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.

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.

An abundant, varied, and well-preserved assemblage of discrete sponge spicules of late Ordovician age is described from the Malongulli Formation of central New South Wales. It is associated with one of the most diverse Ordovician siliceous sponge faunas known. The assemblage occurs in allochthonous limestone blocks within breccia deposits of a predominantly graptolitic and spiculitic siltstone succession, and is composed mainly of hexactinellid spicule types. Included are a number of distinctive forms, recognized as new taxa—Silicunculus bengtsoni, Kometia cruciformis, Chelispongia prima, and Pseudolancicula exigua. All are new genera except Silicunculus Bengtson, 1986, which was previously described from the upper Cambrian of Queensland. The problematical Anomaloides reticulatus Ulrich, 1878, is reported for the first time from Australia. A wide variety of other diagnostic, but more generalized, spicule types also occurs, including stauractines, pinnular and nonpinnular pentactines and hexactines, ornamented oxyhexasters and echinhexasters, clavules, anchorate root-tufts, and uncinates. The pinnular pentactines may be assigned to the form genus Palaeorubus Ishiga (in Ishiga et al., 1987), interpreted incorrectly by Ishiga as a radiolarian. The sponges, discrete spicules, and radiolarians of these limestone clasts were transported in debris flows to a basinal setting from peri-platform oozes that formed on the flanks of the shallow offshore island-arc platform of the Molong High.

Lack of an adequately calibrated Devonian time scale precludes satisfactory comparisons of Recent and Devonian bryozoan diversities. Nevertheless, Devonian bryozoans apparently are 3–100 times less diverse than Recent bryozoans. This variation is a function of how Devonian time is divided (whole period, stages, per million years) as well as the diverse skeletal architecture of cheilostome bryozoans, the most abundant Recent bryozoan order.

The Givetian has the largest specific, generic, and familial diversity of any Devonian stage and the drop in bryozoan diversity from the Givetian to the Frasnian is greater than the rise or fall of diversity between any other adjacent stages. Diversity hardly changes among bryozoans across the Frasnian–Famennian boundary. Among bryozoans the Givetian–Frasnian extinction was a major event.

Devonian taxonomic diversity is less than nomenclatorial diversity, although both exhibit the same trends from stage to stage during the Devonian. The amount of difference between the two measures of diversity is probably a reflection of the intensity of research on Devonian Bryozoa, especially revisionary studies of previously described faunas. Monographic bursts in diversity are present and are a measure of the episodic character of taxonomic studies on less popular phyla. Examination of the literature commonly provides a finer stratigraphic resolution than indicated in compilations such as the Zoological Record.

Although some significant areas of the exposed continents have not received adequate study, Devonian bryozoans show marked geographic changes in diversity that can not be ascribed entirely to lack of study.

Gemmellaroia is a conical Permian brachiopod that traditionally has been assigned to the superfamily Richthofeniacea [sic] on the basis of its conical shape and a myocoelidium in the ventral valve. It has been considered unique among brachiopods in opening the shell by having the dorsal valve move straight up, rather than rotating around a hinge axis. Evidence is adduced to warrant transfer of the genus and its cohorts to the superfamily Derbyoidea (totally unrelated to the richthofenioids) and to demonstrate that it was capable of opening in the normal manner, rotating the dorsal valve about a hinge axis. Members of the family include Gemmellaroia (Cossmann, 1898), Loczyella Frech, 1901, Tectaria (Likharev, 1928), and Cyndalia (new genus with type species C. rudistiformis new species).

A nonmarine pelecypod occurrence was reported in 1977 within a zone of gray shaly mudstones yielding carbonized plants at Promontory Butte, Mogollon Rim, east-central Arizona. On paleobotanical evidence, the zone appeared then to be either of Late Carboniferous or Early Permian age. Work on 50 measurable shells indicates that the fauna is of Anthraconaia protracta Eagar and has wide variation. Standard dimensions of the Arizona fauna are identical to those of the type assemblage of A. protracta, which forms a thin band immediately above the Benwood Limestone of the Monongahela Group near Pittsburgh, Pennsylvania, 2,700 km to the east. The Arizona shell varieties match 50–60 percent of those from the band in Pennsylvania. Matching falls off rapidly to nil 70 m below this horizon and 100 m above it. Small differences in the trends of variation of the shells from Promontory Butte and Pennsylvania are accompanied by small differences in their respective host sediments, as reflected in their organic carbon and carbonate contents. When these results are compared with earlier conclusions on recurrent, apparently ecophenotypic, changes in the shape of Anthraconaia from other horizons in the Carboniferous and Lower Permian, they provide further evidence that the Arizona and Pennsylvania faunas were approximately contemporary. When the two bands are correlated, the Promontory Butte band is placed in the upper Pennsylvanian and in the upper Virgilian as traditionally accepted.

