Seventeen species of decapod crustaceans have been described from Campanian through Paleocene rocks in the Santa Marta, López de Bertodano, and Sobral Formations of the James Ross Basin, Antarctica. Of these, nine are new species: Metanephrops rossensis, Glyphea australensis, Paguristes santamartaensis, Munidopsis foersteri, Retrorsichela laevis, Plagiophthalmous collinsi, Rhinopoupinia bicornis, Cristafrons praescientis, and Torynomma (Torynomma) australis. One new family, Retrorsichelidae, and three new genera, Retrorsichela, Rhinopoupinia, and Cristafrons, were also named. This assemblage includes the first notice of brachyurans from the Cretaceous of Antarctica; six species are described. The nephropid lobster Hoploparia stokesi (Weller), the most common decapod throughout the section, exhibits significant morphological change throughout its range from late Santonian or earliest Campanian to Paleocene; however, variation of key features is asynchronous. The raninid brachyuran, Cristafrons praescientis, is second in abundance to H. stokesi. The occurrence of Metanephrops rossensis and Munidopsis foersteri represents the oldest geological records for these genera and the recognition of species of Paguristes, Plagiophthalmous, Torynomma, and Necrocarcinus constitutes the first notice of these genera in Antarctica. Of those taxa that have living congenors, the species of Metanephrops, Linuparus, and Munidopsis occupied habitats at inner shelf depths in the Cretaceous whereas their extant descendants are restricted to outer shelf and bathyal depths. This diverse decapod fauna is dominated by genera that range into the Cenozoic and appears to be a pioneer assemblage.

Multielement taxonomy and shape analysis have led to substantial revisions in the taxonomic concepts of 13 Frasnian species of Palmatolepis, which previously have been based largely on visual discrimination of the Pa elements. Septimembrate apparatuses have been recognized in three species and diagnostic Pb elements are associated with the Pa elements of eight others. The multielement reconstructions thus derived provide the a priori classification that is tested by the canonical variate analysis of the outlines of the Pa elements. The outlines are digitized from a TV image and quantified by calculating mean tangent angles within a specified number of intervals between landmarks. The mean tangent angles for each interval are the variables used in the canonical variate analysis. In a series of comparisons limited to three species each, all 13 species separate into isolated clusters that are completely congruent with the a priori groups based, with two exceptions, on multielement taxonomy. Thus, shape analysis provides a rigorous separation of closely similar species that have been difficult to distinguish by visual discrimination of the Pa elements. Shape analysis is treated herein as an integral part of the systematic descriptions. Newly described species are P. bohemica, P. boogaardi, P. luscarensis, and P. muelleri. The new taxonomic concepts lead to significant revisions in the biostratigraphic ranges of a number of species of Palmatolepis involved in the zonation and graphic correlation of the Frasnian Stage.

Fourteen species of brachiopods were collected from two measured sections on Khios, and although the sections are only about 4 km apart, they contain but one genus in common. Both collections are from the zone of Neoschwagerina, but the collection from the hill called Seladha is probably somewhat younger than the collection from the region called Agrelias, because it is accompanied by the first appearance of the fusulinid Verbeekina. The brachiopods at Agrelias are: Kotlaia aethopa n. gen. and sp., Schuchertella tapina n. sp., Derbyia dirata n. sp., Meekella megala n. sp., Seseloidia phlebodes n. gen. and sp., Tschernyschewia sp. indet., Marginifera ganota n. sp., Entacanthadus chioticus n. gen. and sp., Horridonia sp. A., and Linoproductus cf. L. lineatus Waagen. The fauna at Seladha contains: Linoproductus cf. L. lineatus, Composita sp. indet., Squamularia sp. indet., Hustedia sp. indet., and Timorina sp. indet. Both faunas are dated as middle Permian, Kungurian, perhaps equivalent to the lower and upper parts of the Wordian of North America. The type species of Kotlaia is K. capillosa n. sp. from the Permian of the Salt Range, Pakistan, and a new genus of hercosiid (Sicularia) from the Permian of Sicily is introduced for nomenclatural reasons, with type species Richthofenia sicula Gemmellaro.

