vertical action of the temporalis muscle). Both functional changes may relate to dietary preference.

The first two ranks above the species level in the traditional Linnean hierarchy — the genus and family — are species based: genera have been erected to unify groups of morphologically similar, closely related species and families have been erected to group genera recognized as closely related because of the shared morphologic characteristics of their species. Diversity patterns of traditional genera and families thus appear congruent with those of species in (a) the Recent (e. g., latitudinal gradients in many groups), (b) compilations of all marine taxa for the entire Phanerozoic (including the stage level), (c) comparisons through time within individual taxa (e. g., Foraminifera, Rugosa, Conodonta), and (d) simulation studies. Genera and families often have a more robust fossil record of diversity than species, especially for poorly sampled groups (e. g., echinoids), because of the range-through record of these polytypic taxa. Simulation studies indicate that paraphyly among traditionally defined taxa is not a fatal problem for diversity studies; in fact, when degradation of the quality of the fossil record is modelled, both diversity and rates of origination and extinction are better represented by including paraphyletic taxa than by restricting data to monophyletic clades. This result underscores the utility of traditional rank-based analyses of the history of diversity.

In contrast, the three higher ranks of the Linnean hierarchy — orders, classes and phyla — are defined and recognized by key character complexes assumed to be rooted deep in the developmental program and, therefore, considered to be of special significance. These taxa are unified on the basis of body plan and function, not species morphology. Even if paraphyletic, recognition of such taxa is useful because they represent different functional complexes that reflect biological organization and major evolutionary innovations, often with different ecological capacities. Phanerozoic diversity patterns of orders, classes and phyla are not congruent with those of lower taxa; the higher groups each increased rapidly in the early Paleozoic, during the explosive diversification of body plans in the Cambrian, and then remained stable or declined slightly after the Ordovician. The diversity history of orders superficially resembles that of lower taxa, but this is a result only of ordinal turnover among the Echinodermata coupled with ordinal radiation in the Chordata; it is not a highly damped signal derived from the diversity of species, genera, or families. Despite the stability of numbers among post-Ordovician Linnean higher taxa, the diversity of lower taxa within many of these Bauplan groups fluctuated widely, and these diversity patterns signal embedded ecologic information, such as differences in flexibility in filling or utilizing ecospace.

Phylogenetic analysis is vital for understanding the origins and genealogical structure of higher taxa. Only in such fashion can convergence and its implications for ecological constraints and/or opportunities be understood. But blind insistence on the use of monophyletic classifications in all studies would obscure some of the important information contained in traditional taxonomic groupings. The developmental modifications that characterize Linnean higher taxa (and traditionally separate them from their paraphyletic ancestral taxa) provide keys to understanding the role of shifting ecology in macroevolutionary success.

The thermal physiology of extinct reptiles has been a hotly debated topic for the last two decades, with no direct evidence available to help solve the debate. Oxygen isotopes are fractionated with respect to temperature between an animal's body water and bone phosphate, thus providing avenues for deriving the first direct evidence of dinosaur thermal physiology.

Multiple samples from both cortical and cancellous areas from individual bones were sampled in order to determine the heterogeneity of δ18O values within single bones. Bones from both the body core (ribs and vertebrae) and the extremities (limbs and caudal vertebrae) of known individual dinosaurs were sampled in this method. This allows for a comparison of isotopic heterogeneity from bones of all body regions. In ectothermic heterotherms or mass homeotherms the δ18O values from the extremities are expected to generally be heavier than those from ribs or dorsal vertebrae. It is also expected that there would be a greater degree of heterogeneity of δ18O values from bones in the extremities than those in the body core for these individuals. This relationship would result from the greater degree of heat loss from the extremities than body cores due to greater surface areas and distance from the heart. This relationship has been seen in analyses on bones from the modern Varanus komodoensis. On the other hand, true endothermic homeotherms should show a very narrow range of hetergeneity of δ18O values both within individual bones and between bones within single individuals as seen in modern mammals.

