The Siwalik sequence, particularly the interval from 18 to 7 Ma, provides one of the few terrestrial data sets that allows direct measurement of temporal durations of mammalian species. Its data are drawn from a single biogeographic subprovince and superposed collections likely represent successive samples of single lineages. Observed temporal ranges underestimate total species longevities if (1) species existed in other biogeographic provinces before or after the temporal ranges recorded in the Siwaliks, or (2) the fossil record inadequately samples species durations in the Siwalik subprovince. Some data, notably from Afghanistan, China, and Thailand, bear on the first variable. The second can be controlled by considering data quality, in this case the temporal distribution of good data sets, to assess the scale of accuracy available for defining range endpoints. In general, range endpoints can be estimated to the nearest 0.1 million years.

The diverse Rodentia give a mean species longevity of 2.2 million years for the Miocene Siwaliks. This includes single records, but of course ignores unretrieved rare or short-lived taxa. The diverse Artiodactyla yield 3.1 million years. The difference may reflect greater body size and longer generation time; large Perissodactyla and Proboscidea have longer temporal ranges. Carnivorous mammals also show about 3 million year durations. Given these data, the average longevity for Sivapithecus species (1.6 million years) is modest. The deposits of the Clarks Fork Basin, Wyoming, offer a Paleogene data set comparable to that of the Neogene Siwaliks. Paleocene-Eocene mammals of North America yield shorter longevities (most less than one million years).

Extinction is the dominant mode of species termination for Siwalik mammals. Most taxa originated by immigration (as at about 13.5 Ma) or abrupt speciation. There are some cases for insitu transformation of lineages, for example in the genera Punjabemys, Antemus, Percrocuta, Dorcatherium, Giraffokeryx, and Selenoportax. The rodent Kanisamys shows a rate of increase in tooth size of 0.5 darwins. This overall rate is moderate by Paleogene standards, but includes an interval of more rapid change between 9.0 and 8.5 Ma.

Morphological diversity (MD) is important for understanding a clade's evolution and for comparing clades to discover evolutionary laws. As the scale of analysis (taxonomic rank) increases, defining a morphological space becomes less tractable, and assessing MD becomes more difficult. Continuous morphometric variables are hard to define for very disparate species, but morphological dissimilarity can be assessed by discrete characters. I use this approach to document the history of MD in the echinoderm subphlylum Blastozoa.

About 60 discrete characters were defined, relating to: arrangement and number of thecal plates; shape and symmetry of theca; number, arrangement, form, and plating of ambulacra; arrangement, form, and plating of brachioles; form and plating of attachment structure; nature of respiratory structures; and position of mouth and anus. Character difference for binary and unordered multistate characters is 0 for matches and 1 for mismatches. Ordered multistate characters were scaled so that the maximum character difference was unity. Pairwise dissimilarity between species was measured by the mean character difference. MD in a stratigraphic interval was measured by the mean pairwise dissimilarity among species. Over half of all described genera were represented. MD involves not only the origin of new character states but also the maintenance of primitive states in a clade; therefore, assessment of MD was deliberately not restricted to analysis of novelties! The figures below compare MD to generic diversity based on the Treatise and post-Treatise monographs.

Debate persists about the nature and extent of early echinoderm diversification. Most pertinent to this debate, MD in the Cambrian and Lower Ordovician is extremely high compared to taxonomic diversity; there are few taxa sparsely occupying much morphospace. Analysis of clade-shape statistics indicates that the blastozoan clade is bottom-heavy in both aspects of diversity, but more so with respect to MD. The results overall are not sensitive to the details of the time scale, the inclusion of problematic forms, or the number of characters used. The general picture agrees with that advocated by Sprinkle (among others) for the echinoderms as a whole.

The compound eyes of trilobites provide the best examples of fossilized sensory organs for which the function in life can be worked out today, because the optical array of their corneal lenses preserves the geometry with which the eye originally sampled the visual world. An analysis of trilobite vision is strengthened by the use of new mathematical approaches to compound eye design. In particular, the product of the facet diameter (D) and the interommatidial angle (Δϕ) gives the value of the eye parameter, DΔϕ, which is a reliable indicator of the photic conditions in which the eye was used. In modern arthropods, DΔϕ values range from 0.3 for animals active in bright sunlight to 20 or more for nocturnal or deep-sea animals.

Three types of compound eyes existed in trilobites: schizochroal, holochroal, and abathochroal. We examined the schizochroal and holochroal types. Schizochroal eyes were studied in the phacopid species Phacops rana crassituberculata and Phacops rana milleri. We measured the diameter of every corneal lens, and estimated its optical axis by taking the normal to the plane of the lens's diameter. In both species, each eye covered almost exactly 180° of visual space in azimuth with no binocular overlap, from directly anterior to directly posterior. Vertically, the visual field extended from the horizon to about 40° in elevation. Facet diameters and interommatidial angles were large, giving eye parameter values ranging from 10 to > 150. These are much greater than in any living arthropod, implying that modern compound eye theory does not apply to schizochroal eyes. We believe that each ommatidium of the schizochroal eye served as a miniature lens eye. If so, phacopid vision must have been unique, with multiply overlapping visual fields. Such a design would have required considerable central processing, but could have provided exceptional opportunities for spatial, spectral, and polarizational analysis.