Specimens of the Late Mississippian productoid genera Inflatia and Keokukia from northeastern Oklahoma and northwestern Arkansas, collected from the Boone and “Moorefield” Formations, Hindsville Limestone, and Fayetteville Shale, display morphologic similarities and differences that delineate species and determine their biostratigraphic ranges. Generic assignments are based primarily on internal characters. Systematic descriptions include seven species of Inflatia Muir-Wood and Cooper: Productus inflatus McChesney (the type species), P. cherokeensis Drake, P. clydensis Girty (figured herein for the first time and for which a lectotype is designated), four new species of Inflatia (I. cooperi, I. gracilis, I. pusilla, and I.? succincta), and one species of Keokukia (the type species for the genus, K. sulcata Carter). Also proposed and described is a new genus, Adairia, with its type species Productus (Marginifera) adairensis Drake. All these species of Inflatia, Keokukia, and Adairia have biostratigraphically restricted ranges within the Meramecian and Chesterian sequence in the Ozark region.

Maastrichtian sediments exposed in the Bay of Biscay region at coastal sections at Zumaya and Sopelana, northern Spain, and Hendaye and Bidart, France, yield the most diverse Upper Maastrichtian ammonite faunas yet recovered. Thirty-two species/subspecies referred to 21 genera are described, one of which, Anapachydiscus terminus, is new. The ranges of all taxa are fully documented and provide the basis for a four-fold division of the uppermost Campanian and Maastrichtian, with zones of Pseudokossmaticeras tercense (oldest), Pachydiscus (P.) epiplectus, Anapachydiscus fresvillensis, and A. terminus (youngest). This represents the most refined, and first properly documented, ammonite zonation for the Maastrichtian of western Europe, and can be directly correlated with the belemnite zonation developed for the white chalks of northern Europe. The extinction of the last ammonites, documented here, occurred at relatively high standing diversity and appears to have been sudden and catastrophic.

Palynological analysis of the highly fossiliferous marine clays of the St. Erth Beds of Cornwall has revealed the presence of dinoflagellates, acritarchs and prasinophytes, scolecodonts, microforaminiferal linings, freshwater? invertebrates, freshwater algal spores, embryophyte spores and pollen, fungal spores, and plant cuticles. These groups are documented here and several, including the dinoflagellates, are reported from the St. Erth Beds for the first time.

The marine clays were deposited in warm, shallow waters of an inlet or embayment during a probable high stand in sea level. They are generally held to be of late Pliocene age, planktonic foraminiferal evidence placing them at between 1.9 and 2.1 Ma (late late Pliocene). Dinoflagellates are consistent with a late Pliocene age. Spores and pollen, if not reworked, suggest placement no higher than the lower part of the Tiglian Stage (upper Pliocene) of The Netherlands.

Analysis of all palynological groups permits terrestrial and marine climates to be evaluated independently. The spore-pollen assemblage has some thermophilic elements but mainly reflects a cool-temperate terrestrial climate. In contrast, dinoflagellates—dominated by gymnodinialean? and protoperidinioid cysts—indicate warm inner neritic waters and present some evidence for subtropical to tropical conditions with winter sea-surface temperatures above 15°. Increased influence of the Gulf Stream during the late Pliocene, perhaps superimposed upon a phase of global warming, is hypothesized to explain these differentially elevated marine temperatures.

The St. Erth inlet was not markedly brackish or hypersaline judging from the dinoflagellates, but rare freshwater algal spores attest either to some freshwater input or redeposition from sandy soils during marine incursion. High abundance of scolecodonts, about 1,500 to 2,000 per gram dry weight of sediment, allows speculation that the inlet hosted a thriving association of latest Pliocene marine annelid worms.

A species of algae incertae sedis, Halodinium scopaeum, and three species of dinoflagellate, Algidasphaeridium? euaxum, Sumatradinium pliocenicum, and Trinovantedinium sterthense, are proposed as new. The dinoflagellate genus Selenopemphix Benedek, 1972, is emended herein. Quinquecuspis Harland, 1977, is now validated by the transfer of Trinovantedinium concretum Reid, 1978, to Quinquecuspis Harland, 1977, as Q. concreta n. comb.