Dinosaurs analyzed indicate isotopic heterogeneities within individual bones intermediate between modern mammals and Varanus, with the Tyrannosaurus showing the greatest isotopic variability. However, this isotopic heterogeneity is relatively small and is not significantly different for bones from the body core and extremities. This indicates that heterogeneity of the δ18O values is most likely the result of variations in drinking water δ18O values throughout an individual's lifetime rather than daily or seasonal variations in body temperatures.

The fluvial Neogene Siwalik formations of northern Pakistan contain one of the longest and richest sequences of terrestrial vertebrate faunas known. The complete sequence extends from ca. 18 Ma to 1 Ma, with the interval between 18 and 7 Ma being best sampled. Throughout this best known interval vertebrate remains are frequently abundant in channel fills and less common in large channel sands, levees, and paleosols. Although the abundance and quality of fossil preservation varies, all stratigraphic levels have some fossils and the record of most subintervals is good to excellent. As a consequence the patterns of faunal turnover and changes in diversity can be documented and analyzed for 0.5 my long subintervals.

Thirteen orders of Siwalik mammals have been identified, with well sampled subintervals typically having 50 or more species. Despite the ordinal diversity, however, most Siwalik mammal species belong to just three orders: rodents, artiodactyls, and perissodactyls. Among the larger mammals, the bovids and equids are the most common and have the most species, while the murid and cricetid rodents dominate the small mammal assemblages. These Siwalik abundance and diversity patterns differ markedly from those of the Paleogene and are a result of Neogene radiations in these four families and extinction of Paleogene groups.

Between 18 and 7 Ma species diversity varies considerably. Among artiodactyls and rodents the number of species first increases between 15 and 13 Ma and then falls after 12 Ma. Significant changes in relative abundance are also known, including an increase in the abundance of bovids between 16.5 and 15 Ma and a very abrupt increase of murids at 12 Ma.

Data on stratigraphic ranges of rodents and artiodactyls show that faunal change in the Siwaliks was episodic, occurring as short intervals with high turnover, followed by longer periods with considerably less change. Maxima of first appearances occur at approximately 13.5 and 8.5 Ma, while maxima of last appearances come at 12.0, 9.5, and 8.0 Ma. It is thus apparent that in the Siwaliks increased extinction did not accompany or closely follow maxima of first appearances.

Correlations of these faunal events to global climatic trends are ambiguous. However, it is apparent that the middle Miocene diversification of Siwalik faunas occurred during a period of global cooling, while the late Miocene decline in diversity preceded a second episode of cooling and increasing aridity.

The Paleogene of Wyoming and Montana and the Neogene Siwaliks of Pakistan contain deposits representing a wide variety of terrestrial environments. Although fossils are preserved in all of these environments, fossil vertebrates are abundant in only certain facies. These principal preservational environments vary within and, particularly, between formations in each region.

The Bighorn and Crazy Mountain basins of Wyoming and Montana contain abundant remains of Paleocene and Eocene vertebrates. Over 1800 localities in this region have been established in the Paleocene Fort Union and Paleocene to Eocene Willwood formations. The distribution of vertebrate remains changes dramatically upsection in this sequence. The Fort Union consists of thick fluvial sandstones and minor swampy floodplain mudstones in the lower part, and more widely separated channel sandstones interbedded with better drained floodplain deposits that include paleosol horizons in the upper part. These changes reflect a local increase in aggradation rate. Vertebrates are preserved almost exclusively in channel mud-clast conglomerates in the lower part of the formation, but appear in a wider variety of environments (channels, splays, swamps, and paleosols) in the upper part. The Willwood Formation continues the changes evident in the upper Fort Union. With increased aggradation rates, floodplain deposits became thicker and more well drained. Except for rare occurrences in other environments (channels, a variety of calcareous environments, and oxbows), fossils are recovered primarily from paleosol horizons developed in fine grained floodplain deposits.

The Fort Union channel deposits contain assemblages that are often highly biased samples of faunal composition with large aquatic taxa well represented and small terrestrial forms unevenly represented. The upper Fort Union and Willwood floodplain paleosols contain more homogeneous (and therefore comparable) assemblages. These paleosols differ systematically, however, in terms of soil maturity and vertebrate composition, and they are commonly biased against large or aquatic taxa.

