Freeliving corals capable of automobility (e.g., lateral migration) were rare during Paleozoic time, but some species within the tabulate genera Procterodictyum, Procteria (Granulidictyum), P. (Pachyprocteria), Palaeacis and Smythina, and the rugose genera Combophyllum, and Baryphyllum, have morphologic characters that suggest they were capable of such self-directed movement. The rugose corals Gymnophyllum and Hadrophyllum, sensu stricto may have exhumed and righted themselves. No single morphological character is diagnostic for an automobile habit, but the following characters appear to be important indicators: 1) lack of an external attachment surface; 2) concentric skeletal accretion; 3) discoid corallum shape; 4) concavo-convex, plano-convex, and, less commonly, biconvex corallum profile; and 5) small, lightweight corallum. Additionally, the occurrence of corallites on the base of the corallum (hypocorallites) is a good indicator of automobility in freeliving corals, but the character is so far known only in Procterodictyum. All known fossil automobile taxa appear to have inhabited relatively quiet environments on muddy or silty, soft substrates.

The earliest known automobile corals were early Emsian (Devonian) Procterodictyum. Paleozoic automobile corals were most abundant during Devonian time, with Procterodictyum, Procteria (Granulidictyum), and Combophyllum distributed in a narrow longitudinal band in the southern hemisphere on both sides of the Rheic Ocean. Carboniferous and Permian automobile taxa (Palaeacis partim, Smythina and Baryphyllum) were less diverse, but more cosmopolitan. Throughout Paleozoic time, the vast majority of automobile corals was confined to within 40 degrees of the paleoequator. However, additional research will be required before coral automobility can be used to constrain paleolatitude independently.

The successful definition of chitinozoan genera depends primarily on the precision of the criteria used. A standardized morphological terminology based upon details from scanning electron microscope observations of the most representative taxa bearing these characters is therefore proposed. The 143 genera, or subgenera, described so far in the literature are reviewed in order to exclude invalid taxa and obvious junior synonyms. Particular attention is paid to preventing the overlap of generic definitions of the 56 genera ultimately retained. A brief account of the diagnostic features and stratigraphic range of selected genera is given, and basic information concerning the type material of these genera is listed. Finally, a suprageneric classification of the whole Chitinozoa group based on diagnostic features whose hierarchy is established on statistical and evolutionary grounds, is given. One new subfamily, Pogonochitininae, three new genera, Baltochitina, Hyalochitina, and Saharochitina, and a new species Baltochitina nolvaki, are defined. The subspecies Fungochitina fungiformis spinifera is elevated to a specific rank.

Neritic dinoflagellates from periplatform (slope) carbonates of the Clino borehole, located on the western, leeward margin of the Great Bahama Bank, record environmental fluctuations on the platform top. A lower Pliocene interval (3.6–4.2 Ma) contains platform-top sediments shed onto the lower slope when the platform was open and ramplike. Despite this open topography, abundant Polysphaeridium zoharyi indicate the presence of restricted marine environments on the platform top. Terrestrial palynomorphs are rare throughout this interval and imply a mostly or fully submergent platform top.

By late Pliocene times (about 2.1–2.3 Ma) the platform had become flat-topped and steep-sided, with the Clino site located on its upper slope. Samples characteristic of sea-level highstands and lowstands were selected for analysis. Polysphaeridium zoharyi is abundant only in lowstand samples and may have thrived in proximity to terrestrial vegetation. In highstand samples Lingulodinium machaerophorum replaces P. zoharyi, perhaps in response to less restricted marine environments on the platform top. This change in assemblages, along with apparent variations in cyst influx, reflects a fluctuating history of currents and salinities over the platform top in the late Pliocene. Upper Pliocene lowstand samples contain anomalously high proportions of terrestrial palynomorphs, allowing the identification of two phases of emergence and vegetation of the platform top. Palynology therefore appears to be a sensitive indicator of short-term (4th-order) sea-level change on carbonate platforms.

Dinoflagellate concentrations correlate positively with carbonate compaction, and infer that compacted layers have undergone dissolution of their metastable constituents. Dinoflagellate concentrations therefore can be useful in the often difficult task of assessing compaction and dissolution in fine-grained limestones where other indicators are absent.

The following dinoflagellate species are formally proposed: Operculodinium bahamense Head new species, Operculodinium? megagranum Head new species, and Spiniferites rhizophorus Head new species.