Cambrian–Ordovician boundary interval dendroid graptolites and conodonts occur in continental slope facies in the Taconic allochthon. The upper part of the Hatch Hill Formation has lowest Ordovician (lowest Tremadocian) nematophorous dendroid and lower Fauna B-aspect conodont assemblages with Cordylodus caseyi (emend.) and Iapetognathus preaengensis. Comparable dendroid-conodont faunas occur in Baltoscandia, northeastern China, and western Newfoundland; this suggests that no diachroneity can be demonstrated between the lowest occurrences of Rhabdinopora flabelliformis in a number of faunal provinces.

A practical and correlatable Cambrian–Ordovician boundary stratotype horizon defined by the lowest occurrence of a Rhabdinopora flabelliformis assemblage within an interval with lower Fauna B-aspect conodonts is advocated. A biostratigraphic horizon defined by conodonts has far less utility due to strong lithofacies-conodont biofacies linkages, unresolved problems with the species-level taxonomy of cordylodans, and possible diachronous first-appearances of Cordylodus species. Because the areally most extensive Cambrian–Ordovician boundary sequences are siliciclastic-dominated (Avalonian, Baltoscandian, Gondwanan-Hercynian platforms and shale-dominated slope sequences), the lowest local occurrence of R. flabelliformis assemblages provides a practical and traditional definition for the base of the Ordovician System and Tremadocian Series in regions where conodonts are rare or recoverable only with difficulty.

Strata correlative with the Cambrian–Tremadocian boundary interval are not represented across most of Laurentia. In this region, the “Sauk III Subsequence” locally has an important unconformity within it, and lower Tremadocian-equivalent rocks can unconformably overlie units as low as the Proterozoic. The earliest Ordovician featured a relatively simple eustatic history characterized by an “early Tremadocian onlap”; no compelling evidence supports a eustatic fall-rise couplet, or “Black Mountain eustatic event,” in this interval. Available stratigraphic information is reinterpreted to demonstrate an initially slow and subsequently higher rate of continued sea level rise in the Cambrian–Ordovician boundary interval.

The marine molluscan fauna of the Prince Creek Formation near Ocean Point, northern Alaska, is of Danian age. It is the only diverse and abundant Danian molluscan fauna known from the Arctic Ocean realm, and is the first evidence for an indigenous Paleocene shallow-water biota within a discrete Arctic Ocean Basin faunal province.

A high percentage of endemic species, and two endemic genera, emphasize the degree to which the Arctic Ocean was geographically isolated from the world ocean during the earliest Tertiary. Many of the well-preserved Ocean Point mollusks, however, also occur in Danian faunas of the North American Western Interior, the Canadian Arctic Islands, Svalbard, and northwestern Europe, and are the basis for relating this Arctic Ocean fauna to that of the Danian world ocean.

The Arctic Ocean was a Danian refugium for some genera that became extinct elsewhere during the Jurassic and Cretaceous. At the same time, this nearly landlocked ocean fostered the evolution of new taxa that later in the Paleogene migrated into the world ocean by way of the northeastern Atlantic. The first Cenozoic occurrences are reported for the bivalves Integricardium (Integricardium), Oxytoma (Hypoxytoma), Placunopsis, Tancredia (Tancredia), and Tellinimera, and the oldest Cenozoic records given for the bivalves Gari (Garum), Neilo, and Yoldia (Cnesterium). Among the 25 species in the molluscan fauna are four new gastropod species, Amauropsis fetteri, Ellipsoscapha sohli, Mathilda (Fimbriatella) amundseni, and Polinices (Euspira) repenningi, two new bivalve genera, Arcticlam and Mytilon, and 15 new bivalve species, Arcticlam nanseni, Corbula (Caryocorbula) betsyae, Crenella kannoi, Cyrtodaria katieae, Gari (Garum) brouwersae, Integricardium (Integricardium) keenae, Mytilon theresae, Neilo gryci, Nucula (Nucula) micheleae, Nuculana (Jupiteria) moriyai, Oxytoma (Hypoxytoma) hargrovei, Placunopsis rothi, Tancredia (Tancredia) slavichi, Tellinimera kauffmani, and Yoldia (Cnesterium) gladenkovi.