The distribution of Siwalik vertebrate localities among sedimentary environments is known for four formations spanning early middle to late Miocene: Kamlial, Chinji, Nagri, and Dhok Pathan. The principal deposits in which fossils occur are: major stream channel complexes, secondary (floodplain) channels, crevasse splays, and floodplains. The Kamlial and Nagri formations, dominated by coarse lithologies (>50% sandstone), are notably less productive of fossil localities than the Chinji and Dhok Pathan formations, dominated by fine grained lithologies (>50% mudstone). In the Kamlial and Nagri formations, major channel complexes form the most prevalent environment, and more localities are associated with these channels than with any other environment. In the Chinji and Dhok Pathan formations, the most prevalent environment is floodplain, but more localities are associated with the secondary channels on these floodplains than with any other environment. In the Chinji Formation, most localities developed in secondary channels occur in fining-upward fill sequences, whereas in the Dhok Pathan Formation, most sites in these channels occur in their lag deposits. In these more productive formations, the abundance of certain mammalian taxa is correlated with specific depositional environments. Change upsection in the abundance of these taxa could result largely from change in facies productivity.

The taphonomy of the two areas is similar in that channel lag deposits are an important source of fossil vertebrates. The major difference is that the Rocky Mountain Paleogene contains fewer, but highly productive, environments that changed significantly through time, including the Eocene emergence of floodplain paleosols as the primary environment of vertebrate preservation.

Do organismal characteristics influence evolutionary histories of taxa? This important question has been answered in the affirmative for a variety of organisms, and here it is applied to the echinoderm class Crinoidea. The approach used in answering this question involves (1) identifying a relevant trait through functional analysis, (2) demonstrating its ecological significance, and (3) testing the hypothesis that the ecological characteristics affect evolutionary rates.

Crinoids, like all passive suspension feeders, depend on externally driven flows to supply them with necessary particulate nutrients. Particles are captured with feeding appendages which function as filters. Filters act as obstacles to the flow and their morphology influences how much fluid can be filtered at a given current velocity: fine filters, because of their higher resistance to flow, sample less fluid and fewer potential food items than coarse filters. This suggests that filter morphology may be important in controlling the distributions of crinoids among different environments: at low current velocities fine-filtered crinoids may not capture sufficient particulate nutrients to satisfy their energy needs.

To quantify the effect of filter morphology on particulate nutrient capture, an energy budget equation was solved for two crinoid morphologies representing the fine (pinnulate) and coarse (non-pinnulate) filters. In this equation, energy inputs in the form of captured and metabolized nutrients had to exceed energy expenditures, expressed as the standard metabolic rate. The solution of the equation showed that the current velocity below which crinoids are at an energy deficit is higher for the fine-filtered (pinnulate) than the coarse-filtered (non-pinnulate) taxa.

The higher minimum velocity of fine-filtered crinoids restricts them to environments with higher current velocities; coarse-filtered taxa are less constrained and may occupy a broader range of environments. This pattern is borne out by the distribution of Mississippian crinoids studied by Kammer and Ausich (1987). With regard to current velocities, the fine-filtered crinoids may be described as “specialists” and the coarse-filtered crinoids as “generalists”. The specialist/generalist strategies of the two groups suggest an evolutionary scenario in which the fine-filtered crinoids are more prone to speciation and extinction.

To test the above scenario the evolutionary rates of two morphological groups, fine-filtered crinoids (camerates) and coarse-filtered crinoids (non-pinnulate Paleozoic crinoids), were compared. As predicted, the former group had higher extinction and origination rates. A “bootstrapping” technique revealed that the differences in extinction rates were statistically significant (P < 0.05).

The filter morphology-evolutionary rate scenario, however, fails to predict the durations of two other fine-filtered (pinnulate) crinoid groups: the Paleozoic cladids and their descendants, the post-Paleozoic articulates. Though fine-filtered, these taxa had broad environmental distributions and the lowest extinction rates among the Crinoidea. They are also the only crinoids with muscular arm articulations. This “evolutionary innovation”, by allowing a greater degree of morphological and behavioral flexibility, allowed these crinoids to occupy a broader range of environments and may in part explain their “anomalous” evolutionary rates.