We examined holochroal compound eyes in Asaphus cornutus and Isotelus “gigas”. Here, visual field coverage was greater than in the schizochroal eye type, with a small amount of frontal binocular overlap. Holochroal eyes contain far more ommatidia than do schizochroal types, reducing both facet diameter (D) and interommatidial angle (Δϕ). Thus, DΔϕ values in these species fall into the same range as in modern compound eyes. This implies that function of the holochroal eye was similar to that of modern crustaceans and insects.

This material is based on research supported by the National Science Foundation under Grants No. BNS-8518769 and BNS-8917183.

Because trilobites occupied a wide a range of Paleozoic marine habitats they are a good group to examine hypotheses concerning the sites in which new major clades first appear, and their subsequent history of diversification and decline. There are several problems in this endeavour. The first concerns classification. Until a complete phylogenetic classification is available, there is no objective way to assess the equivalence or otherwise of groups which have been claimed as orders. For example, Odontopleurida and Lichida are treated as separate orders in some classifications, but are considered as a single major clade - presumably of ordinal status - in others. Some of the most commonly accepted groups (Olenellida, Ptychopariida) are paraphyletic. The second problem is taphonomic. The first appearance of a major group often coincides with a major extrinsic change, such as a regressive-transgressive couplet. Does the event initiate the novelty, or simply permit it to be preserved? Does such an event “punctuate” the fossil record, such that earlier, ancestral taxa belonging to the same clade go unrecognised?

Trilobites are already paleogeographically diversified when they make their first appearance in the Lower Cambrian. Since trilobites constitute a true clade, this implies an earlier phase of vicariance of dispersal which is not recorded in the rocks. In China, Siberia, North America, and North Africa these first occurrences are in rocks of inshore origin: still earlier trilobites may have had thin cuticles which militated against their being preserved in the highest energy environments where “small shelly” fossils occurred. The groups Olenellida, Redlichiida, Corynexochida, Ptychopariina (?Lichida) appear in the early Cambrian. The earliest polymerids with morphology corresponding to deep water, atheloptic, is latest Lower Cambrian (Atops, Australia): there are many such in the mid-Cambrian.

Opinions differ on the classification of Agnostida. Our own view relates Agnostina to Eodiscina, and on this view the early representatives of the clade (Lower Cambrian, China) are inshore compared with later agnostid occurrences, which typify outer shelf to slope. Ordovician agnostids are comparatively rare; the youngest agnostids were not confined to deep water sites.

There is good evidence of early occurrences of Odontopleurida, Lichida s.s., Illaenina, Proetida and Phacopida in shallow water deposits. Evidence from Asaphida is more equivocal. Colonisation of deeper water habitats from shallow is rapid, although not achieved at the same time in each group. The scenario is of repeated production of deeper water forms from shelf taxa rather than wholesale movement of clades into that environment. After the demise of other groups in the late Devonian, for example, in the youngest Devonian and Carboniferous proetides radiated into deep water habitats. But the last trilobites of all in the Permian were shallow shelf inhabitants.

Studies of Eocene angiosperm pollen floras in eastern North America (my work, especially in the eastern Gulf Coast) and western Europe (Boulter, Krutzsch) have shown significant differences in floral diversities between the two regions: in western Europe, maximum diversity was in the early Eocene and it decreased thereafter, in eastern North America, maximum diversity was in the middle part of the middle Eocene. The hypothesis presented here is that paleogeography was an important control on the diversity histories in the two regions: eastern North America was part of a large terrestrial landmass, whereas the terrestrial depositional basins of western Europe were on islands or peninsulas surrounded by the sea. Migrations between eastern and western North America were relatively easy, but migrations within what is now western Europe involved island-hopping, which explains distinct diachroneity of some angiosperm first appearances among different basins there. Western European basins were in contact with a large land mass during late Paleocene time but became isolated and smaller during the middle to late Eocene marine transgression. These changes resulted in decreased genetic exchange and increased probabilities of extinction due to (1) greater competition among species because of a reduced number of niches and (2) presence of small, isolated species populations, leading to local variations in extinctions, which probably explain the observed diachronism of taxon last appearances in different areas of Europe. Terrestrial climatic cooling in western Europe may be linked to decreasing contact between the NW European Tertiary Basin and the warm Tethys Seaway during the middle and late Eocene. In short, some combination of low environmental heterogeneity, geographic isolation, and long-term climatic deterioration probably caused the decrease in angiosperm diversity during the middle and late Eocene in western Europe.