The peridiniacean dinoflagellate cyst Manumiella seymourensis new species described herein characterizes Maastrichtian shallow marine sediments cropping out on Seymour Island, northeastern Antarctic Peninsula. It dominates palynological assemblages throughout the lower Maastrichtian (and possibly uppermost Campanian) to lower upper Maastrichtian part of the López de Bertodano Formation. Despite its superficial similarity to some other southern mid to high paleolatitude Campanian-Maastrichtian species, M. seymourensis represents a discrete, biostratigraphically useful population of peridiniacean cysts. Its morphology and size parameters remain consistent throughout almost all of its stratigraphic range, equated with relatively stable environmental conditions throughout much of the Maastrichtian in the James Ross Basin. Morphological variations, equated with environmental change, are apparent in specimens in the lowermost and uppermost parts of its range.

The first major international trilobite conference (which also dealt with related arthropod groups) was convened by David Bruton in Oslo in 1973. That meeting resulted in a 467 page proceedings volume (Martinsson, 1975) that has become an indispensible reference on arthropod paleobiology. With its abundance of high-quality empirical work and influential ideas, the ongoing utility of “Fossils and Strata 4” is assured, yet it is also a fascinating microcosm of the themes and concerns of paleontology as a whole a quarter of a century ago. Paleoecology blossomed in the late 1960s and early 1970s. Autecology, and particularly functional morphology, dominates the volume, accounting for about one-third of the contributions. Plate tectonics was a relatively recent development in 1973 and, following the lead of Whittington and Hughes (1972), several papers tackled trilobite paleobiogeography. They vary from a bold attempt to determine oceanic circulation through the Ordovician by Ross to more conventional studies of biogeographic distribution that were aimed at providing further support for concepts of continental drift. There was a burgeoning interest in community paleoecology, and Richard Fortey's (1975) now-classic paper on the Early Ordovician faunas of Spitsbergen was the first to define trilobite “communities.” The volume was rounded out by diverse papers on trilobite anatomy based on material from the Burgess Shale and Beecher's Trilobite Bed, the microstructure of the trilobite cuticle, trilobites eyes, high level classification of trilobites, and various evolutionary themes (character displacement in agnostoids; adaptive radiation in Cambrian trilobites).

A well-preserved and moderately diverse acritarch assemblage was recovered from the upper Ordovician Maquoketa Shale of northeastern Missouri. Based on graptolite and conodont evidence, the Maquoketa in northeastern Missouri is considered Richmondian (=Ashgill) in age.

The acritarch assemblage comprises 28 species, distributed among 17 genera including two new genera, Caelatosphaera and Stictosoma. There are 11 new species, Baltisphaeridium adiastaltum, Caelatosphaera verminosa (type species), Dorsennidium undosum, Elektoriskos aktinotos, Lophosphaeridium acinatum, L. varum, Micrhystridium hirticulum, M. prolixum, Peteinosphaeridium accinctulum, P. septuosum, and Stictosoma gemmata (type species); together with two species similar to previously named species and three species left in open nomenclature. Cosmopolitan and stratigraphically important species identified include Baltisphaeridium perclarum Loeblich and Tappan, 1978; Cheleutochroa sp. cf. C. diaphorosa Turner, 1984; Dorsennidium hamii (Loeblich, 1970) Sarjeant and Stancliffe, 1994; Excultibrachium concinnum Loeblich and Tappan, 1978; Orthosphaeridium insculptum Loeblich, 1970; O. rectangulare (Eisenack, 1963) Eisenack, 1968, and Villosacapsula setosapellicula (Loeblich, 1970) Loeblich and Tappan, 1976. Polygonium gracile Vavrdová, 1966 emend. Sarjeant and Stancliffe, 1994 and Micrhystridium hirticulum new species dominate the assemblage, followed by Dorsennidium undosum new species, Baltisphaeridium oligopsakium Loeblich and Tappan, 1978, Veryhachium sp. cf. V. oklahomense Loeblich, 1970, Peteinosphaeridium accinctulum new species, and Lophosphaeridium acinatum new species. Additionally, the palynoflora contains chitinozoans, scolecodonts, cryptospores, and the enigmatic palynomorph Gloeocapsomorpha prisca Zalessky, 1917 emend. Foster, Reed, and Wicander, 1989.

Paleontologic-palynologic and sedimentologic evidence indicates that the Maquoketa Shale at the two studied localities accumulated under low energy, somewhat offshore, and unrestricted marine conditions. The present Maquoketa Shale acritarch palynoflora shows greatest similarity to those of the Sylvan Shale (Ashgill; Richmondian) of Oklahoma and the Maquoketa Shale (Caradoc and Ashgill) of Kansas. Whereas there are some cosmopolitan acritarch species present in the Maquoketa Shale, its palynoflora shows no pronounced similarity with age-equivalent acritarch suites from outside of North America.