The middle Campanian Wolfe City Sand in northeastern Texas yields a distinctive ammonite and inoceramid fauna with Patagiosites sp., Placenticeras sp., Hoplitoplacenticeras (Hoplitoplacenticeras) minor n. sp., Baculites mclearni Landes, 1940, Trachyscaphites spiniger (Schlüter, 1872) porchi (Adkins, 1929), Inoceramus (Cordiceramus) azerbaidjanensis Aliev, 1939, and I. (Endocostea) balticus Boehm, 1907. The last-named four species allow a direct correlation with the Baculites mclearni zone of the Western Interior of the United States. The base of this zone has been dated at 79.9 ± 3.2/79.2 ± 1.6 Ma on the basis of K/Ar determinations on biotite from a bentonite. Inoceramus azerbaidjanensis is also known from the Campanian of the U.S.S.R. in Azerbaidjan (where the species was first described), western Turkemenia, Georgia, the northern Caucasus, the Crimea, and Donbass.

Ammonites are abundant in the phosphatic base of the Annona Chalk (Campanian) near Yancy in Hempstead County, Arkansas. The following are described: Pachydiscus (Pachydiscus) sp. (very rare), Placenticeras sp. (very rare), Nostoceras (Nostoceras) pulcher n. sp. (rare), N. (N.) monotuberculatum n. sp. (scarce), N. (N.) plerucostatum n. sp. (frequent), N. (N.) danei (frequent), Didymoceras sp. (rare), Didymoceratoides binodosum n. gen. and sp. (frequent), D. clardyi n. gen. and sp. (rare), Baculites taylorensis Adkins, 1929 (abundant), B. crickmayi Williams, 1930 (common), and Baculites sp. (abundant). The diverse Nostoceras association is typical of Gulf Coast upper Campanian rocks but Didymoceratoides is a Western Interior upper middle Campanian genus. Nostoceras (N.) monotuberculatum n. sp., however, is known from a single specimen from the basal upper Campanian Didymoceras stevensoni zone in Colorado.

The crustacean coprolite Favreina prima n. sp. and its internal structure are described from an upper Frasnian–lowermost Famennian limestone clast of moderately deep water origin, which derived from an Upper Carboniferous conglomerate of the Rif Mountains, northern Morocco. The fecal pellets were produced by early decapods that may be related to the Palaeopalaemonidae. Foraminifers of the stratigraphic marker genus Eonodosaria are associated with the coprolite. This is the third report of Paleozoic crustacean coprolites and the first occurrence prior to the Lower Permian.

Ophioxenikos langenheimi n. gen. and sp. (class Somasteroidea), Stibaraster ratcliffei n. gen. and sp., and Cnemidactis? macroadambulacralatus n. sp. (both class Asteroidea) are new stelleroid echinoderms described from Lower and Middle Ordovician strata of the western United States. Stibaraster clearly is at the asteroid grade of organization, although an early representative of the class. Ophioxenikos is the first fossil somasteroid recognized from beyond Europe. It is similar to Chinianaster and Villebrunaster, ambulacral characters of all three suggest affinities with ophiuroids. Cnemidactis? is recognized from North America; it is unusual in the presence of proportionately large marginal ossicles. An indeterminate species is unusual in its structural parallels with living taxa. In recent years, the possibility that edrioasteroids were ancestral to stelleroids has been revived. Supporting arguments for this hypothesis neglect important differences; ancestry of stelleroids remains uncertain.