Several factors encouraged increasing or stable diversity in eastern North America but were far less effective in western Europe: (1) Eastern North America underwent greater climatic fluctuations during the Eocene (thus, immigration of taxa with different climatic preferences took place at different times), whereas the islands and peninsulas of western Europe had more uniform, maritime climates. (2) Evolution and immigration of r-selected taxa in eastern North America were favored by distinct dry seasons at certain times during the Eocene and by repeated marine transgressions and regressions that created opportunities for evolution and immigration of r-selected plants on and to freshly exposed coastal plain. In contrast, the predominantly maritime climates of western Europe in the early and middle Eocene favored K-selected plants, which had fewer possibilities for evolution and which had greater difficulty in migrating because island-hopping taxa are mainly r-selected. (3) “Arcto-Tertiary” taxa adapted to cooler climates lived and evolved in the uplands of the Appalachian Mountains, whereas western Europe was relatively flat in the Eocene –another example of its relative lack of environmental heterogeneity.

General environmental correlation, established for trace fossils, is hard to apply to modern sediment cores, for which environmental factors can be measured directly - at least with regard to the top layers. Reasons for this difficulty are obvious: (1) Outcrop volume is limited by the core diameter. (2) Biogenic structures are hard to see, because they have not yet been “developed” by diagenetic processes. (3) Cores are traditionally studied in vertical cuts, in which search patterns parallel to bedding plane - typical for deep-sea environment - are poorly expressed. Therefore cores from the North Atlantic were studied not only by traditional X-ray radiography (both vertical and horizontal cuts), but by computer tomography (CT), which renders series of sections parallel to the bedding plane, as well as a three-dimensional picture, without destroying the valuable core.

On the Iceland-Faeroe Ridge, the distribution of ichnocoenoses appears to be largely controlled by microenvironments in connection with local channel systems and their lateral migration. In a local, ridge-parallel channel system at the southern slope, a core from the NE flank shows a vertical alternation of Zoophycos, Trichichnus, and Planolites communities correlating with fluctuations of CaCO3 and the fraction >63μm. In contrast to this, on the opposite slope, sediments are uniform and dominated by Scolicia. On the colder N slope of the ridge, topography is more uniform and the water motion is sluggish. The characteristic and dominant ichnogenus is Chondrites. On top of the ridge the sediment cover becomes very thin, contains large amounts of dropstones, but still Chondrites is dominant.

The mammalian order Xenarthra (including the living Neotropical armadillos, anteaters, and tree sloths) has figured importantly in recent hypotheses of interordinal relationships among eutherian mammals. It has been suggested that the group shares a common ancestry both with the extant Old World order Pholidota (i.e. the pangolins or scaly-anteaters) and the extinct North American group Palaeanodonta. Furthermore, these three groups have been linked together into a monophyletic Cohort Edentata, which has been hypothesized to represent the sister-group to all other eutherians. This placement of edentates relative to the remainder of Eutheria has been supported in part by a purported difference in the morphology of the stapes in the two groups- edentates possessing a primitive, imperforate/columelliform morphology, other placentals a derived, perforate/stirrup-shaped morphology.

A recent study of stapedial morphology among mammals by Novacek and Wyss (1986) suggests that within the Xenarthra itself a perforate stapes is found among armadillos, but that the pilosa in particular (the clade including anteaters and sloths) and the order as a whole are characterized primitively by an imperforate stapes. Our studies of the xenarthran ear region (Patterson et al., in press) have uncovered new ontogenetic and paleontological evidence which contradict the findings of Novacek and Wyss. Among adults of the two extant tree sloth genera, the stapes lacks a stapedial foramen. However, in both genera, this adult imperforate morphology is derived from a perforated juvenile stapes. Novacek and Wyss ignored fossil species in their consideration of the xenarthran stapes. It has long been known that extinct ground sloths of the family Mylodontidae possessed a large stapedial foramen. Unfortunately, until now no stapes were known from the remaining ground sloth families, the Megatheriidae and the Megalonychidae. We have uncovered a complete left stapes of an early Miocene megatheriid ground sloth Eucholoeops ingens. This stapes possesses a well-developed stapedial foramen. We believe that this new paleontological evidence, combined with our information on the ontogeny of the stapes in the living genera, clearly indicates that a perforate stapes is primitive for sloths. Moreover, when we plot distributions of stapedial morphologies of both living and fossil edentates onto a phylogeny of the Edentata, we can demonstrate that the a large stapedial foramen is primitive for the Xenarthra as a whole, and probably for the entire Cohort Edentata. Such a distribution makes it unlikely that stapedial morphology can be used to separate edentates from other eutherian mammals.

The Pliocene uplift of the Panamanian isthmus isolated previously contiguous Caribbean and eastern Pacific marine faunas, and initiated the development of different selective regimes on opposing sides of the barrier. Contrasting environmental conditions provided the context for different rates and kinds of evolutionary change on either side of the isthmus. The goal of our study is to characterize the rates and types of these paleoenvironmental changes; we employ stable isotopic profiles of venerid bivalve shells from the Miocene-Recent deposits of Panama and Costa Rica.