I want to begin by thanking you for giving me the opportunity to serve as President of The Paleontological Society and especially for the boundless cooperation I have received from you, the members. Few scientific societies work as well as The Paleontological Society. Some societies function because of the dedication of a few fully committed members. Others rely on paid, professional staff to conduct the society's business. In contrast, the success of The Paleontological Society stems from the day-to-day enthusiasm for our roles and goals that is distributed uniformly across the membership. Holding this office has been a high privilege, and I am grateful to you for having selected me.

The family Palaeothentidae contains some of the dentally more specialized of the small-bodied marsupials of South America and was a clade almost equivalent with the Abderitidae in having been the most abundant caenolestoids. They were unquestionably the most diverse, containing two subfamilies, nine genera, and 19 species, with a distribution ranging from Colombia to Tierra del Fuego. The best and most continuous record of the Palaeothentidae is from Patagonian Argentina where eight genera and 17 species are recognized. There, the Palaeothentidae ranged in age from the Deseadan (later Oligocene) through the late Santacrucian (middle Miocene—the Santacrucian record lasting from about 19.4 m.y. to considerably less than 16.05 m.y. before the present). The family appears to have survived longer in Colombia. The palaeothentine Palaeothentes boliviensis (Bolivia) and the incertae sedis genus and species Hondathentes cazador (Colombia) are the only taxa restricted to an extra-Argentine distribution.

Two palaeothentid subfamilies are recognized. The subfamily Acdestinae is new and is erected to accommodate four genera and five species of herbivorous to frugivorous palaeothentids known from the Deseadan through the middle–late Santacrucian. Three of those genera are new (Acdestoides, Acdestodon, and Trelewthentes), as are three acdestine species placed in the genera Acdestodon, Trelewthentes, and Acdestis. The largely faunivorous Palaeothentinae includes four genera and 13 species; the genera Propalaeothentes and Carlothentes are new and new species are described for the genera Propalaeothentes (2) and Palaeothentes (3). Carlothentes is named for Ameghino's Deseadan species Epanorthus chubutensis, and Ameghino's genus Pilchenia is resurrected to accommodate Deseadan P. lucina. New species include: Acdestodon bonapartei, Trelewthentes rothi, Acdestis lemairei, Palaeothentes marshalli, P. migueli, P. pascuali, and Propalaeothentes hatcheri.

The Palaeothentinae contains more generalized palaeothentid species than does the Acdestinae, but also includes some very specialized forms. The most generalized known palaeothentid is the Colombian Hondathentes cazador. Both the Acdestinae and Palaeothentinae have large- and small-bodied species; Palaeothentes aratae was the largest palaeothentid (about 550 g), and P. pascuali n. sp. the smallest (about 50 g). The oldest known members of both subfamilies consist of five of the six largest palaeothentids.

The evolutionary history of the Palaeothentidae is complicated by thick sequences containing no fossils, several lacunae in sequences that yield fossils, and a continent-wide distribution of localities. By far the densest and most continuous record of the family exists in the coastal Santa Cruz Formation of Patagonian Argentina. Three major clades exist within the Palaeothentidae: 1) the incertae sedis species Hondathentes cazador; 2) the Acdestinae; and 3) the Palaeothentinae (including the new genus Propalaeothentes). The evolution of dental characters in these clades is documented with the aid of 719 new specimens (about 80% of the hypodigm of the family), most of which (about 90% of the new specimens) have precise stratigraphic data.

Biostratigraphic study of the new samples was assisted by a new technique of temporal analysis of paleosols and by radiometric age determinations, the latter indicating that the upper part of the Pinturas Formation (16.6 Ma) is older than the lower part of the Santa Cruz Formation (16.4 Ma) and that the top of the marine Monte León Formation (Grupo Patagonica) is older than either (19.4 Ma).