Sponges have an unrealized potential importance in biogeographic analysis. Biogeographic patterns determined from our analysis of all published data on distribution of Ordovician genera indicate Early Ordovician sponge faunas have relatively low diversity and are completely dominated by demosponges. Early Ordovician (Ibexian) faunas are characterized by the widespread co-occurrence of Archaeoscyphia and the problematic Calathium. This association is commonly found in biohermal structures. Middle Ordovician faunas show an increase in diversity, and two broad associations are differentiated: Appalachian faunas (including Southern China and the Argentine Precordillera) and Great Basin faunas.

Late Ordovician faunas show important changes in diversity and provincialism. Hexactinellid and calcareous sponges became important and new demosponge families appeared. Four Mohawkian-Cincinnatian associations are recognized here, including: 1) Midcontinent faunas; 2) Baltic faunas; 3) New South Wales faunas; and 4) Western North American (California and Alaska) faunas. However, two separate biogeographic associations are differentiated based on faunal differences. These are a Pacific association (western North American and New South Wales) and an Atlantic association (Midcontinent Laurentia and Baltica).

Distribution of sponge genera and migration patterns are utilized to consider paleogeographic dispositions of the different continental plates, climatic features, and oceanic currents. Such an analysis points to close paleogeographic affinities between the Argentine Precordillera and Laurentian Appalachian faunas. However, significant endemicity and the occurrence of extra-Laurentian genera suggest a relative isolation of the Precordillera terrane during the Late Ibexian-Whiterockian. The study also shows a faunal migration from the Appalachian region to South China during the Middle Ordovician and the migration of faunas from Baltica to Laurentia in the Late Ordovician. The occurrence of Laurentian migrants in New South Wales during the Late Ordovician could be related to inferred oceanic current circulation between these two areas, although other paleogeographic features may be involved.

A modest assemblage of hexactinellid and calcareous sponges from the Pennsylvanian (Moscovian) Dikanre Formation has been recovered from the Uygur Autonomous Region in eastern Xinjiang Province in northwestern China. Hexactinellids include the reticulosid Stereodictyum proteron Rigby and Washburn, 1972, and the new amphidiscosid species Stioderma sinensis, S. micra, and S. mega. This is the first time the genera Stereodictyum and Stioderma have been reported from Asia. Also included in the assemblage is a silicified porate permosphinctan, Amblysiphonella cf. barroisi Steinmann, 1882, which is the first report of that genus from northwestern China. Species of Stioderma are described from nearly complete specimens for the first time. Previously described species have been based on isolated spicules or relatively small fragments.

Taxonomy of heliolitine corals, and tabulate corals in general, benefits from analysis of larger assemblages of coralla that approximate populations. Quantitative data derived from such assemblages allow intraspecific variation to be tested rigorously and illustrated, and similar, co-occurring species to be discriminated using normal patterns of continuous population variation. Field collection and analysis necessarily involve recording and comparing assemblages from the full spectrum of sedimentary facies available at any one stratigraphic level and from the maximum available stratigraphic range. The large published taxonomic literature on heliolitine corals is a daunting obstacle to identification at the species level because a substantial part appears to involve taxonomic splitting to a degree inconsistent with variation known in modern coral species. The heliolitine corals studied occur in Ludlow-age ramp and shelf carbonate facies in the Boothia Uplift region in the southern Arctic archipelago of Canada. The “population” approach resulted in discrimination of 18 morphotaxonomic species, belonging to five genera and four families. A few select morphologic characters, incorporated in simple identification keys, are particularly helpful in distinguishing the 11 heliolitid and four stelliporellid species present, and are useful in screening the voluminous literature on species of Heliolites. Six of the species compare closely to Silurian species reported from central Kazakhstan, West Siberia, and North China; few are shared with other regions. The principal affinities are consistent with occurrence in the Uralian-Cordilleran paleogeographic region in the Silurian northern hemisphere. Eight species do not appear to be recorded in published literature elsewhere and are apparently endemic.

A new enigmatic Lower Cambrian fossil, Spygoria zappania, is described From the Nevadella zone (Botoman) of Lander County, central Nevada. In gross morphology, Spygoria fossils consist of stacks of small (5–10 mm in diameter) irregular calcified cups that are preserved in vertical, concave-up life orientation. Stacks are linked laterally into large monospecific bioherms which flourished in a shallow turbulent marine environment.

The Spygoria organism is interpreted as a metazoan which presumably inhabited the uppermost cup in each stack and periodically secreted new cups as it grew upward. Absence of holdfast structures suggest that the organism was held in place by sticky mud until opportunistically cementing to adjacent individuals. The affinity of Spygoria remains problematical, though we suggest that its stacked structure somewhat resembles the cone-in-cone structure of Cloudina, which formed similar dense thickets in shallow turbulent carbonate environments during the terminal Proterozoic.