We analyzed geographic and depth variation in Recent shells as a means of calibrating the fossil analyses. Results from Recent venerids highlight the differences between the Caribbean and eastern Pacific shallow marine environments. Pacific shells typically exhibit strong annual fluctuations in δ18O, associated with seasonal upwelling and its associated cool waters. In shallow, near-shore habitats, freshwater runoff during the rainy season also contributes significantly to annual δ18O cycles. Caribbean shells exhibit negligible annual cyclicity.

We analyzed fossil shells from the Miocene Gatun Formation, and the Pliocene Cayo Agua, Escudo de Veraguas, and Rio Banano Formations from the Caribbean coast, and the Plio-Pleistocene Charco Azul Group from the Pacific coast. Results from fossil shells indicate that annual cycles are well-preserved, and not obscured by diagenesis or other alteration. A strong annual signal in δ18O (amplitude >1.5‰) is found back at least to the Early Pleistocene along the Pacific coast. Some post-uplift Caribbean samples exhibit stronger seasonality than that observed in similar habitats today.

The Clarks Fork Basin in northwestern Wyoming contains a thick stratigraphic section of Paleocene and Eocene fluvial sediments, parts of which are exceptionally complete and very important for quantitative study of mammalian evolution. The 1520-2270 m interval of the early Eocene in the Clarks Fork Basin, representing about 2 m.y. of evolutionary time, has been sampled on a scale of 10 m ≈ 27,000 years.

Rates of morphological change can be calculated from measurements of tooth size for successive large samples in this section. These are quantified in terms of proportional change in standard deviation units, with time in generations. Fig. 1 (lower left) shows the distribution of 548 nonzero rates for the dawn horse Hyracotherium grangeri lineage plotted on log-log axes. The distribution has a robust maximum likelihood slope of -0.923 with a bootstrapped confidence interval ranging from -0.798 to -1.041: the observed interval includes -1.00 expected for a stabilizing process (stasis), but excludes -0.50 expected for random change and 0.00 expected for a process like directional selection. Extrapolation indicates H. grangeri changed at an intrinsic rate of 0.23 standard deviations per generation on a time scale of one generation (95% CI ranges from 0.06 to 0.87). This and other examples known to date suggest intrinsic rates for lineages in stasis are indistinguishable from (no lower than) intrinsic rates for artificially selected directional change in laboratory selection experiments. Consequently, significant differences in net change observed over time cannot be explained intrinsically but must be due to extrinsic factors.

Species durations can be estimated to the nearest 0.1 m.y. for 46 well sampled lineages (open histogram in Fig. 2, lower right, cross-hatched where overlapping black Poisson distribution with same half-life λ). Median duration is 0.5 m.y., modal duration is 0.3 m.y. Note excess of both short- and long-duration species, indicating durations are neither independent of each other nor an intrinsic property of species. Here again, change and speciation, fast or slow, are probably driven by environmental factors extrinsic to the species themselves.

The Middle to Upper Ordovician graptolite taxon Orthograptus quadrimucronatus currently comprises 11 sub-species and has several closely related species. Many of these subspecies are poorly defined, having been established on the basis of stratigraphic and geographic occurrence and not morphological differences. A detailed morphometric analysis of this group indicates that all 11 subspecies of O. quadrimucronatus and the morphologically similar British species, O. pageanus, can be placed within three distinct lineages. Members of the O. pageanus lineage are characterized by long apertural spines on the first two thecae, a broad proximal end, and a wide less densely thecate rhabdosome. Specimens belonging to the O. quadrimucronatus spinigerus lineage have narrow proximal ends, rapidly widening rhabdosomes, and elongated apertural spines on the 8th to 12th thecal pairs. The O. quadrimucronatus quadrimucronatus lineage is composed of specimens with no unusual spines and rather parallel sided rhabdosomes.

Orthograptus pageanus first appears in the lower Corynoides americanus Zone and is probably derived from the O. calcaratus species group. O. pageanus retains the large basal spines, robust rhabdosomes, and long thick nema found in O. calcaratus. The thecae of O. pageanus are, however, highly derived with respect to O. calcaratus whose thecae retain the form of their hustedograptid ancestry. O. pageanus has everted thecal apertures and paired apertural spines as opposed to the introverted thecal apertures and apertural horns present in O. calcaratus. O. quadrimucronatus quadrimucronatus appears at approximately the same time as O. pageanus while O. q. spinigerus appears slightly later in Australia and Great Britain and several graptolite zones later in eastern North America. The first appearance of all three lineages in the classic graptolite-bearing rocks (Utica Shale) of the northern Appalachian basin represents immigration and not speciation. Members of the O. pageanus lineage grow rapidly in size through the C. americanus Zone and become extinct at or just above the top of the zone. The O. q. quadrimucronatus lineage shows no single trend through time, getting larger and smaller, seemingly in response to changing water chemistry and temperature. Poor preservation of collections of O. q. spinigerus make within lineage changes over time impossible to evaluate.