Fifty-two gnathic and dental characters were used to identify the taxonomy and to reconstruct the phylogeny of the Palaeothentidae. Analysis of sequencing of appearances of derived characters documents rampant convergences at all taxonomic levels and considerable phenotypic plasticity (variable percent representation of different mutable character morphs) in the organization of the palaeothentid dentition. Certain highly generalized character states survive for the duration of the family in some lineages, whereas others are phenotypically lost for a time and then reappear as a minor percentage of character variability. In general, replacement faunas of palaeothentids were morphologically more generalized than their antecedent forms. The high rate of character mutability and the survival and reappearance of generalized dental characters in the Palaeothentidae were probably related to massive events of pyroclastic deposition that periodically caused at least local extinctions of small mammal populations throughout the duration of the Patagonian middle Tertiary. Dental character regression indicates that palaeothentids arose prior to the Deseadan from a relatively large-bodied marsupial having generalized tribosphenic molars with more or less bunodont cusps; probably an unknown member of the Didelphidae.

The type section of the Basal Silty Member of the Survey Peak Formation spans the Cambrian–Ordovician boundary (North American usage) at Mount Wilson in the southern Canadian Rocky Mountains. The zonal and subzonal terminology through the boundary interval developed in Texas and Oklahoma is applicable to the trilobite faunas recovered from the section. The oldest trilobites recovered in this study occur in the top of the underlying Mistaya Formation and are assigned to the Saukiella serotina Subzone of the Upper Cambrian Saukia Zone. Trilobites and brachiopods of the S. serotina and Eurekia apopsis Subzones of the Saukia Zone occur in the lower half of the Basal Silty Member; trilobites and brachiopods assigned to the Lower Ordovician Missisquoia Zone and the Symphysurina brevispicata Subzone of the Symphysurina Zone occur in the upper half of the Basal Silty Member. The S. brevispicata Subzone extends an unknown distance into the Putty Shale Member of the Survey Peak Formation.

The extinction horizons at the base of the Eurekia apopsis Subzone and at the base of the Missisquoia depressa Subzone (the Cambrian–Ordovician boundary) occur within the Basal Silty Member of the Survey Peak Formation, not at the formational contact with the underlying Mistaya Formation. This leaves hypotheses linking immigration of the replacement trilobite faunas to major lithofacies changes through the boundary interval as untenable. Critical review of the evidence for the extinctions at the end of the Ptychaspid Biomere suggests that they were caused by an invasion of the shelf region by cold, anoxic water.

Forty-seven taxa are illustrated and 18 of those which provide new taxonomic information are discussed. One new genus, Rampartaspis Loch, is described in addition to four new species: Eurekia plectocanthus Loch, Highgatella wilsoni Derby, Macronoda punctata Derby, and Rampartaspis dissimulosulcus Loch. The identifications of trilobites and brachiopods in this paper revise those of Aitken and Norford (1967) and Derby et al. (1972) and result in minor changes in the reported positions of the bases of the Missisquoia and Symphysurina Zones. Revision of the identification of some trilobites in Dean (1989) changes the biostratigraphic interpretation of the Basal Silty Member at Wilcox Pass, Albert, Canada.

Three species of the Paleozoic coral Palaeacis are described from northeastern Oklahoma and northwestern Arkansas. Included are the Chesterian species P. carinata Girty and P. snideri n. nom., a replacement name for the junior homonym P. cuneata Snider, and the Desmoinesian? species P. erecta n. sp. Coralla of each species exhibit two types of microstructure that characterize two skeletal zones. The outer skeletal zone is composed of numerous parallel trabeculae, mostly between 0.2 and 0.3 mm in diameter, that lie perpendicular to, and have their accretionary surfaces on, the exterior surface of the corallum. Trabeculae are closely spaced laterally and are not organized into rows except uncommonly on the distal portion of some coralla. Where trabeculae coalesce into parallel rows, ornamentation on the corallum exterior consists of parallel ridges or rows of small nodes. Where trabeculae are irregularly arranged, external ornamentation consists of irregularly disposed nodes. The inner skeletal zone consists of radially fibrous stereoplasm arranged into discrete septal spines that coalesce into irregularly developed septal ridges in each calice. In P. erecta, septal spines merge into continuous layers of fibro-normal stereoplasm in some places. On the basis of microstructure, corallum morphology, and external ornamentation P. carinata and P. snideri can be allied with P. axinoides Smyth and P. robusta Webb. Palaeacis erecta falls within the same group on the basis of microstructure and ornament, but has a unique corallum morphology.