At the well-known fossil mammal locality of Fort Ternan in southwestern Kenya, radiometrically dated at about 14 million years old (middle Miocene), fossil grasses have been preserved by nephelinitic sandstone in place of growth above a brown paleosol (type Onuria clay). Large portions of grass plants as well as fragments of leaves have revealed details of silica bodies, stomates, and other taxonomically important features under the scanning electron microscope. The computer database for grass identification compiled by Leslie Watson and colleagues was used to determine the most similar living grass genera to the five distinct kinds of fossil found. Two of the fossil species are assigned to Cleistochloa kabuyis sp. nov. and C. shipmanae sp. nov. This genus includes one species from low fertility dry woodland soils of New South Wales and Queensland and a second species from “raw clay soils” in western New Guinea. A third fossil species, represented by a large portion of a branching culm, is assigned to Stereochlaena miocenica sp. nov. This genus includes five species of low-fertility woodland soils in southeastern Africa. Both Cleistochloa and Stereochlaena are in the supertribe Panicanae of the subfamily Panicoideae. A fourth species is assigned to Distichlis africana sp. nov. and provides a biogeographic link between the single species of this genus now living in coastal grasslands in southeastern Australia and the 12 species of dunes and deserts found throughout the Americas from Patagonia and the West Indies to the United States and Canada. A fifth species is, like D. africana, in the subfamily Chloridoideae, but its stomata were not seen and it could belong to Cyclostachya, Pogoneura, or Polevansia. This earliest known wooded grassland flora in Africa is taxonomically unlike the modern grass flora of fertile volcanic African landscapes, and may have been recruited from an archaic grass flora of Gondwanan desert and lateritic soils.

Cuticular features and details of fine venation are now widely relied upon in systematic and phylogenetic studies of fossil plants. Where fossil leaves are robust or adherent to the matrix, such features may be readily available, but should the remains be fragile and subject to damage or loss, it may be necessary to preserve their integrity immediately following recovery and during transport. Clays, shales, and fossil leaf compressions are particularly vulnerable to the drying environment; fossil specimens are commonly damaged or entirely lost due to spalling, cracking, and shrinking of the clays or due to exfoliation of the organic film caused by differential drying. In an attempt to eliminate these problems, a technique using a mixture of nitrocellulose lacquer and acetone to coat fossil leaf compressions was developed for use on freshly excavated specimens under a wide range of climatic conditions (subfreezing to warm, dry or wet) while in the field. Many other preservational techniques exist, but they are typically complex, expensive, time consuming, destructive, or were developed for use in a laboratory setting.

Coccolithus crassus was described by Bramlette and Sullivan (1961) from the Lodo Formation of California. This species has a short stratigraphic range within the lower Eocene and its first occurrence is a marker for the CP10/CP11 zonal boundary in the widely used nannofossil zonation of Okada and Bukry (1980). Most nannofossil workers, however, do not report this index fossil, and the CP10/CP11 zonal boundary is often not determined. This is in contrast to the work of D. Bukry, who used the first occurrence of C. crassus for the CP10/CP11 boundary in virtually all lower Eocene DSDP cores that he examined (Figure 1). Apparently, there is considerable confusion about C. crassus. For instance, Romein (1979) considered C. crassus a junior synonym of Coccolithus eopelagicus (Bramlette and Riedel) Bramlette and Sullivan; Steinmetz and Stradner (1984, p. 741, Pl. 42, figs. 1 and 2) figured a specimen of Ericsonia subpertusa Hay and Mohler from Zone CP7 (upper Paleocene) as C. crassus; Perch-Nielsen (1985, p. 433, figs. 3.46 and 3.47, p. 504, figs. 58.12 and 58.13) mistook Toweius callosus Perch-Nielsen as C. crassus, as did Varol (1989, p. 302, Pl. 4, figs. 37 and 38). The main problem that prevents most workers from using this index fossil is that the species concept is largely unclear. It appears to be difficult to distinguish C. crassus from C. pelagicus or T. callosus based on the light micrographs of Bramlette and Sullivan (1961, Pl. 1, figs. 4a and 4c), and scanning electron microscope (SEM) photographs of this species have never been published except one specimen of the species was illustrated in Matter et al. (1974, p. 914, Pl. 4, fig. 8) under the name Ericsonia ovalis Black.