Specimens of these three lineages were examined across an interval of time representing four graptolite zones (C. americanus to G. pygmaeus zones) in the Middle and Upper Ordovician rocks of Australia, Great Britain and eastern North America. This interval is generally regarded as having a duration of approximately four million years. Across this interval each of these lineages appears to be a stable entity in space and time. Although there are changes in size among members of a lineage during its existence, there are no basic changes in form. Thus, the anagenetic change in these organisms does not appear to produce any new species or even sub-species. New taxa appear with no evidence of ancestral intermediates, and remain basically the same throughout their duration. This pattern is consistent with punctuated equilibrium, although anagenetic size change is also observed.

During the past two decades, biologists have become increasingly aware of the diversity and abundance of foraminifera in marine benthic ecosystems. These protists are probably the most important eukaryotes present in ocean floor communities. In some areas, particularly central oceanic regions, foraminiferal assemblages are dominated by newly discovered, soft-bodied forms with morphologies quite unlike those of “conventional” foraminifers and with little fossilisation potential. However, despite the presumed loss of these delicate forms from the fossil record, foraminiferal tests are still the only microfossils to occur commonly in ancient deep-sea sediments. Thus, they are a focus of attention for both geologists and biologists. This presentation will concentrate on two main areas of biological research which have palaeontological significance.

Foraminiferal microhabitats. Recent research indicates that particular species tend to live infaunally (deep or shallow), epifaunally or suprabenthically. Growth above or below the sediment-water interface has major implications for the stable isotope chemistry of calcareous tests, an important tool in palaeooceanography. Other species inhabit organic detritus composed of phytoplankton material rapidly sedimented from the euphotic zone. This “phytodetritus” arrives suddenly on the ocean floor following the spring bloom and is quickly colonized by foraminiferal species which feed on it, reproduce and rapidly develop large populations. These populations collapse when the food source is exhausted. The direct consumption of phytodetritus (and other organic matter inputs) by benthic foraminifers may be a widespread phenomenon which influences their population dynamics, regional distribution patterns and isotope chemistry.

Recolonization. The defaunation of large tracts of ocean floor by turbidity currents or anoxic events must have happened on countless occasions over geological time, particularly along ocean margins and in basinal areas. Evidence from sediment tray experiments suggests that it may take several years for a stable community (including foraminifers) to become reestablished in small areas of defaunated sediment. Large devastated areas may require substantially longer to recover. However, on the Madeira Abyssal Plain, a normal foraminiferal assemblage occurs on the surface of a turbidite deposited several hundred years ago, suggesting that large-scale recolonization may occupy decades rather than centuries. The fossil foraminiferal assemblages present in deep-water flysch sequences are presumably the product of similar recolonization (?successional) events.

These and other biological processes often operate on time scales (days, months, years) which usually can not be resolved in the stratigraphic record. This inevitably complicates the application of biological research to palaeontology.

The late Quaternary was a time of rapid environmental fluctuations. The last glacial maximum was reached about 20 ka with continental glaciers covering most of Canada as well as the northeastern and upper midwestern United States (U.S.). Glacial ice physically displaced entire terrestrial biomes and the cooler climates altered distributions of species outside of the glacial limits. About 14 ka, the climate began to warm rapidly and glacial ice retreated northward, opening new landscapes for colonization by terrestrial biotas. Maximum warmth was reached between 9–5 ka with a time transgressive progression from west to east.

Radiocarbon chronologies allow for fine scale (100's to 1000's of years) resolution of mammal responses to these changes. Mammal communities did not respond as intact units but individual species shifted diachronically along environmental gradients. As a result, many late Pleistocene mammal communities contain associations of extant species that do not occur together today and appear to be ecologically incompatible. Pleistocene mammal communities also had a greater diversity of species than either Holocene or modern ones. This greater diversity was, in part, due to the existence of a diverse megafauna that became extinct at the end of the Pleistocene (10 ka). However, Pleistocene small mammal guilds with extant species, especially insectivores and microtine rodents, were also more diverse. Rapid changes in small mammal species distributions, diversity patterns, and clinal shifts around 10 ka strengthens environmental models for the end-Pleistocene extinction.

Modern mammal communities began to appear at the end of the Pleistocene and into the Holocene. In the eastern U.S., the species composition of these communities has been stable for the last 10 ka, although vegetational communities have shown change throughout the Holocene. In other parts of the U.S., middle Holocene warming caused some species to shift their geographic ranges. However, species composition of communities was not significantly altered. Understanding these changes not only provides a better perspective for viewing mammal communities of the past but it may also give insight into those of the future as climate will continue to vacillate, whether induced naturally or anthropogenically.

Modern plant communities define global Biomes by their structure, floristics and physiognomy. The modern distribution and character of plant communities is determined by climate, large-scale biotic interactions and abiotic factors such as fire and other disturbance history. Biogeographic patterns also reflect past continental movements, dispersal, extinction and speciation events. The past distribution and history of the principal modern plant communities can be traced using key taxa and associations of taxa, and the foliar physiognomy of the biomal communities.