Three microfossil assemblages occur in the Mesoproterozoic Bangemall Group (1625-1000 Ma) of northwestern Australia, each occupying a different environmental and taphonomic setting. In peritidal environments, benthic prokaryotic filaments and spheroids of matting habit and small size were permineralized by early diagenetic silicification of stromatolitic carbonates. In shallow subtidal environments, benthic filaments of large size and nonmatting habit and planktonic sphaeromorph acritarchs with thin walls and moderate dimensions were compressed in mildly kerogenous shale. In deeper subtidal environments, planktonic megasphaeromorph acritarchs with thick walls were initially entombed in concretionary nodules in highly kerogenous shale and then permineralized by silica during later diagenesis. Taxonomic diversity and numerical abundance evidently decrease offshore. The three assemblages have typical Mesoproterozoic aspects: peritidal benthic habitats were dominated by Siphonophycus-Sphaerophycus-Eosynechococcus-Myxococcoides-Palaeopleurocapsa, shallow subtidal settings were occupied by Siphonophycus-Leiosphaeridia-Pterospermopsimorpha-Satka, and offshore plankton consisted solely of very large chuarid acritarchs. Because of its taphonomic restriction to mid-intertidal stromatolites, the peritidal assemblage can be equated in microenvironment with a similar assemblage in the Neoproterozoic Draken Conglomerate, suggesting that ecological stasis at the community level can last for intervals up to 900 million years. In the deeper subtidal assemblage, the common chuarid has an unusual mode of preservation, in three dimensions in early diagenetic concretions, revealing that it possesses a thick multilamellate wall. Because of this distinctive ultrastructure, the new genus Crassicorium is erected for these fossils, which are among the oldest indubitable eukaryotes. Very large (34-55 μm in diameter) filaments from shallow subtidal habitats are assigned to the emended species Siphonophycus punctatum.

Based on range data and generic composition, four stages of evolution are recognized for late Paleozoic trilobites of the contiguous United States. Stage 1 occurs in the Lower Mississippian (Kinderhookian-Osagean) and is characterized by a generically diverse association of short-ranging, stenotopic species that are strongly provincial. Stage 2 species are present in the Upper Mississippian and consist of a single, eurytopic, pandemic genus, Paladin. Species of Stage 2 are much longer-ranging than those of Stage 1, and some species may have persisted for as long as 12 m.y. Stage 3 is present within Pennsylvanian and Lower Permian strata and consists initially of the eurytopic, endemic genera Sevillia and Ameura as well as the pandemic genus Ditomopyge. During the middle Pennsylvanian the very long-ranging species Ameura missouriensis and Ditomopyge scitula survived for more than 20 m.y. During the late Pennsylvanian and early Permian, a number of pandemic genera appear to have immigrated into what is now North America. Stage 4 is restricted to the Upper Permian (late Leonardian-Guadalupian) strata and is characterized by short-ranging, stenotopic, provincial genera.

The main causal factor controlling the four-stage evolution of late Paleozoic trilobites of the United States is interpreted to be eustacy. Whereas Stage 1 represents an adaptive radiation developed during the Lower Mississippian inundation of North America by the Kaskaskia Sequence, Stage 2 is present in strata deposited during the regression of the Kaskaskia sea. Stage 3 was formed during the transgression and stillstand of the Absaroka Sequence and, although initially endemic, Stage 3 faunas are strongly pandemic in the end when oceanic circulation patterns were at a maximum. A mid-Leonardian sea-level drop caused the extinction of Stage 3 fauna. Sea-level rise near the end of the Leonardian and into the Guadalupian created an adaptive radiation of stentopic species of Stage 4 that quickly became extinct with the latest Permian regression.

Since the publication of Darwin (1859), the biological meaning of the Cambrian radiation has been debated. Most commentators agree, however, that the Cambrian radiation is fundamentally a time of major metazoan cladogenesis. In and of itself this does not necessarily mean that unique evolutionary processes operated during the Cambrian radiation. Phylogenetic analysis has been used to study the tempo of speciation during the radiation, and thus far there is no need to invoke special rules relating to the tempo of evolution. Instead, what seems unique about the Cambrian radiation is its place as an important episode in the history of life—that is, as the first major radiation of the Metazoa. Although the tempo of evolution during the Cambrian radiation may not have been uniquely high, there were largely unique tectonic events that transpired during the late Neoproterozoic and Early Cambrian, such as extensive cratonic fragmentation. Biogeographic analysis of Early Cambrian olenelloid trilobites reveals that these tectonic events powerfully influenced evolutionary and distributional patterns in this diverse and abundant trilobite group. This emphasizes the importance of physical earth history in generating evolutionary patterns. In the general study of macroevolutionary patterns and processes, earth history phenomena emerge as powerful forces influencing the history of life and provide insights into evolution that can best be inferred by paleontological data.