Two distinct types of skeletal attachment occur in these Palaeacis species. Palaeacis carinata and P. snideri exhibit an encrusting attachment surface that results in a prostrate growth habit wherein smaller substrates were entirely engulfed, producing free-living coralla. Palaeacis erecta exhibits a small, circular attachment surface and an erect growth habit wherein most skeletal accretion occurs perpendicular to, and away from, the substrate. The substrate is not engulfed and the corallum remains attached and sessile throughout astogeny. Palaeacis erecta is, to date, the only Palaeacis species known to possess this erect, sessile growth form.

The calcareous heteractinid sponge Wewokella solida Girty, 1911, is reported from Colorado for the first time. Triactine-based skeletons are well preserved and dermal and gastral layers are composed of smaller spicules than those in the main wall of the many specimens. A fragment of an unnamed demosponge, possibly related to Heliospongia Girty, 1908, and fragments of root tufts occur with Wewokella in the Middle Pennsylvanian Minturn Formation near McCoy, in Eagle County, Colorado.

Outcrops of upper Miocene to upper Pliocene sediments in the Bocas del Toro Basin, Caribbean coast of western Panama, contain a record of the emergence of the southern Central American isthmus. Paleodepths and characteristics of past sedimentary regimes within the basin were determined from benthic foraminiferal species assemblages. The present Valiente Peninsula shallowed from upper bathyal depths of about 300–500 m to outer neritic depths of 150–200 m between latest Miocene (5.6–6.5 Ma) and middle Pliocene (3.5–3.6 Ma) times. Outer neritic assemblages from about 100–150 m paleodepth on the island of Escudo de Veraguas indicate negligible emergence through the late Pliocene, and their present sea-level altitude suggests rapid Quaternary shallowing. Middle neritic foraminiferal assemblages of Cayo Agua island shallowed from depths of about 40–80 m to 20–40 m between early (4.5–5.0 Ma) and middle (3.5–3.6 Ma) Pliocene times. Cayo Agua assemblages indicate establishment of a carbonate regime in the southwestern Caribbean region prior to complete closure of the Caribbean–East Pacific seaway around 3.5 Ma.

“Ladatheca” cylindrica (Grabau, 1900) was a eurytopic metazoan with a calcareous operculum and an elongate, gently tapering conch up to 15+ cm long and with an apical angle of approximately 0.75–2.0°. This apparent polychaete was geographically widespread in the sub-trilobitic Lower Cambrian of middle latitude, siliciclastic (middle and upper Placentian Series, Avalon Zone) and low latitude, carbonate platform (Tommotian Stage, Siberia(?) and Kazakhstan; and, probably, the upper Meishucunian Stage, southwestern China) sequences.

In situ conchs (vertically to steeply inclined, apex down) of “Ladatheca” cylindrica are common in deep subtidal, siliciclastic mudstones (Chapel Island Formation) and in a peritidal algal mud mound(?) limestone (West Centre Cove Formation) in southeastern Newfoundland. Closely juxtaposed conchs locally form a worm reef at the top of the West Centre Cove Formation. This structure is older than the oldest archaeocyathan build-ups and is the earliest known metazoan-constructed biostrome. “Ladatheca” cylindrica was a dominant element of the sessile benthos prior to its apparent ecological displacement by Coleoloides typicalis Walcott, 1889, in the upper Placentian Series.

Taxonomic keys are rarely used as an aid to the identification of foraminifera. Such keys become increasingly attractive, however, as the number of taxa which must be distinguished becomes large. The proliferation of known genera over the last 25 years is nowhere more apparent than in the unilocular calcareous foraminifera, where the number of genera has risen from 5 to 46. We present herein a dichotomous key in which any species may be assigned to its proper genus by progressing through a series of steps, consisting of paired statements, in which only one choice is made at a time.