The antecedents of many modern types of vegetation can be found in the mixed plant communities of the Cretaceous and earlier. Late Cretaceous angiosperm radiation and K/T extinctions substantially altered these plant communities, setting preconditions for subsequent evolution and the floristic character of terrestrial plant communities. Paleocene vegetation appears intermediate, and the main phase of floristic modernisation appears to have been during the Eocene.

Tropical rainforests and deciduous forests of a modern aspect are well represented in Eocene macrofloras at middle and higher palaeolatitudes respectively, in North America, Europe and Australia. These forests partly reflected present day phytogeographic provincialism but many taxa exhibited past cosmopolitanism, having much reduced modern ranges. The presence of “tropical” forests at middle latitudes, well outside their present day latitudinal extent, reflects the Early to Middle Eocene thermal maximum with widespread equable, humid and subhumid climates. At higher latitudes macrofloras reflect deciduous angiosperm vegetation of lower diversity than the middle latitude rainforests. Deciduousness in these forests was probably an adaptation to seasonal darkness beyond the palaeo-Arctic circle, but at intermediate latitudes may have reflected adaptation to greater temperature seasonality. Coniferous forests are represented in Eocene macrofloras from high latitudes and from uplands in the middle latitudes. Grasses are present in some Eocene macrofloras, but grasslands do not appear in the fossil record until the Oligocene or later. They seem to be a response to climatic deterioration and an evolving mammalian biota. Forested and herbaceous wetland communities may have been more diverse and latitudinally more uniform in the Palaeogene than today, but are otherwise quite modern. Post Oligocene history of most plant communities is that of climate altered distribution and floristic extinction.

Echinoderms were among the earliest phyla to exploit global environmental shifts leading to the rise of the Paleozoic Evolutionary Fauna during the Ordovician. Echinoderms including crinoids and rhombiferans diversified more rapidly and actually precede other groups such as bryozoans, corals, and many articulate brachiopods in the record. We argue that preadaptive morphologic strategies among the echinoderms coupled with newly available and widespread living space led to this success.

Sessile attached echinoderms, especially crinoids and some blastozoans, dominate echinoderm faunas generally throughout the Paleozoic. These organisms were rheophilic suspension feeders with elongate stalked morphologies capable of attaining high feeding levels above competitors. However, this morphology required firm attachment. Suitable sites were relatively rare in Early and especially Middle Cambrian time when shelf and slope sedimentation was dominated by fine siliciclastics and nonbiogenic carbonates resulting in extensive soft substrates. Sea level was relatively low during the Middle Cambrian, restricting shallow shelf living space. Stalked echinoderms then lived attached to scattered bioclastic fragments but had low diversity and were a relatively minor component of the faunal record. Mode of occurrence and morphologic features suggest they were generally unable to cope with soft and unstable substrates. Nearshore shelf sedimentation styles changed during the Late Cambrian and Early Ordovician to bioclastic-dominated carbonates and organic buildups. These were often subject to intermittent storm events and rapid submarine cementation of the seafloor because of changes in global atmospheric and seawater chemistry. This resulted in formation of hardgrounds on intraformational conglomerates, grainstones, and buildups. Gradual sea level rise beginning in the Late Cambrian and continuing through the Early Ordovician was a major contributing cause for these changes. The widespread lithified substrates provided ideal attachment sites for the preadapted echinoderms and greatly expanded the total habitable area, resulting in rapidly increasing diversity.

Among crinoids, disparid inadunates were the first to extensively exploit this situation and they dominated throughout the Early Ordovician. Attached blastozoans were also common both in the Late Cambrian and Early Ordovician. Later, many camerate and cladid inadunate crinoids and a few blastozoans developed attachment styles suitable to soft substrates, continuing and expanding this diversification. Some previous authors have misidentified life modes of these Cambro-Ordovician echinoderms because they used forced senarios based on phylogenetic analysis alone. In contrast, we argue that life modes and paleoecologic settings are basic field-derived data that should be used along with morphologic character analysis to determine phylogenetic relationships. Both the fossils and their environmental settings must be studied together to reconstruct the adaptive history and phylogeny of a rapidly-radiating group.

We examined guild structure and diversity in the mammalian biota of the Paleogene of Wyoming and Montana and the Neogene of Pakistan. Trophic structure was measured as frequency of generic diversity in each of the following trophic categories: insectivore, omnivore, frugivore, herbivore, and carnivore. Trophic categories were inferred from dental morphology.

Results are summarized below (see graphs). In Wyoming/Montana, the Paleocene is dominated by herbivores (from the orders Condylarthra, Multituberculata, and Pantodonta) and insectivores (“Proteutheria” and Proprimates). In the early Eocene, herbivores (Perissodactyla, Artiodactyla, and Rodentia), carnivores (Carnivora, Creodonta, and Mesonychia), and insectivores (“Proteutheria,” Proprimates, and Primates) dominate. At the beginning of the Eocene, carnivores and insectivores are more diverse than herbivores, but later, herbivores are more diverse. Adapid primates become an important frugivore element in the early Eocene. Herbivores are the most common group throughout the sequence, ranging from 30% to 75% of all specimens.