The association of sponges and encrusting, attached, or burrowing organisms has been commented upon relatively little. Finks (1960) and Gundrum (1979), for example, noted the association of articulate brachiopods, barnacle borings, bryozoans, gastropods, and rugose and tabulate corals with various upper Paleozoic sponges and, more specific to this paper, Morris and Whittington (1985) illustrated the inarticulate brachiopod Micromitra attached to the Cambrian sponge Pirania. During the summer of 1991, two scree-derived specimens of sponge-inarticulate brachiopod associations on two separate pieces of shale were collected from Abbott River (Figure 1), Cornwallis Island, Arctic Canada (75°14′N, 95°45′W).

Preservation of pristine pigmentation in fossil shells is a rare phenomenon (Teichert, 1964) and fossilization accompanied by recrystallization often renders the primary color bands indiscernible (Shrock and Twenhofel, 1953). Nevertheless, there are reports on color markings in fossil shells ranging from the Middle Cambrian to Holocene (Hoare, 1978; Mapes and Hoare, 1987; Kobluk and Mapes, 1989).

In 1892 the Swedish paleontologist Johan Christian Moberg described and illustrated what he interpreted as a fossil insect (Hemiptera) from beds of early Ordovician age in the southernmost limestone quarry at Killeröd, Smedstorp Parish in Skåne [Scania], southern Sweden. In a later paper in the same year (Moberg, 1892b), he also made a further passing reference to the presence of the same fossil when describing the accompanying graptolite fauna from Killeröd. One of his main reasons for recording this find was his conclusion (Moberg, 1892a, p. 122) that “it is evidently of great interest with full certainty to be able to prove the presence of airbreathing (terrestrial) animals as far back in time as that during which the oldest strata of the lower Silurian [i.e., Ordovician] were formed” [translation from Swedish].

Echinoid fragments were reported by Zachos (1990) from a Weches Formation (Clairborne) outcrop on Hooker Creek in Burleson County, Texas. Enough fragments have been found at the latter locality to piece together a composite identifiable as a species of the spatangid genus Maretia, most likely M. arguta. This species has not previously been reported outside of Clarke County, Mississippi. A search of the stratigraphic collections of the Texas Memorial Museum in Austin, Texas, has uncovered several previously unidentified specimens of M. arguta from two Weches localities, at Kickapoo Shoals on the Trinity River in Houston County and at Nacogdoches in Nacogdoches County. In addition, spatangoid fragments, some of which are attributable to M. arguta, are common in collections from the Weches and Cook Mountain Formations.

In 1990 (Fluegeman and Orr) the writers published a short study on known North American cyclocystoids. This enigmatic group is best represented in the United States Devonian by only two specimens, both illustrated in the 1990 report. Previously, the Cortland, New York, specimen initially described by Heaslip (1969) was housed at State University College at Cortland, New York, and the Logansport, Indiana, specimen was housed at Ball State University, Muncie, Indiana. Both institutions recognize the importance of permanently placing these rare specimens in a proper paleontologic repository with other cyclocystoids. Therefore, these two specimens have been transferred to the curated paleontologic collection at the University of Cincinnati Geological Museum where they can be readily studied by future workers in association with a good assemblage of Ordovician specimens of the Cyclocystoidea.

The impetus for writing this paper has come from many people who have shown an interest in the device we describe; prior to this paper, we had no reference to provide for interested parties. The original device was described in Elmgren (1973) and illustrated in Thomas (1986). These papers are not readily available to many micropaleontologists; hence, we felt the need to redescribe it here with a few modifications. Traditionally, foraminiferal researchers, especially those working in fossil deposits, work on samples that are first processed and then dried. To split these dry samples to aliquots of manageable numbers of foraminifera, they use the well-known “Otto” microsplitter, which provides accurate splits plus or minus 10–20 percent.

This technique is effective for completely breaking down moderately calcareous to noncalcareous mudstones and shales to produce a concentrated residue of microfossils and non-clay minerals. I have applied this treatment to Mississippian and Pennsylvanian age mudstones and have easily retrieved abundant conodonts, ostracodes, foraminifers, spores, wood fragments, fish teeth, vertebrate bone fragments, silt, mica, pyrite crystals and framboids, and phosphate nodules. All of the above items emerge from the treatment with fine structures such as spines and surface ornamentation undamaged and completely free of surficial clay. This technique is a modification of that of Lund (1970). The chemical used by Lund (Union Carbide Amine 220) is no longer manufactured and an effective alternative is reported here. Furthermore, the additional steps in processing reported here increase the efficacity of the technique for completely dissolving indurated mudstones.