The current classification of scleractinian corals based upon gross morphological features has been found unsatisfactory due to additional information from skeletal microarchitecture and microstructure. It is necessary to investigate microstructural details and limits in morphologic variation within and between different coral clades before a revised classification is constructed. Variations in morphologic characters and microstructural details from a population of Dimorpharaea de Fromentel, 1861 (Family Microsolenidae) from Upper Bathonian (Jumara Dome) strata in Kachchh are described. The data used include the diameter (D) and height (H) of the corallum, number of corallites in the colony (NC), number of septa in the mother corallite at the center of the colony (NS), minimum distance between centers of central corallite and corallite of the inner ring (C1), minimum distance between corallite centers of the outer ring (C2), septal density (DS) and trabecular density (DT). The principal components analysis reveals that most of the variation is explained by “size” related characters (D and H) while corallite density (NC and C1) and septal structures (DS and DT) contribute to the second and third principal component axes, respectively. The microarchitecture and distribution of characters observed in the Kachchh Dimorpharaea require a re-evaluation of familial-specific concepts and suggest that the population belongs to a single species, Dimorpharaea stellans Gregory, 1900, rather than four nominal species (D. stellans, D. distincta, D. continua and D. orbica) as has been assumed.

The ‘granular’ wall microstructure of the Ordovician stenolaemate bryozoan Dianulites Eichwald, 1829, has been studied using ultrathin sections, scanning electron microscopy (SEM), analytical SEM, and cathodoluminescence. The timing of recrystallization and the presence of microdolomite inclusions in the skeletal walls implies that the original skeleton consisted of high-magnesium calcite (HMC). Although found in some modern cheilostomes, HMC has not been recorded in living stenolaemate bryozoans, but appears to have also been present in Nicholsonella and a few other Ordovician genera traditionally assigned to the trepostomes or cystoporates. The Russian type species of Dianulites, D. fastigiatus Eichwald, 1829, is revised and recorded for the first time in North America from the Fillmore Formation (Lower Ordovician) of Utah. Unusually among bryozoans, D. fastigiatus has turbinate, cone- or horn-shaped colonies, straight to slightly curved, with zooids opening on the flat, broad end of the cone; the sides of the cone comprise calcified exterior walls. This growth-form resembles some solitary rugose corals and other benthic animals thought to have lived with all but their tops buried in soft sediment. Such an interpretation is supported in Dianulites by the scarcity of epibionts on the exterior walls of the cone and by the occurrence of specimens comprising stacks of subcolonies, suggesting periods of partial burial of the living tissues by sediment.

Moderately well-preserved Middle Triassic radiolarians were recovered from bedded limestone exposed at about 3 km west of Kefamenanu, West Timor, Indonesia. This limestone probably from the Aitutu Formation is considered to be an allochthonous block and is embedded in the Neogene Bobonaro Complex. The radiolarian fauna in this limestone is characterized by abundant radiolarians of typical Tethyan forms and is identical to that of the early Fassanian (early Ladinian) of European Tethys and other related faunas reported from the Philippines, Russian Far East, and Japan. The Aitutu Formation is thought to be deposited in an ocean environment dominated by a warm-water current system originating from the low latitude Tethyan realm. Fifty-nine species belonging to 34 genera, including five unidentified genera, are systematically treated, among them, five new species; Parentactinia suparkai, Pseudostylosphaera timorensis, Cryptostephanidium? megaspinosum, Tetrarchiplagia compacta, and Planospinocyrtis kefaensis.

Eospongilla morrisonensis n. gen. and sp., the oldest-described freshwater sponge (Demospongea: Spongillidae), is found in the Upper Jurassic (?Oxfordian/Kimmeridgian to Tithonian) Morrison Formation, east-central Colorado, U.S.A. Eospongilla morrisonensis occurs within the well-developed lacustrine carbonate succession of the Morrison Formation, and is represented by two micritic body fossils with calcite-replaced megascleres that range in length from 180 to 300 μm and in diameter from 20 to 35 μm. Megascleres are simple oxeas and strongyles and lack apparent ornamentation, possibly due to the diagenetic replacement. The oxeas are straight but the strongyles display a slight curvature. Microscleres are absent; gemmoscleres were not observed.