In the Siwaliks, herbivores (from Proboscidea, Rodentia, Perissodactyla, and Artiodactyla) dominate in generic diversity (70–80%), with artiodactyls consistently representing about 50% of herbivore genera. Circa 16 Ma, rodents appear and become an important herbivore group. At 14 Ma, bovid diversity increases dramatically. Specialized browsers (tragulids, giraffids) and grazers (suids) represent 25% to 35% of herbivore diversity throughout the sequence. Carnivores, represented by creodonts and true carnivores, range from 5% to 20% of generic diversity in the Siwaliks. At 11 Ma, carnivores increase in generic diversity with amphicyonid and hyaenid carnivores dominating the guild. Carnivores and insectivores are never as diverse in the Siwaliks as they are in the early Eocene of North America.

Both lithologic and paleobotanic data have been used to construct climatic curves for the Pennsylvanian of the Appalachian Basin (Figure 1). The strengths and weaknesses of each type of evidence must be considered when reconciling these data into a composite curve. (1) The calibrated lithologic curve is based ultimately on the geographic ranges of sediments and soils relative to modern precipitation. Although it provides quantitative estimates of precipitation, the calibrated curve cannot detect minor fluctuations in climate, and time-averaging of range data can lead to an over-estimate of the rate of climatic change. (2) The geochemical model, although uncalibrated, uses essentially the same data as the calibrated curve. It avoids some of the problems of time-averaging by incorporating rough estimates of abundance. Although the long-term curve portrays a uniform climate during the earlier Pennsylvanian, lithologic data may be insensitive to climatic fluctuations in extremely wet climates. (3) The abundance of arborescent lycopods in coal may be a useful climatic indicator through much of the Pennsylvanian, but its usefulness in the Mississippian (before the evolution of non-lycopod swamp trees) and the latest Pennsylvanian (after a major extinction of arborescent lycopods) must be questioned. (4) The abundance of coal resources (as with any other climatic indicator) depends on many factors other than climate. The lack of congruence between the coal abundance curve and the other curves emphasizes the importance of including non-climatic factors in any model that predicts coal resources based on paleoclimate.

The composite curve takes its overall shape from the geochemical model, quantifies it using the calibrated curve, and details climatic trends in the wet lower Pennsylvanian based on lycopod abundance data. The major weakness of the composite curve is that it ignores potential variations in seasonality of precipitation.

The escalation of predator-prey interactions over the Phanerozoic is described as an “arms race” among the Gastropoda. Examples of escalation have been extensively documented on the scale of hundreds of millions of years, however, these patterns are not well documented on shorter time scales. Effective escalation of prey defenses should cause a drop in predatory efficiency. We study the efficiency of Naticid and Muricid predation upon Turritelline gastropods from the Miocene to the Pliocene. These predators leave a well preserved trace of predation in the form of a borehole in the shell of the prey. This study focuses on 18 species of Miocene and Pliocene Turritella from the southeastern United States. Over five thousand individual shells were examined and measured, collected from 13 localities from Maryland to southern Florida.

Predatory efficiency is determined by a number of factors: shell thickness at drillhole site, vertical location of drillhole, percent of shells that have multiple drillholes, and percent of shells that contain incomplete drillholes. Shell thickness at drillhole and location of drillhole are measured because predators would benefit by expending less energy drilling into the thinnest part of the shell that is nearest the visceral mass of the prey. Multiple complete boreholes represent at least one failure to obtain food. Incomplete boreholes represent a drilling attempt which has failed to produce food at the cost of metabolic energy.

While the intensity of Naticid and Muricid predation of Turritella increases (χ2, α<.01), predators become less efficient from the Miocene to the Pliocene. Decreased predatory efficiency is indicated by an increase in the number of shells with multiple and incomplete drilling sites (χ2, α<.01). Although predators appear to have little radial preference, they indicate strong vertical preference for centrally located drilling sites (t-test, α<.01). Predators appear to be drilling into thicker parts of Turritelline shells and thus expending more energy in drilling -however, this pattern is not statistically significant (χ2, α>.20).

We show that the efficiency of Naticid and Muricid predators decreased from the Miocene to Pliocene. Decreased efficiency of predators might result from newly evolved structural changes in prey shells, new prey escape responses or problems in predator recognition of live versus dead prey shells resulting from high densities of both living and dead individuals.

It remains to be seen whether predatory efficiency declines over longer time scales. In light of previous studies which have concentrated on evolution in the shell shape and ornamentation of prey in response to predators, a more promising and direct measure of the efficiency of predation may lie in the study of the frequency of multiple and incompletely drilled shells. By this method we might better judge the effectiveness of defense mechanisms and the evolutionary significance of predator-prey escalation.

Documentation of microevolutionary changes in morphologic character complexes through geologic time, especially across speciation events, is one of the most significant contributions that paleontologists can provide to evolutionary biology. Papers treating patterns of evolution have established criteria required for the study of microevolution, which include: wide geographic coverage, a sequence of closely spaced samples, well defined taxa and rigorous biometric testing of large samples. Many excellent empirical studies of microevolution have taken great steps to maximize temporal resolution and to improve numerical treatment of data. Factors of ecophenotypic and geographic variation, however, have been neglected in most microevolutionary studies.

Late Paleozoic cyclothems of the North American midcontinent, with their fine stratigraphic resolution and well documented paleoenvironments that can be correlated over large geographic distances, provide a unique opportunity to study patterns of microevolution and concomitant ecophenotypic and geographic variation. Bryozoans are well suited for studies that require large morphometric data sets, because of their relative abundance, complexity, and the fact that fragmentary material can provide tenable data. Due to their colonial nature, limits of phenotypic versus genotypic variation.

In order determine the effects of geographic variation among the rhabdomesid genus Streblotrypa (Cryptostomata, Bryozoa), specimens were collected from nine localities, all taken from the lowermost six inches of the Winzeler Shale (Virgilian) distributed along a 300 km transect from south-central Kansas to northeastern Kansas. Data were collected from five specimens per locality, all from nearly identical paleoenvironments, and of very nearly the same age. Cluster analysis and discriminant analysis demonstrate some differences among the groups, however, no morphologic trends are found to correspond to geographic distributions, nor can specimens be readily assigned to locality based on morphology.

A strong genetic control within colonies is apparent. Individual observations (composite OTU's) can be assigned to the specimen from which they were measured with a very high degree of confidence. Variation between environments at the same locality over the shortest possible time span (estimated in the magnitude of 104 years) is currently being tested by analyzing data collected from the next unit above, a limestone with interbedded shales. Data from three other localities of similar environment, but significantly different age (+3 Ma), are also being analyzed to further test the degree of morphologic variation with environment verses time.

Results obtained using standard multivariate techniques applied to morphometric data are building a composite picture of the characteristics of microevolutionary change within Streblotrypa.

The Bilk Creek Limestone of the Black Rock Terrane in northwestern Nevada and the McCloud Limestone of the Eastern Klamath Terrane in northern California contain a diverse and abundant Permian brachiopod fauna currently under study. The composite rock record of both limestones spans the Wolfcampian and Leonardian stages of the Permian, during which both terranes were part of a volcanic arc separated from the North American continent by a marginal basin of unknown dimension. Brachiopods of this volcanic arc provide important evidence bearing on current hypotheses of Permian paleobiogeography and paleogeography.

The Bilk Creek/ McCloud brachiopods are best characterized as an endemic fauna of a unique province and not as a mixed, “Tethyan” and North American fauna. The central problem of these arc faunas is not how similar they are to faunas of the Tethyan basin but why they are so dissimilar from North American faunas. Overlying rock units in both terranes contain Guadalupian brachiopod faunas that are North American in character. The paleobiogeographic pattern is one of decreasing levels of endemism throughout the Wolfcampian and Leonardian, to ultimate deprovincialization during the Guadalupian. This is not consistent with a pantropic dispersal hypothesis.

The temporal pattern is consistent with a paleogeographic hypothesis of initial, long-distance separation of arc and continent with convergence of the arc toward the North American continental margin. The dissimilarity of the arc brachiopod faunas to coeval, same-environment faunas of North America suggests that the marginal basin that separated the two must have been several thousand kilometers wide during the Early Permian, producing the endemic fauna. A Japan-style model, with arc and continent in close proximity is not supported.

The marked increase in predation pressure at the close of the Palaeozoic must have had a profound effect on the evolution of the bivalves (Vermeij, 1983). In particular the epifaunal bivalves were extremely vulnerable to attack by the major molluscivore groups; fish, asteroids, crustaceans and boring and wedging gastropods.

The range of techniques employed by these molluscivores ranges from crushing and prising to boring and the range of effective defensive measures is correspondingly broad. Different methods of attack require different and, perhaps conflicting, defensive strategies. The bivalves undergo a massive radiation at the beginning of the Mesozoic, a time coincident with the increase in predation pressure (with the important exception of the boring gastropods which evolved much later in the Cretaceous). Given the range of methods of attack and the myriad of possible prey responses it is possible to interpret almost any change in life habit or morphology happening at that time as defensive. Temporal coincidence is not sufficient and such interpretations should be supported with experimental data from predation on Recent malacofauna.

Nevertheless, a number of bivalve life habits may be interpreted as having evolved in response to predation pressure. Inevitably certain taxa are prevented from evolving particular defence mechanisms by the constraints of their body plans. The aim of this paper is to explore the different evolutionary pathways followed by different clades in terms of their constructional potentialities and constraints.